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The evaluation of infections in transplant recipients involves consideration of both the donor and the recipient of the transplanted organ. Infections after transplantation are complicated by the use of drugs that are necessary to enhance the likelihood of survival of the transplanted organ, but that also cause the host to be immunocompromised. Thus what might have been a latent or asymptomatic infection in an immunocompetent donor or in the recipient before therapy can become a life-threatening problem when the recipient becomes immunosuppressed.


PRETRANSPLANTATION EVALUATION

A variety of organisms have been transmitted by organ transplantation (Table 12-1). Careful attention to the sterility of the medium used to process the organ combined with meticulous microbiologic evaluation reduces rates of transmission of bacteria that may be present or grow in the organ culture medium. From 2% to >20% of donor kidneys are estimated to be contaminated with bacteria—in most cases, with the organisms that colonize the skin or grow in the tissue culture medium used to bathe the donor kidney while it awaits implantation. The reported rate of bacterial contamination of transplanted stem cells (bone marrow, peripheral blood, cord blood) is as high as 17% but is most commonly ∼1%. The use of enrichment columns and monoclonal-antibody depletion procedures results in a higher incidence of contamination. In one series of patients receiving contaminated products, 14% had fever or bacteremia, but none died.


Results of cultures performed at the time of cryopreservation and at the time of thawing were helpful in guiding therapy for the recipient. In many transplantation centers, transmission of infections that may be latent or clinically inapparent in the donor organ has resulted in the development of specific donor-screening protocols. In addition to ordering serologic studies focused on viruses such as herpes-group viruses [herpes simplex virus types 1 and 2 (HSV-1, HSV-2), varicella-zoster virus (VZV), cytomegalovirus (CMV), human herpesvirus (HHV) type 6, Epstein-Barr virus (EBV), and Kaposi’s sarcoma–associated herpesvirus (KSHV)] as well as hepatitis B and C viruses, human immunodeficiency virus (HIV), human T-cell lymphotropic virus type I, and West Nile virus, donors should be screened for parasites such as Toxoplasma gondii and Trypanosoma cruzi (the latter particularly in Latin America). Clinicians caring for prospective organ donors should also consider assessing stool for parasites, should examine chest radiographs for evidence of granulomatous disease, and should perform purified protein derivative (PPD) skin testing or obtain blood for immune cell–based assays that detect active or latent Mycobacterium tuberculosis infection. An investigation of the donor’s dietary habits (e.g., consumption of raw meat or fish or of unpasteurized dairy products), occupations or avocations (e.g., gardening or spelunking), and travel history (e.g., travel to areas with endemic fungi) is also mandatory. It is expected that the recipient will have been likewise assessed. Because of immune dysfunction resulting from chemotherapy or underlying chronic disease, however, direct testing of the recipient may prove less reliable. This chapter considers aspects of infection unique to various transplantation settings.


INFECTIONS IN HEMATOPOIETIC STEM-CELL TRANSPLANT (HSCT) RECIPIENTS

Transplantation of hematopoietic stem cells from bone marrow or from peripheral or cord blood for cancer, immunodeficiency, or autoimmune disease results in a transient state of complete immunologic incompetence. Immediately after transplantation, both phagocytes and adaptive immune cells (T and B cells) are absent, and the host is extremely susceptible to infection. The reconstitution that follows transplantation has been likened to maturation of the immune system in neonates.The analogy does not entirely predict infections seen in HSCT recipients, however, because the new cells mature in an old host who has several latent infections already.Nevertheless, most infections occur in a predictable time frame after transplantation (Table 12-2).


BACTERIAL INFECTIONS

In the first month after hematopoietic stem-cell transplantation, infectious complications are similar to those in granulocytopenic patients receiving chemotherapy for acute leukemia (Chap. 11). Because of the anticipated 1- to 3-week duration of neutropenia and the high rate of bacterial infection in this population, many centers give prophylactic antibiotics to patients upon initiation of myeloablative therapy. Quinolones decrease the incidence of gram-negative bacteremia among these patients. Bacterial infections are common in the first few days after hematopoietic stem-cell transplantation. The organisms involved are predominantly those found on the skin or in IV catheters (Staphylococcus aureus, coagulase-negative staphylococci) and aerobic bacteria that colonize the bowel (Escherichia coli, Klebsiella, Pseudomonas). Beyond the first few days of neutropenia, infections with filamentous bacteria such as Nocardia become more common. Episodes of bacteremia due to encapsulated organisms mark the late posttransplantation period (>6 months after hematopoietic stem-cell reconstitution). Chemotherapy and use of broad-spectrum antibiotics place HSCT patients at risk for diarrhea and colitis caused by Clostridium difficile overgrowth and toxin production.


FUNGAL INFECTIONS

Beyond the first week after transplantation, fungal infections become increasingly common, particularly among patients who have received broad-spectrum antibiotics. As in most granulocytopenic patients, Candida infections are most commonly seen in this setting.With increased use of prophylactic fluconazole, infections with resistant fungi—in particular, Aspergillus and other molds (Fusarium, Scedosporium, Penicillium)—have become more common, prompting some centers to replace fluconazole with agents such as caspofungin, voriconazole, and posaconazole. The role of antifungal prophylaxis with these different agents, in contrast to empirical treatment for suspected or documented infection, remains controversial (Chap. 11). In patients with graft-versus-host disease (GVHD) who require prolonged or indefinite courses of glucocorticoids and other immunosuppressive agents [e.g., cyclosporine, FK506 (tacrolimus),mycophenolate, rapamycin (sirolimus), antithymocyte globulin, or anti-CD52 antibody (alemtuzumab, an antilymphocyte and antimonocyte monoclonal antibody)], there is a high risk of fungal infection (usually with Candida or Aspergillus), even after engraftment and resolution of neutropenia. These patients are also at high risk for reactivation of latent fungal infection (histoplasmosis, coccidioidomycosis, blastomycosis) in areas where endemic fungi reside and if they have been involved in activities such as gardening or caving. Prolonged use of central venous catheters for parenteral nutrition (lipids) increases the risk of fungemia with Malassezia. Some centers administer prophylactic antifungal agents to these patients. Because of the high and prolonged risk of Pneumocystis jiroveci pneumonia (especially among patients being treated for hematologic malignancies), most patients receive maintenance prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX) starting 1 month after engraftment and continuing for at least 1 year.


PARASITIC INFECTIONS

The regimen just described for the fungal pathogen Pneumocystis may also protect patients seropositive for the parasite T. gondii, which may cause pneumonia or, more commonly, central nervous system (CNS) lesions. The advantages of maintaining HSCT recipients on daily TMP-SMX for 1 year after transplantation include some protection against Listeria monocytogenes and nocardial disease as well as late infections with Streptococcus pneumoniae and Haemophilus influenzae, which are a consequence of the inability of the immature immune system to respond to polysaccharide antigens.


VIRAL INFECTIONS

HSCT recipients are susceptible to infection with a variety of viruses, including primary and reactivation syndromes caused by most HHVs (Table 12-3) and acute infections caused by viruses that circulate in the community. Herpes Simplex Virus Within the first 2 weeks after transplantation, most patients who are seropositive for HSV-1 excrete the virus from the oropharynx. The ability to isolate HSV declines with time. Administration of prophylactic acyclovir (or valacyclovir) to seropositive HSCT recipients has been shown to reduce mucositis and prevent HSV pneumonia (a rare condition reported almost exclusively in allogeneic HSCT recipients). Both esophagitis (usually due to HSV-1) and anogenital disease (commonly induced by HSV-2) may be prevented with acyclovir prophylaxis. For further discussion, see Chap. 80. Varicella-Zoster Virus Reactivation of herpes zoster may occur within the first month, but more commonly occurs several months after transplantation. Reactivation rates are ∼40% for allogeneic recipients and 25% for autologous recipients. Localized zoster can spread rapidly in an immunosuppressed patient. Fortunately, disseminated disease can usually be controlled with high doses of acyclovir. Because of frequent dissemination among patients with skin lesions, acyclovir is given prophylactically in some centers to prevent severe disease. Low doses of acyclovir (400 mg orally, three times daily) appear to be effective in preventing reactivation of VZV. However, acyclovir can also suppress the development of VZV-specific immunity.


Thus its administration for only 6 months after transplantation does not prevent zoster from occurring when treatment is stopped. Some data suggest that administration of low doses of acyclovir for an entire year after transplantation is effective and may eliminate most cases of posttransplantation zoster. For further discussion, see Chap. 81. Cytomegalovirus The onset of CMV disease (interstitial pneumonia, bone marrow suppression, graft failure, hepatitis/colitis) usually begins 30–90 days after transplantation, when the granulocyte count is adequate but immunologic reconstitution has not occurred. CMV disease rarely develops earlier than 14 days after transplantation and may become evident as late as 4 months after the procedure. It is of greatest concern in the second month after transplantation, particularly in allogeneic HSCT recipients. In cases in which the donor marrow is depleted of T cells (to prevent GVHD or eliminate a T-cell tumor), the disease may be manifested earlier. The use of alemtuzumab to prevent GVHD in nonmyeloablative transplantation has been associated with an increase in CMV disease. Patients who receive ganciclovir for prophylaxis, preemptive treatment, or treatment (see below) may develop recurrent CMV infection even later than 4 months after transplantation, as treatment appears to delay the development of the normal immune response to CMV infection. Although CMV disease may present as isolated fever, granulocytopenia, thrombocytopenia, or gastrointestinal disease, the foremost cause of death from CMV infection in the setting of hematopoietic stem-cell transplantation is pneumonia.


With the standard use of CMV-negative or filtered blood products, primary CMV infection should be a risk in allogeneic transplantation only when the donor is CMVseropositive and the recipient is CMV-seronegative. Reactivation disease or superinfection with another strain from the donor is also common in CMV-positive recipients, and most seropositive patients who undergo hematopoietic stem-cell transplantation excrete CMV, with or without clinical findings. Serious CMV disease is much more common among allogeneic than autologous recipients and is often associated with GVHD. In addition to pneumonia and marrow suppression (and, less often, graft failure), manifestations of CMV disease in HSCT recipients include fever with or without arthralgias, myalgias, hepatitis, and esophagitis. CMV ulcerations occur in both the lower and the upper gastrointestinal tract, and it may be difficult to distinguish diarrhea due to GVHD from that due to CMV infection. The finding of CMV in the liver of a patient with GVHD does not necessarily mean that CMV is responsible for hepatic enzyme abnormalities. It is interesting that the ocular and neurologic manifestations of CMV infections are uncommon in these patients. Management of CMV disease in HSCT recipients includes strategies directed at prophylaxis and preemptive therapy (suppression of silent replication) and at treatment of disease. Prophylaxis results in a lower incidence of disease at the cost of treating many patients who otherwise would not require therapy. Because of the high fatality rate associated with CMV pneumonia in these patients and the difficulty of early diagnosis of CMV infection, prophylactic IV ganciclovir (or oral valganciclovir) has been used in some centers and has been shown to abort CMV disease during the period of maximal vulnerability (from engraftment to day 120 after transplantation).


Ganciclovir also prevents HSV reactivation and reduces the risk of VZV reactivation; thus acyclovir prophylaxis should be discontinued when ganciclovir is administered.The foremost problem with the administration of ganciclovir relates to adverse effects, which include dose-related bone marrow suppression (thrombocytopenia, leukopenia, anemia, and pancytopenia). Because the frequency of CMV pneumonia is lower among autologous HSCT recipients (2–7%) than among allogeneic HSCT recipients (10–40%), prophylaxis in the former group will not become the rule until a less toxic oral antiviral agent becomes available. Promising new drugs that are now being assessed in clinical trials include maribavir, a benzimidazole ribonucleoside that inhibits a viral protein kinase activity (UL97). Like prophylaxis, preemptive treatment, which targets patients with polymerase chain reaction (PCR) evidence of CMV, entails the unnecessary treatment of many individuals (on the basis of a laboratory test that is not highly predictive of disease) with drugs that have adverse effects. Currently, because of the neutropenia associated with ganciclovir in HSCT recipients, a preemptive approach—that is, treatment of those patients in whose blood CMV is detected by an antigen or nucleic acid amplification test—is used at most centers.This approach is almost as effective as prophylaxis and causes less toxicity.


Quantitative viral load assays, which are not dependent on circulating polymorphonuclear leukocytes, have supplanted antigen-based assays and are used by most centers. A positive test (or increasing viral load) prompts the initiation of preemptive therapy.When prophylaxis or preemptive therapy is stopped, late disease may occur, although by then the patient is often equipped with improved graft function and is better able to combat disease. Treatment of CMV pneumonia in HSCT recipients (unlike that in other clinical settings) involves both IV immune globulin (IVIg) and ganciclovir. In patients who cannot tolerate ganciclovir, foscarnet is a useful alternative, although it may produce nephrotoxicity and electrolyte imbalance.When neither ganciclovir nor foscarnet is clinically tolerated, cidofovir can be used; however, its efficacy is less well established, and its side effects include nephrotoxicity. Case reports have suggested that the immunosuppressive agent leflunomide may be active in this setting, but controlled studies are lacking. Maribavir is under investigation for treatment as well as prophylaxis. Transfusion of CMV-specific T cells from the donor decreased viral load in a small series of patients; this result suggests that immunotherapy may play a role in the treatment of this disease in the future. For further discussion, see Chap. 83. Human Herpesviruses 6 and 7 HHV-6, the cause of roseola in children, is a ubiquitous herpesvirus that reactivates (as determined by quantitative plasma PCR) in ∼50% of HSCT recipients 2–4 weeks after transplantation. Reactivation is more common among patients requiring glucocorticoids for GVHD and among those receiving second transplants. Reactivation of HHV-6 (primarily type B) appears to be associated with delayed monocyte and platelet engraftment.


Although encephalitis developing after transplantation has been associated with HHV-6 in cerebrospinal fluid (CSF), the causality of the association is not well defined. In several cases, plasma viremia was detected long before the onset of encephalitis; nevertheless, patients with encephalitis did tend to have very high viral loads in plasma at the time of CNS illness. HHV-6 DNA is sometimes found in lung samples after transplantation. However, its role in pneumonitis is also unclear. Although HHV-6 has been shown to be susceptible to foscarnet (and possibly to ganciclovir) in vitro, the efficacy of antiviral treatment has not been well studied. Little is known about the related herpesvirus HHV-7 or its role in posttransplantation infection. For further discussion, see Chap. 83. Epstein-Barr Virus Primary EBV infection can be fatal to HSCT recipients; EBV reactivation can cause EBV–B-cell lymphoproliferative disease (EBV-LPD), which may also be fatal to patients taking immunosuppressive drugs. Latent EBV infection of B cells leads to several interesting phenomena in HSCT recipients. The marrow ablation that occurs as part of the HSCT procedure may sometimes eliminate latent EBV from the host. Infection can then be reacquired immediately after transplantation by transfer of infected donor B cells.


Rarely, transplantation from a seronegative donor may result in cure.The recipient is then at risk for a second primary infection. EBV-LPD can develop in the recipient’s B cells (if any survive marrow ablation) but is more likely to be a consequence of outgrowth of infected donor cells. Both lytic and latent EBV replication are more likely during immunosuppression (e.g., they are associated with GVHD and the use of antibodies to T cells). Although less likely in autologous transplantation, reactivation can occur in T-cell–depleted autologous recipients (e.g., patients being given antibodies to T cells for the treatment of a T-cell lymphoma with marrow depletion). EBV-LPD, which can become apparent as early as 1–3 months after engraftment, can cause high fevers and cervical adenopathy resembling the symptoms of infectious mononucleosis but more commonly presents as an extranodal mass.The incidence of EBV-LPD among allogeneic HSCT recipients is 0.6–1%, which contrasts with figures of ∼5% for renal transplant recipients and up to 20% for cardiac transplant patients. In all cases, EBV-LPD is more likely to occur with high-dose, prolonged immunosuppression, especially that caused by the use of antibodies to T cells, glucocorticoids, and calcineurin inhibitors (e.g., cyclosporine, FK506). PCR can be used to monitor EBV production after hematopoietic stem-cell transplantation. High or increasing viral loads predict an enhanced likelihood of developing EBV-LPD and should prompt rapid reduction of immunosuppression and search for a focus of disease.


If reduction of immunosuppression does not have the desired effect, administration of a monoclonal antibody to CD20 (rituximab or others) for the treatment of B-cell lymphomas that express this surface protein has elicited dramatic responses and currently constitutes first-line therapy for CD20-positive EBV-LPD. However, longterm suppression of new antibody responses accompanies therapy, and recurrences are not infrequent. Additional B-cell–directed antibodies, including anti-CD22, are under study. The role of antivirals is uncertain because no available agents have been documented to have activity against the different forms of latent EBV infection. Preventing lytic replication in these patients would theoretically produce a statistical decrease in the frequency of latent disease by decreasing the number of virions available to cause additional infection. In case reports and small animal studies, ganciclovir and/or high-dose zidovudine together with other agents has been used to eradicate EBV-LPD and CNS lymphomas, another EBV-associated complication of transplantation. Both interferon and retinoic acid have been employed in the treatment of EBV-LPD, as has IVIg, but no large prospective studies have assessed the efficacy of any of these agents. Several additional drugs are undergoing preclinical evaluation. Standard chemotherapeutic regimens have been used as a last resort, even though patients’ tolerance and longterm results have been disappointing. EBV-specific T cells generated from the donor have been used experimentally to prevent and to treat EBV-LPD in allogeneic recipients, and efforts are underway to increase the activity and specificity of ex vivo–generated T cells. For further discussion, see Chap. 82.


Human Herpesvirus 8 The EBV-related gammaherpesvirus KSHV, which is causally associated with Kaposi’s sarcoma, with primary effusion lymphoma, and with multicentric Castleman’s disease, has rarely resulted in disease in HSCT recipients, although some cases of virus-associated marrow aplasia have been reported in the peritransplantation period.The relatively low seroprevalence of KSHV in the population and the limited duration of profound T-cell suppression after hematopoietic stem-cell transplantation provide a probable explanation for the currently low incidence of KSHV disease. For further discussion, see Chap. 83. Other (Nonherpes) Viruses The diagnosis of pneumonia in HSCT recipients poses some special problems. Because patients have undergone treatment with multiple chemotherapeutic agents and sometimes irradiation, their differential diagnosis should include—in addition to bacterial and fungal pneumonia— CMV pneumonitis, pneumonia of other viral etiologies, parasitic pneumonia, diffuse alveolar hemorrhage, and chemical- or radiation-associated pneumonitis. Since fungi and viruses [e.g., influenza A and B viruses, respiratory syncytial virus (RSV), parainfluenza virus (types 1, 2, and 3), metapneumoviruses, and adenoviruses] are also causes of pneumonia in this setting, it is important to diagnose CMV specifically (see “Cytomegalovirus” earlier in the chapter).


M. tuberculosis has been an uncommon cause of pneumonia among HSCT recipients in Western countries (accounting for <0.1–0.2% of cases) but is common in Hong Kong (5.5%) and in countries where the prevalence of tuberculosis is high. The recipient’s exposure history is clearly critical in an assessment of posttransplantation infections. Both RSV and parainfluenza viruses, particularly type 3, can cause severe or even fatal pneumonia in HSCT recipients. Infections with both of these agents sometimes occur as disastrous nosocomial epidemics. Preemptive treatment of upper airway infection and therapy for established lower tract invasion with aerosolized ribavirin and/or the anti-RSV monoclonal antibody palivizumab have been reported to lessen the severity of RSV disease in some studies. (RespiGam, a polyclonal anti-RSV preparation, is no longer available.) However, no large prospective studies establishing the efficacy of these agents in HSCT recipients have been performed. Aerosolized ribavirin is difficult to administer.Antibody in particular may prove more active in immunocompromised hosts, but relevant evaluation is lacking. Influenza also occurs in HSCT recipients and generally mirrors the presence of infection in the community. Progression to pneumonia is more common when infection occurs early after transplantation and when the recipient is lymphopenic. Several drugs are available for the treatment of influenza. Amantadine and rimantadine have limited effects, primarily reducing symptoms and shortening the duration of illness caused by sensitive strains of influenza A virus.The neuraminidase inhibitors oseltamivir (oral) and zanamivir (aerosolized) are active against both influenza A virus and influenza B virus and are a reasonable treatment option. Parenteral forms of neuraminidase inhibitors are undergoing clinical trials. An important preventive measure is immunization of household members, hospital staff members, and other frequent contacts. Human metapneumovirus, a paramyxovirus, can sometimes cause severe pneumonia and respiratory failure in HSCT recipients; however, mild or even asymptomatic infection may be more common.


At present, the overall contribution of human metapneumovirus to the burden of lower respiratory tract disease in HSCT recipients is unknown. Adenovirus can be isolated from HSCT recipients at rates varying from 5–18%.Although hemorrhagic cystitis, pneumonia, gastroenteritis, and fatal disseminated infection have been reported, adenovirus infection, which (like CMV infection) usually occurs in the first or second month after transplantation, is often asymptomatic.A role for cidofovir therapy has been suggested, but the efficacy of this agent is unproven. Infections with parvovirus B19 (presenting as anemia or occasionally as pancytopenia) and enteroviruses (sometimes fatal) can occur. Parvovirus infection may possibly respond to IVIg (Chap. 85). Intranasal pleconaril, a capsidbinding agent, is being studied for the treatment of enterovirus infection. Rhinoviruses and coronaviruses are frequent copathogens in HSCT recipients; however, whether they independently contribute to significant pulmonary infection is not known. Rotaviruses are a common cause of gastroenteritis in these patients. The polyomavirus BK virus is found at high titers in the urine of patients who are profoundly immunosuppressed. BK viruria may be associated with hemorrhagic cystitis in these patients. Compared with the incidence among patients with impaired T-cell function due to HIV infection, progressive multifocal leukoencephalopathy caused by the related JC virus is rare among HSCT recipients (Chap. 29). When transmitted by mosquitoes or by blood transfusion,West Nile virus can cause encephalitis and death after hematopoietic stem-cell transplantation.


INFECTIONS IN SOLID ORGAN TRANSPLANT (SOT) RECIPIENTS

Morbidity and mortality among SOT recipients are reduced by the use of effective antibiotics.The organisms that cause acute infections in recipients of SOT are different from those that infect HSCT recipients because SOT recipients do not go through a period of neutropenia. As the transplantation procedure involves major surgery, however, SOT recipients are subject to infections at anastomotic sites and to wound infections. Compared with HSCT recipients, SOT patients are immunosuppressed for longer periods (often permanently). Thus they are susceptible to many of the same organisms as patients with chronically impaired T-cell immunity (Chap. 11, especially Table 11-1). During the early period (<1 month after transplantation), infections are most commonly caused by extracellular bacteria (staphylococci, streptococci, enterococci, E. coli, other gram-negative organisms), which often originate in surgical wound or anastomotic sites.The type of transplant largely determines the spectrum of infection. In subsequent weeks, the consequences of the administration of agents that suppress cell-mediated immunity become apparent, and acquisition or reactivation of viruses and parasites (from the recipient or from the transplanted organ) can occur. CMV infection is often a problem, particularly in the first 6 months after transplantation, and may present as severe systemic disease or as infection of the transplanted organ. HHV-6 reactivation (assessed by plasma PCR) occurs within the first 2–4 weeks after transplantation and may be associated with fever, leukopenia, and possibly encephalitis. Data suggest that replication of HHV-6 and HHV-7 may exacerbate CMV-induced disease.


CMV is associated not only with generalized immunosuppression, but also with organ-specific, rejectionrelated syndromes: glomerulopathy in kidney transplant recipients, bronchiolitis obliterans in lung transplant recipients, vasculopathy in heart transplant recipients, and the vanishing bile duct syndrome in liver transplant recipients. A complex interplay between increased CMV replication and enhanced graft rejection is well established: Increasing immunosuppression leads to increased CMV replication, which is associated with graft rejection. For this reason, considerable attention has been focused on the diagnosis, prophylaxis, and treatment of CMV infection in SOT recipients. Early transmission of West Nile virus to transplant recipients from an organ donor has been reported; however, the risk of West Nile acquisition has been reduced by implementation of screening procedures. Beyond 6 months after transplantation, infections characteristic of patients with defects in cell-mediated immunity—e.g., infections with Listeria, Nocardia, Rhodococcus, various fungi, and other intracellular pathogens—may be a problem. International patients and global travelers may experience reactivation of dormant infections with trypanosomes, Leishmania, Plasmodium, Strongyloides, and other parasites. Elimination of these late infections will not be possible until the patient develops specific tolerance to the transplanted organ in the absence of drugs that lead to generalized immunosuppression. Meanwhile, vigilance, prophylaxis/preemptive therapy (when indicated), and rapid diagnosis and treatment of infections can be lifesaving in SOT recipients, who, unlike most HSCT recipients, continue to be immunosuppressed. SOT recipients are susceptible to EBV-LPD from as early as 2 months to many years after transplantation.


The prevalence of this complication is increased by potent and prolonged use of T-cell–suppressive drugs. Decreasing the degree of immunosuppression may in some cases reverse the condition. Among SOT patients, those with heart and lung transplants—who receive the most intensive immunosuppressive regimens—are most likely to develop EBV-LPD, particularly in the lungs. Although the disease usually originates in recipient B cells, several cases of donor origin, particularly in the transplanted organ, have been noted. High organ-specific content of B lymphoid tissues (e.g., bronchial-associated lymphoid tissue in the lung), anatomic factors (e.g., lack of access of host T cells to the transplanted organ because of disturbed lymphatics), and differences in major histocompatibility loci between the host T cells and the organ (e.g., lack of cell migration or lack of effective T-cell/ macrophage cooperation) may result in defective elimination of EBV-infected B cells. SOT recipients are also highly susceptible to the development of Kaposi’s sarcoma and less frequently to the B-cell proliferative disorders associated with KSHV, such as primary effusion lymphoma and multicentric Castleman’s disease. Kaposi’s sarcoma is much more common (in fact, 550–1000 times more common than in the general population), can develop very rapidly after transplantation, and can also occur in the allograft.However, because the seroprevalence of KSHV is very low in Western countries, Kaposi’s sarcoma is not often observed.


KIDNEY TRANSPLANTATION (See Table 12-4)

Early Infections Bacteria often cause infections that develop in the period immediately after kidney transplantation. There is a role for perioperative antibiotic prophylaxis, and many centers give cephalosporins to decrease the risk of postoperative complications. Urinary tract infections developing soon after transplantation are usually related to anatomic alterations resulting from surgery. Such early infections may require prolonged treatment (e.g., 6 weeks of antibiotic administration for pyelonephritis). Urinary tract infections that occur >6 months after transplantation may be treated for shorter periods because they do not seem to be associated with the high rate of pyelonephritis or relapse seen with infections that occur in the first 3 months. Prophylaxis with TMP-SMX [1 double-strength tablet (800 mg of sulfamethoxazole, 160 mg of trimethoprim) per day] for the first 4–6 months after transplantation decreases the incidence of early and middle-period infections (see below,Table 12-4, and Table 12-5). Middle-Period Infections Because of continuing immunosuppression, kidney transplant recipients are predisposed to lung infections characteristic of those in patients with T-cell deficiency (i.e., infections with intracellular bacteria, mycobacteria, nocardiae, fungi, viruses, and parasites).The high mortality rates associated with Legionella pneumophila infection (Chap. 49) led to the closing of renal transplant units in hospitals with endemic legionellosis. About 50% of all renal transplant recipients presenting with fever 1–4 months after transplantation have evidence of CMV disease; CMV itself accounts for the fever in more than two-thirds of cases and thus is the predominant pathogen during this period. CMV infection (Chap. 83) may also present as arthralgias, myalgias, or organ-specific symptoms.


During this period, this infection may represent primary disease (in the case of a seronegative recipient of a kidney from a seropositive donor) or may represent reactivation disease or superinfection. Patients may have atypical lymphocytosis. Unlike immunocompetent patients, however, they often do not have lymphadenopathy or splenomegaly.Therefore, clinical suspicion and laboratory confirmation are necessary for diagnosis.The clinical syndrome may be accompanied by bone marrow suppression (particularly leukopenia). CMV also causes glomerulopathy and is associated with an increased incidence of other opportunistic infections. Because of the frequency and severity of disease, a considerable effort has been made to prevent and treat CMV infection in renal transplant recipients. An immune globulin preparation enriched with antibodies to CMV was used by many centers in the past in an effort to protect the group at highest risk for severe infection (seronegative recipients of seropositive kidneys). However, with the development of highly effective oral antiviral agents, CMV immune globulin is no longer used. Ganciclovir (valganciclovir) is beneficial when prophylaxis is indicated and for the treatment of serious CMV disease. One study showed a significant (50%) reduction in CMV disease and rejection at 6 months among patients who received prophylactic valacyclovir (an acyclovir congener) for the first 90 days after renal transplantation. Acyclovir (valacyclovir) is less efficacious, but is also less toxic than ganciclovir (valganciclovir).


The availability of valganciclovir and valacyclovir has allowed most centers to move to oral prophylaxis for transplant recipients. Additional oral prophylactic agents, such as maribavir, are in clinical study. Infection with the other herpes-group viruses may become evident within 6 months after transplantation or later. Early after transplantation, HSV may cause either oral or anogenital lesions that are usually responsive to acyclovir. Large ulcerating lesions in the anogenital area may lead to bladder and rectal dysfunction as well as predisposing to bacterial infection.VZV may cause fatal disseminated infection in nonimmune kidney transplant recipients, but in immune patients, reactivation zoster usually does not disseminate outside the dermatome; thus disseminated VZV infection is a less fearsome complication in kidney transplantation than in hematopoietic stemcell transplantation. HHV-6 reactivation may take place and (although usually asymptomatic) may be associated with fever, rash, marrow suppression, or encephalitis. EBV disease is more serious; it may present as an extranodal proliferation of B cells that invade the CNS, nasopharynx, liver, small bowel, heart, and other organs, including the transplanted kidney.The disease is diagnosed by the finding of a mass of proliferating EBV-positive B cells.


The incidence of EBV-LPD is higher among patients who acquire EBV infection from the donor and among patients given high doses of cyclosporine, FK506, glucocorticoids, and anti–T-cell antibodies. Disease may regress once immunocompetence is restored. KSHV infection can be transmitted with the donor kidney, although it more often represents latent infection of the recipient. Kaposi’s sarcoma often appears within 1 year after transplantation, although the range of onset is wide (1 month to ∼20 years).Avoidance of immunosuppressive agents that inhibit calcineurin has been associated with less outgrowth of EBV and less CMV replication. The use of rapamycin (sirolimus) has led to regression of Kaposi’s sarcoma. The papovaviruses BK virus and JC virus (polyomavirus hominis types 1 and 2) have been cultured from the urine of kidney transplant recipients (as they have from that of HSCT recipients) in the setting of profound immunosuppression. High levels of BK virus replication detected by PCR in urine and blood are predictive of pathology, particularly in the setting of renal transplantation. Excretion of BK virus and BK viremia are associated with the development of ureteral strictures, polyomavirus-associated nephropathy (1–10% of renal transplant recipients), and (less commonly) generalized vasculopathy.Timely reduction of immunosuppression is critical and can reduce rates of graft loss related to polyomavirus-associated nephropathy from 90% to 10–30%. A possible role for treatment with cidofovir (given by the IV route and by bladder instillation), leflunomide, quinolones, and (most recently) lactoferrin has been reported, but the efficacy of these agents has not been substantiated through adequate clinical study. JC virus is associated with rare cases of progressive multifocal leukoencephalopathy.


Adenoviruses may persist with continued immunosuppression in these patients, but disseminated disease like that which occurs in HSCT recipients is much less common. Kidney transplant recipients are also subject to infections with other intracellular organisms. These patients may develop pulmonary infections with Nocardia, Aspergillus, and Mucor as well as infections with other pathogens in which the T-cell/macrophage axis plays an important role. In patients without IV catheters, L. monocytogenes is a common cause of bacteremia ≥1 month after renal transplantation and should be seriously considered in renal transplant recipients presenting with fever and headache. Kidney transplant recipients may develop Salmonella bacteremia, which can lead to endovascular infections and require prolonged therapy. Pulmonary infections with Pneumocystis are common unless the patient is maintained on TMP-SMX prophylaxis. Nocardia infection (Chap. 63) may present in the skin, bones, and lungs or in the CNS, where it usually takes the form of single or multiple brain abscesses. Nocardiosis generally occurs ≥1 month after transplantation and may follow immunosuppressive treatment for an episode of rejection. Pulmonary findings are nonspecific: localized disease with or without cavities is most common, but the disease may disseminate.


The diagnosis is made by culture of the organism from sputum or from the involved nodule.As with Pneumocystis, prophylaxis with TMP-SMX is often efficacious in the prevention of disease.The occurrence of Nocardia infections >2 years after transplantation suggests that a long-term prophylactic regimen may be justified. Toxoplasmosis can occur in seropositive patients but is less common than in other transplant settings, usually developing in the first few months after kidney transplantation. Again,TMP-SMX is helpful in prevention. In endemic areas, histoplasmosis, coccidioidomycosis, and blastomycosis may cause pulmonary infiltrates or disseminated disease. Late Infections Late infections (>6 months after kidney transplantation) may involve the CNS and include CMV retinitis as well as other CNS manifestations of CMV disease. Patients (particularly those whose immunosuppression has been increased) are at risk for subacute meningitis due to Cryptococcus neoformans. Cryptococcal disease may present in an insidious manner (sometimes as a skin infection before the development of clear CNS findings). Listeria meningitis may have an acute presentation and requires prompt therapy to avoid a fatal outcome. Patients who continue to take glucocorticoids are predisposed to ongoing infection.“Transplant elbow” is a recurrent bacterial infection in and around the elbow that is thought to result from a combination of poor tensile strength of the skin of steroid-treated patients and steroid-induced proximal myopathy that requires patients to push themselves up with their elbows to get out of chairs.


Bouts of cellulitis (usually caused by S. aureus) recur until patients are provided with elbow protection. Kidney transplant recipients are susceptible to invasive fungal infections, including those due to Aspergillus and Rhizopus, which may present as superficial lesions before dissemination. Mycobacterial infection (particularly that with Mycobacterium marinum) can be diagnosed by skin examination. Infection with Prototheca wickerhamii (an achlorophyllic alga) has been diagnosed by skin biopsy. Warts caused by human papillomaviruses (HPVs) are a late consequence of persistent immunosuppression; imiquimod or other forms of local therapy are usually satisfactory. Although BK virus replication and virus-associated disease can be detected far earlier, the median time to clinical diagnosis of polyomavirus-associated nephropathy is ∼300 days, qualifying it as a late-onset disease.With establishment of better screening procedures (e.g., blood PCR), it is likely that this disease will be detected earlier (see “Middle-Period Infections” earlier in the chapter).


HEART TRANSPLANTATION

Early Infections Sternal wound infection and mediastinitis are early complications of heart transplantation. An indolent course is common, with fever or a mildly elevated white blood cell count preceding the development of site tenderness or drainage. Clinical suspicion based on evidence of sternal instability and failure to heal may lead to the diagnosis. Common microbial residents of the skin (e.g., S. aureus, including methicillin-resistant strains, and Staphylococcus epidermidis) as well as gram-negative organisms (e.g., Pseudomonas aeruginosa) and fungi (e.g., Candida) are often involved. In rare cases, mediastinitis in heart transplant recipients can also be due to Mycoplasma hominis (Chap. 76). Since this organism requires an anaerobic environment for growth and may be difficult to see on conventional medium, the laboratory should be alerted that M. hominis infection is suspected. M. hominis mediastinitis has been cured with a combination of surgical debridement (sometimes requiring muscle-flap placement) and the administration of clindamycin and tetracycline. Organisms associated with mediastinitis may be cultured from accompanying pericardial fluid. Middle-Period Infections T. gondii (Chap. 121) residing in the heart of a seropositive donor may be transmitted to a seronegative recipient.


Thus serologic screening for T. gondii infection is important before and in the months after cardiac transplantation. Rarely, active disease can be introduced at the time of transplantation. The overall incidence of toxoplasmosis is so high in the setting of heart transplantation that some prophylaxis is always warranted.Although alternatives are available, the most frequently used agent is TMP-SMX, which prevents infection with Pneumocystis as well as with Nocardia and several other bacterial pathogens. CMV also has been transmitted by heart transplantation. CNS infections can be caused by Toxoplasma, Nocardia, and Aspergillus. L. monocytogenes meningitis should be considered in heart transplant recipients with fever and headache.  CMV infection is associated with poor outcomes after heart transplantation.The virus is usually cultivable 1–2 months after transplantation, causes early signs and laboratory abnormalities (usually fever and atypical lymphocytosis or leukopenia and thrombocytopenia) at 2–3 months, and can produce severe disease (e.g., pneumonia) at 3–4 months. Seropositive recipients usually develop cultivable virus faster than patients whose primary CMV infection is a consequence of transplantation. Between 40 and 70% of patients develop symptomatic CMV disease in the form of (1) CMV pneumonia, the most likely form to be fatal; (2) CMV esophagitis and gastritis, sometimes accompanied by abdominal pain with or without ulcerations and bleeding; and (3) the CMV syndrome, consisting of CMV in the blood along with fever, leukopenia, thrombocytopenia, and hepatic enzyme abnormalities. Ganciclovir is efficacious in the treatment of CMV infection; prophylaxis with ganciclovir or possibly with other antiviral agents, as described for renal transplantation, may reduce the overall incidence of CMVrelated disease. When prophylaxis is stopped, late-onset disease may occur. In fact, because of the expanded use of prophylaxis, this scenario is increasingly common, particularly in patients with ongoing GVHD.


Late Infections EBV infection usually presents as a lymphoma-like proliferation of B cells late after heart transplantation, particularly in patients maintained on intense immunosuppressive therapy. A subset of heart and heart-lung transplant recipients may develop early fulminant EBV-LPD (within 2 months).Treatment includes the reduction of immunosuppression (if possible), the use of glucocorticoid and calcineurin inhibitor–sparing regimens, and the consideration of therapy with anti–B-cell antibodies (rituximab and possibly others). Immunomodulatory and antiviral agents continue to be studied, and aggressive chemotherapy is a last resort, as discussed earlier for HSCT recipients. KSHV-associated disease, including Kaposi’s sarcoma and primary effusion lymphoma, has been reported in heart transplant recipients. Treatment with rapamycin (sirolimus) may prevent both rejection and outgrowth of KSHV-infected cells. Prophylaxis for Pneumocystis infection is required for these patients (see “Lung Transplantation, Late Infections” later in the chapter).


LUNG TRANSPLANTATION

Early Infections It is not surprising that lung transplant recipients are predisposed to the development of pneumonia.The combination of ischemia and the resulting mucosal damage, together with accompanying denervation and lack of lymphatic drainage, probably contributes to the high rate of pneumonia (66% in one series).The prophylactic use of high doses of broad-spectrum antibiotics for the first 3–4 days after surgery may decrease the incidence of pneumonia. Gram-negative pathogens (Enterobacteriaceae and Pseudomonas species) are troublesome in the first 2 weeks after surgery (the period of maximal vulnerability). Pneumonia can also be caused by Candida (possibly as a result of colonization of the donor lung), Aspergillus, and Cryptococcus. Mediastinitis may occur at an even higher rate among lung transplant recipients than among heart transplant recipients and most commonly develops within 2 weeks of surgery. In the absence of prophylaxis, pneumonitis due to CMV (which may be transmitted as a consequence of transplantation) usually presents between 2 weeks and 3 months after surgery, with primary disease occurring later than reactivation disease. Middle-Period Infections The incidence of CMV infection, either reactivated or primary, is 75–100% if either the donor or the recipient is seropositive for CMV.


CMV-induced disease appears to be most severe in recipients of lung and heart-lung transplants.Whether this severity relates to the mismatch in lung antigen-presenting and host immune cells or is attributable to other (nonimmunologic) factors is not known. More than half of lung transplant recipients with symptomatic CMV disease have pneumonia. Difficulty in distinguishing the radiographic picture of CMV infection from other infections and organ rejection further complicates therapy. CMV can also cause bronchiolitis obliterans in lung transplants.The development of pneumonitis related to HSV has led to the prophylactic use of acyclovir. Such prophylaxis may also decrease rates of CMV disease, but ganciclovir is more active against CMV and is also active against HSV. The prophylaxis of CMV infection with IV ganciclovir—or increasingly with valganciclovir, the oral alternative—is recommended for lung transplant recipients. Antiviral alternatives are discussed in the earlier section on hematopoietic stem-cell transplantation. Although the overall incidence of serious disease is decreased during prophylaxis, late disease may occur when prophylaxis is stopped—a pattern observed increasingly in recent years. With recovery from peritransplantation complications and, in many cases, a decrease in immunosuppression, the recipient is often better equipped to combat late infection.


Late Infections The incidence of Pneumocystis infection (which may present with a paucity of findings) is high among lung and heart-lung transplant recipients. Some form of prophylaxis for Pneumocystis pneumonia is indicated in all organ transplant situations (Table 12-5). Prophylaxis with TMPSMX for 12 months after transplantation may be sufficient to prevent Pneumocystis disease in patients whose degree of immunosuppression is not increased. As in other transplant recipients, infection with EBV may cause either a mononucleosis-like syndrome or EBV-LPD.The tendency of the B-cell blasts to present in the lung appears to be greater after lung transplantation than after the transplantation of other organs. Reduction of immunosuppression and switching of regimens, as discussed in earlier sections, causes remission in some cases, but airway compression can be fatal, and more rapid intervention may therefore become necessary.The approach to EBV-LPD is similar to that described in other sections.


LIVER TRANSPLANTATION

Early Infections As in other transplantation settings, early bacterial infections are a major problem after liver transplantation. Many centers administer systemic broad-spectrum antibiotics for the first 24 h or sometimes longer after surgery, even in the absence of documented infection. However, despite prophylaxis, infectious complications are common and are correlated with the duration of the surgical procedure and the type of biliary drainage.An operation lasting >12 h is associated with an increased likelihood of infection. Patients who have a choledochojejunostomy with drainage of the biliary duct to a Roux-en-Y jejunal bowel loop have more fungal infections than those whose bile is drained via a choledochocholedochostomy with anastomosis of the donor common bile duct to the recipient common bile duct. Peritonitis and intraabdominal abscesses are common complications of liver transplantation. Bacterial peritonitis or localized abscesses may result from biliary leaks. Early leaks are even more common (incidence, ∼17%) with live-donor liver transplants (LDLTs). Peritonitis in liver transplant recipients is often polymicrobial, commonly involving enterococci, aerobic gram-negative bacteria, staphylococci, anaerobes, Candida, or other invasive fungi. Only one-third of patients with intraabdominal abscesses have bacteremia. Abscesses within the first month after surgery may occur not only in and around the liver, but also in the spleen, pericolic area, and pelvis. Treatment includes antibiotic administration and drainage as necessary.


Liver transplant patients have a high incidence of fungal infections, and the occurrence of fungal (often candidal) infection is correlated with preoperative use of glucocorticoids, long duration of treatment with antibacterial agents, and posttransplantation use of immunosuppressive agents. Middle-Period Infections The development of postsurgical biliary stricture predisposes patients to cholangitis.The incidence of strictures is increased in LDLT (∼17% of liver transplant recipients); therefore, cholangitis is also more common among these patients. Transplant recipients who develop cholangitis may have high spiking fevers and rigors but often lack the characteristic signs and symptoms of classic cholangitis, including abdominal pain and jaundice. Although these findings may suggest graft rejection, rejection is typically accompanied by marked elevation of liver function enzymes. In contrast, in cholangitis in transplant recipients, results of liver function tests (with the possible exception of alkaline phosphatase levels) are often within the normal range.


Definitive diagnosis of cholangitis in liver transplant recipients requires documentation of bacteremia or demonstration of aggregated neutrophils in bile duct biopsy specimens. Unfortunately, invasive studies of the biliary tract (either T-tube cholangiography or endoscopic retrograde cholangiopancreatography) may themselves lead to cholangitis. For this reason, many clinicians recommend an empirical trial of therapy with antibiotics covering gram-negative organisms and anaerobes before these procedures are undertaken, as well as antibiotic coverage if they are eventually performed. Reactivation of viral hepatitis is a common complication of liver transplantation (Chap. 92). Recurrent hepatitis B and C infections, for which transplantation may be performed, are problematic.To prevent hepatitis B virus reinfection, prophylaxis with an optimal antiviral agent or combination of agents (lamivudine, adefovir, entecavir) and hepatitis B immune globulin is currently recommended, although the optimal dose, route, and duration of therapy remain controversial. Success in preventing reinfection with hepatitis B virus has increased in recent years; in contrast, reinfection of the graft with hepatitis C virus occurs in all patients, with a variable time frame. Studies of aggressive pretransplantation treatment of selected recipients with antiviral agents and prophylactic/preemptive regimens are ongoing. However, early initiation of treatment for histologically documented disease with a combination of ribavirin and pegylated interferon has produced sustained responses at rates in the range of 25–40%. As in other transplantation settings, reactivation disease with herpes-group viruses is common (Table 12-3).


Herpesviruses can be transmitted in donor organs. Although CMV hepatitis occurs in ∼4% of liver transplant recipients, it is usually not so severe as to require retransplantation. Without prophylaxis, CMV disease develops in the majority of seronegative recipients of organs from CMVpositive donors, but fatality rates are lower among liver transplant recipients than among lung or heart-lung transplant recipients. Disease due to CMV can also be associated with the vanishing bile duct syndrome after liver transplantation. Patients respond to treatment with ganciclovir; prophylaxis with oral forms of ganciclovir or high-dose acyclovir may decrease the frequency of disease. A role for HHV-6 reactivation in posttransplantation fever and leukopenia has been proposed, although the more severe sequelae described in hematopoietic stemcell transplantation are unusual. HHV-6 and HHV-7 appear to exacerbate CMV disease in this setting. EBVLPD after liver transplantation shows a propensity for involvement of the liver, and such disease may be of donor origin. See previous sections for discussion of EBV infections in solid organ transplantation.


PANCREAS TRANSPLANTATION

Transplantation of the pancreas can be complicated by early bacterial and yeast infections. Most pancreatic transplants are drained into the bowel, whereas the remaining transplants (∼20%) are drained into the bladder.A cuff of duodenum is used in the anastomosis between the pancreatic graft and either the gut or the bladder. Bowel drainage poses a risk of early abdominal and allograft infections with enteric bacteria and yeasts.These infections often result in loss of the graft. Bladder drainage causes a high rate of urinary tract infection and sterile cystitis; however, infection can usually be cured with appropriate antimicrobial agents. In both procedures, prophylactic antimicrobial agents are commonly used at the time of surgery. An alternative method—the transplantation of islet cells only—may eliminate the problems characteristically posed by wound and urinary tract sepsis in pancreatic transplant recipients. Issues related to the development of CMV infection, EBV-LPD, and infections with opportunistic pathogens in patients receiving a pancreatic transplant are similar to those in other SOT recipients.


MISCELLANEOUS INFECTIONS IN SOLID ORGAN TRANSPLANTATION

Indwelling IV Catheter Infections The prolonged use of indwelling IV catheters for administration of medications, blood products, and nutrition is common in diverse transplantation settings and poses a risk of local and bloodstream infections. Significant insertion-site infection is most commonly caused by S. aureus. Bloodstream infection most frequently develops within a week of catheter placement or in patients who become neutropenic. Coagulase-negative staphylococci are the most common isolates from the blood. For further discussion of differential diagnosis and therapeutic options, see Chap. 11. Tuberculosis The incidence of tuberculosis occurring within the first 12 months after solid organ transplantation is greater than that observed after hematopoietic stem-cell transplantation (0.23–0.79%) and ranges broadly worldwide (1.2–15%), reflecting the prevalences of tuberculosis in local populations. Lesions suggesting prior tuberculosis on chest x-ray, older age, diabetes, chronic liver disease,GVHD, and intense immunosuppression are predictive of tuberculosis reactivation and development of disseminated disease in a host with latent disease.Tuberculosis has rarely been transmitted from the donor organ. In contrast to the low mortality rate among HSCT recipients, mortality rates among SOT patients are reported to be as high as 30%.Vigilance is indicated, as the presentation of disease is often extrapulmonary (gastrointestinal, genitourinary, central nervous, endocrine, musculoskeletal, laryngeal) and atypical, sometimes manifesting as a fever of unknown origin.


A careful history and a direct evaluation of both the recipient and the donor before transplantation are optimal. Skin testing of the recipient with PPD may be unreliable because of chronic disease and/or immunosuppression, but newer cell-based assays that measure interferon and/or cytokine production may prove more sensitive in the future. Isoniazid toxicity has not been a significant problem except in the setting of liver transplantation. Therefore, appropriate prophylaxis should proceed. An assessment of the need to treat latent disease should include careful consideration of the possibility of a false-negative test result. Pending final confirmation of suspected tuberculosis, aggressive multidrug treatment in accordance with the guidelines of the Centers for Disease Control and Prevention (CDC), the Infectious Diseases Society of America, and the American Thoracic Society is indicated because of the high mortality rates among these patients. Altered drug metabolism (e.g., upon co-administration of rifampin and certain immunosuppressive agents) can be managed with careful monitoring of drug levels and appropriate dose adjustment. Close follow-up of hepatic enzymes is warranted, particularly during treatment with isoniazid, pyrazinamide, and/or rifampin. Drug-resistant tuberculosis is especially problematic in these individuals (Chap. 66).


Virus-Associated Malignancies In addition to malignancy associated with gammaherpesvirus infection (EBV, KSHV) and simple warts (HPV), other tumors that are virus-associated or suspected of being virus-associated are more likely to develop in transplant recipients, particularly those who require long-term immunosuppression, than in the general population.The interval to tumor development is usually >1 year.Transplant recipients develop nonmelanoma skin or lip cancers that, in contrast to de novo skin cancers, have a high ratio of squamous cells to basal cells. HPV may play a major role in these lesions. Cervical and vulvar carcinomas, quite clearly associated with HPV, develop with increased frequency in female transplant recipients.Among renal transplant recipients, rates of melanoma are modestly increased, and rates of cancers of the kidney and bladder are increased.


VACCINATION OF TRANSPLANT RECIPIENTS

In addition to receiving antibiotic prophylaxis, transplant recipients should be vaccinated against likely pathogens (Table 12-6). In the case of HSCT recipients, optimal responses cannot be achieved until after immune reconstitution, despite previous immunization of both donor and recipient. Recipients of allogeneic HSCTs must be reimmunized if they are to be protected against pathogens. The situation is less clear-cut in the case of autologous transplantation. T and B cells in the peripheral blood may reconstitute the immune response if they are transferred in adequate numbers. However, cancer patients (particularly those with Hodgkin’s disease, in whom vaccination has been extensively studied) who are undergoing chemotherapy do not respond normally to immunization, and titers of antibodies to infectious agents fall more rapidly than in healthy individuals. Therefore, even immunosuppressed patients who have not had HSCTs may need booster vaccine injections. If memory cells are specifically eliminated as part of a stem-cell “cleanup” procedure, it will be necessary to reimmunize the recipient with a new primary series. Optimal times for immunizations of different transplant populations are being evaluated.


Yearly immunization of household and other contacts (including health care personnel) against influenza benefits the patient by preventing local spread. In the absence of compelling data regarding optimal timing, it is reasonable to administer the pneumococcal and H. influenzae type b conjugate vaccines to both autologous and allogeneic HSCT recipients beginning 12 months after transplantation.A series that includes both the 7-valent pneumococcal conjugate vaccine and the 23-valent Pneumovax is now recommended (following CDC guidelines). The pneumococcal and H. influenzae type b vaccines are particularly important for patients who have undergone splenectomy. In addition, diphtheria, tetanus, acellular pertussis, and inactivated polio vaccines can all be given at these same intervals (12 months and, as required, 24 months after transplantation). Neisseria meningitidis polysaccharide (a new conjugate vaccine) is now available and will probably be recommended in the future. Some authorities recommend a new primary series for tetanus/ diphtheria/pertussis and inactivated polio vaccine beginning 12 months after transplantation.


Because of the risk of spread, household contacts of HSCT recipients (or of patients immunosuppressed as a result of chemotherapy) should receive only inactivated polio vaccine. Live-virus measles/mumps/rubella vaccine can be given to autologous HSCT recipients 24 months after transplantation and to most allogeneic HSCT recipients at the same point if they are not receiving maintenance therapy with immunosuppressive drugs and do not have ongoing GVHD. The risk of spread from a household contact is lower for MMR vaccine than for polio vaccine. Neither patients nor their household contacts should be vaccinated with vaccinia unless they have been exposed to the smallpox virus. Among patients who have active GVHD and/or are taking high maintenance doses of glucocorticoids, it may be prudent to avoid all live-virus vaccines. Vaccination to prevent hepatitis B and hepatitis A also seems advisable. In the case of SOT recipients, administration of all the usual vaccines and of the indicated booster doses should be completed before immunosuppression, if possible, to maximize responses. For patients taking immunosuppressive agents, the administration of pneumococcal vaccine should be repeated every 5 years. No data are available for the meningococcal vaccine, but it is probably reasonable to administer it along with the pneumococcal vaccine. H. influenzae conjugate vaccine is safe and should be efficacious in this population; therefore, its administration before transplantation is recommended. Booster doses of this vaccine are not recommended for adults.


SOT recipients who continue to receive immunosuppressive drugs should not receive live-virus vaccines. A person in this group who is exposed to measles should be given immune globulin. Similarly, an immunocompromised patient who is seronegative for varicella and who comes into contact with a person who has chickenpox should be given varicella-zoster immune globulin as soon as possible (and certainly within 96 h) or, if this is not possible, should be started immediately on a 10- to 14-day course of acyclovir therapy. Upon the discontinuation of treatment, clinical disease may still occur in a small number of patients; thus vigilance is indicated. Rapid re-treatment should limit the symptoms of disease. Household contacts of transplant recipients can receive live attenuated VZV vaccine, but vaccinees should avoid direct contact with the patient if a rash develops. Virus-like particle (VLP) vaccines (not live attenuated) have recently been licensed for the prevention of infection with several HPV serotypes most commonly implicated in cervical and anal carcinomas and in anogenital and laryngeal warts. For example, the tetravalent vaccine contains HPV serotypes 6, 11, 16, and 18. At present, no information is available about the safety, immunogenicity, or efficacy of this vaccine in transplant recipients. Immunocompromised patients who travel may benefit from some but not all vaccines (Chaps. 3 and 4).


In general, these patients should receive any killed or inactivated vaccine preparation appropriate to the area they are visiting; this recommendation includes the vaccines for Japanese encephalitis, hepatitis A and B, poliomyelitis, meningococcal infection, and typhoid.The live typhoid vaccines are not recommended for use in most immunocompromised patients, but inactivated or purified polysaccharide typhoid vaccine can be used. Live yellow fever vaccine should not be administered. On the other hand, primary immunization or boosting with the purified-protein hepatitis B vaccine is indicated if patients are likely to be exposed. Patients who will reside for >6 months in areas where hepatitis B is common (Africa, Southeast Asia, the Middle East, Eastern Europe, parts of South America, and the Caribbean) should receive hepatitis B vaccine. Inactivated hepatitis A vaccine should also be used in the appropriate setting (Chap. 3). A combined vaccine is now available that provides dual protection against hepatitis A and hepatitis B. If hepatitis A vaccine is not administered, travelers should consider receiving passive protection with immune globulin (the dose depending on the duration of travel in the high-risk area).  ​