Infections In Transplant Patients Research Articles

Cytological diagnosis of infections in renal allograft recipients

Infection is the most common cause of mortality and morbidity within the first year of transplantation. Renal allograft recipients are susceptible to various opportunistic infections because of prolonged immunosuppression. The study was carried out to evaluate the role of cytology for rapid diagnosis of infections in transplant patients. Fine needle aspiration cytology (FNAC) of superficial lesions, guided aspirations from deep seated lesions, bronchoalveolar lavage, endoscopic brushings and urine cytology was the material studied. 292 renal transplants were done during a period of nine years. 46 cases of infections were diagnosed, comprising of bacterial (26), viral (2), fungal (13) and mixed bacterial and fungal (5). Cytological examination offers a rapid and specific diagnosis of infections in these immunocompromised patients. The incidence, severity of infection and mortality in post transplant patients will decrease with early diagnosis and high index of clinical suspicion.

Hepatic gas gangrene following liver transplantation

A 45-year-old man presented with a 2-day history of diarrhea, fever, and progressing fatigue. The patient had undergone a liver transplantation for cryptogenic cirrhosis with Roux-en-Y hepaticojejunostomy 9 years earlier. No vascular complications had emerged in the posttransplant period. Immunosuppression was achieved initially with prednisolone and cyclosporine A, and was later switched to mycophenolate mofetil and prednisolone. Upon admission, the patient's blood pressure was 100/70 mm Hg, and his pulse was 115 beats per minute, with an oxygen saturation of 93% while breathing 6 liters of oxygen per minute through nasal cannula. Upon examination, the patient appeared somnolent, but his chest and abdomen were unremarkable. Laboratory investigations revealed procalcitonin of 56.8 μg/L, creatinine of 487 μmol/L, and aspartate aminotransferase of 1,502 U/L. Escherichia coli in the first blood culture prompted the administration of ceftriaxone plus metronidazole. A computed tomography scan of the abdomen revealed massive aerobilia (Fig. 1) and gas-filled cavity of the right hepatic lobe. During the next hours, the patient became anuric, and the hemodynamic situation deteriorated rapidly despite maximal treatment. Surgical debridement that might have ended up in hepatectomy was not regarded to be an option in the face of advanced multiorgan failure. The patient died shortly thereafter. A computed tomography scan of the abdomen revealing massive aerobilia (black arrow) and gas-filled cavity of the right hepatic lobe (white arrows). The postmortem examination revealed a large abscess formation within the right lobe of the liver, and portal-vein thrombosis. The necrotic hepatic parenchyma was infiltrated by gram-positive rods. Blood cultures tested positive for Clostridium perfringens shortly thereafter. C. perfringens is a member of the normal colonic flora. Spores in soil or food can enter the organism and cause food poisoning or gas gangrene with a high mortality rate.1C. perfringens appears as a short, plump, strongly gram-positive rod (2 to 4 μm long and 1 to 1.5 μm wide) that possesses a central or subterminal spore.2 Alpha toxin (phospholipase C) is one of at least 12 antigenic protein toxins of C. perfringens and induces hemolysis, platelet destruction, cardiogenic shock, and multiple organ failure.3 Spontaneous C. perfringens bacteremia has been associated with neoplastic diseases (mortality rate of 58% in a case series of 136 episodes) and liver cirrhosis (mortality rate of 30% in a case series of 73 episodes).4, 5 Hepatic involvement of C. perfringens infection can lead to pylephlebitis, which carries a bad prognosis and may come to attention by floating high amplitude ultrasound echoes within the extrahepatic and intrahepatic portal veins.6 In the current case, the cause of portal vein thrombosis, which was recognized post mortem but not seen on the initial computed tomography scan, remains unclear. The patient had not received vascular grafts during the transplantation. Moreover, the hepatic artery as well as the hepatic veins were patent on computed tomography imaging. Five cases of Clostridium infections following liver transplantation have recently been described in the literature.7-11 At least 2 patients died, another underwent immediate retransplantation. Although this strain of C. perfringens was sensitive to metronidazole, the antibiotic therapy was probably initiated too late to be effective. Broad-spectrum coverage with concomitant administration of penicillin G, aminoglycoside, and clindamycin is now recommended for C. perfringens infections.2, 12 Surgical debridement of all necrotic tissue should be performed immediately, and liver retransplantation has been suggested as a salvage therapy.10 The current case reminds us, however, that C. perfringens infections in transplant patients may come to attention too late to be effectively treated.

The debate: The trials have told us very little.

The original trials of empiric intravenous amphotericin-B in the 1980s failed to prove conclusively its efficacy in the treatment of febrile neutropenia. Despite that, all subsequent studies of the therapy of presumed, possible, probable and proven invasive aspergillosis have assumed that this drug, either as deoxycholate or in lipid-based form, is the gold standard treatment against which all newcomers should be compared. This has led to a series of further inconclusive randomized controlled trials of empiric therapy as a result of which the most we can say is that nearly all new drugs are less toxic but also no more effective than amphotericin-B deoxycholate. The toxicity of the non-lipid formulation of this drug should have led us to withdraw it from both RCTs and routine clinical practice some years ago in view of the increasing evidence of equivalent efficacy and lower toxicity of other agents including lipid amphotericin formulations.Recent studies of the use of newer diagnostic techniques (i.e., CT and serology) reinforce the need to abandon the empiric trial approach in which we have repeatedly shown lack of superiority in the treatment of an infection which most patients do not have. Even in the small number of trials of the therapy of proven or probable invasive aspergillosis, results have been inconclusive or at best confusing in trying to find a better option than amphotericin-B. The trial of voriconazole versus amphotericin-B deoxycholate for this indication is a model for study for all those interested in the difficulties of designing trials which lead to convincing results.Effective prophylaxis trials and their analyses began by following a more rational pathway, first showing convincingly that fluconazole reduced the risk of C. albicans systemic infection in transplant patients. Unfortunately the widespread faith in the ability of this drug to prevent a wider range of systemic fungal infections in a wider range of patients is simply not supported by the data from many subsequent single trials and meta-analyses. This attachment to fluconazole has been mirrored by unwillingness to accept the evidence that itraconazole is superior in prophylaxis to fluconazole which is inactive against Aspergillus spp. In this case the trials have not told us enough because we have not believed the results. Results of trials of extended range azoles such as posaconazole are interesting but there are insufficient data to claim that posaconazole is superior to itraconazole.The progress in therapy and prophylaxis of systemic fungal infection has been unsatisfactory and slow. A new approach is needed for the design of clinical trials for these indications. There is good evidence that supportive investigations should now be used routinely in clinical practice and trials to increase certainty about the presence of invasive infection, to limit unnecessary use of expensive and toxic drugs and to improve analysis of efficacy of old and new antifungal agents.

Tailoring immunosuppressants to hepatitis C virus–infected transplant patients

Hepatitis C virus (HCV) is the leading indication for liver transplant in the world. After transplantation, patients remain infected with HCV and are at high risk for recurrent end-stage liver disease. We will review retrospective and prospective studies, which suggest that specific immunosuppressive cocktails are more associated with severe recurrent HCV and relate these studies to in vitro analysis of the effect of immunosuppressants on HCV in vitro. Immunosuppressive antibodies and high-dose steroids have been associated with increased viral replication in the short term, and data also suggest worsening liver disease in the long term. On the other hand, mycophenolate mofetil, azathioprine, and cyclosporine have all been shown to have antiviral properties against HCV in in vitro studies. Although future research is desperately needed, a picture of how the risks and benefits of immunosuppressive regimens in HCV-infected patients differ from non–HCV-infected patients is emerging, and possible recipes for immunosuppressant cocktails tailored to limit HCV while still preventing graft rejection are contemplated.

The role of PCR in detection of cytomegalovirus in blood and urine of transplanted patients

Rapid and reliable laboratory diagnosis of cytomegalovirus (CMV) infection in transplanted patients becomes more significant considering possible prevention or moderation of CMV disease. The aim of this study was comparison of CMV isolation in cell culture and CMV detection by PCR in blood and urine samples of transplanted patients. The study comprised 21 patients undergoing immunosuppressive therapy after renal or bone marrow transplantation. MRC-5 cell culture was used for viral isolation. Inoculated cultures were maintained for 4 weeks or until appearance of specific cytopathic effect (CPE). Primers used in PCR were specific for the sequence within egzon 4 of immediate-early 1 (IE-1) gene. Presence of anti-CMV IgG and IgM antibodies was determined by ELISA. PCR was more sensitive for blood (4/21) and urine samples (3/19) than cell culture method--blood (0/21) urine (2/19). Statistically significant correlation was not shown between presence of CMV(determined by PCR) in blood and urine of the same patient.

Epstein–Barr viremia levels after pediatric liver transplantation as measured by real‐time polymerase chain reaction

Effective immunosuppression has improved the results following liver transplantation, but also increased the risk for opportunistic infections. Epstein-Barr virus (EBV) infection in transplant patients can cause various symptoms including the life-threatening premalignant condition, post-transplantation lymphoproliferative disorder (PTLD). Serum specimens from 24 consecutive children (mean 7.6 specimens/patient), who had undergone liver transplantation in Göteborg from January 1995 to May 2002, were analyzed retrospectively for EBV DNA by real-time TaqMan polymerase chain reaction (PCR). The results were related to clinical picture, immunosuppression, graft rejection and infections with other agents. Eleven patients (46%) developed primary EBV infection at a mean time of 4.8 months after transplantation, and six (25%) reactivated EBV infection at a mean of 4.0 months after transplantation. Four of the 11 patients with primary infection had symptomatic EBV infection: two had PTLD and two hepatitis. One patient in the group with reactivated infection developed PTLD. EBV DNA levels were significantly higher in the group with primary symptomatic infection compared with the patients with primary asymptomatic infection (mean 65 500 copies/mL; range 14 200-194 300 vs. 3700 copies/mL; range 100-9780). In patients with symptomatic infection EBV DNA levels did not differ between PTLD and hepatitis patients. The data suggest that quantitative analysis of EBV DNA in serum by real-time PCR is useful for identification of EBV-related disease.

Emerging viral infections in transplant recipients

Transplant patients are uniquely predisposed to emerging infections for a number of reasons. Two outbreaks, West Nile virus and severe acute respiratory syndrome, have recently provided important lessons on how transplant patients are affected, and how transplant programmes must adapt and evolve in the face of emerging infections. An update of emerging infections in transplant patients, using West Nile virus and severe acute respiratory syndrome as specific examples, is summarized here. Exogenous immunosuppression, specific allograft factors, and extensive contact with the healthcare system all predispose transplant patients to emerging infections. Transplant patients may acquire West Nile virus through blood transfusion, donor transmission, or community exposure. Seroprevalence data in transplant populations suggest the risk of severe neurological disease is several fold higher in transplant recipients who acquire West Nile virus compared with immunocompetent individuals. Prevention strategies are critical in this population. These include nucleic acid testing of blood products and potentially also screening organ donors in a similar manner. During the outbreak of severe acute respiratory syndrome, transplant patients with severe and rapidly progressive disease were reported. Higher viral burdens appeared to be present in transplant patients and may have implications for the increased infectivity of these patients. Transplant programmes in severe acute respiratory syndrome areas were also adversely affected because of donor concerns, recipient issues and resource problems. Transplant patients are uniquely predisposed to emerging infections. Lessons learned from West Nile virus and severe acute respiratory syndrome in transplantation should be applicable to future outbreaks of other emerging infectious diseases.

Changing face of health-care associated fungal infections

The purpose of this review was to evaluate recent publications on the epidemiology, diagnosis and management of invasive fungal infections. Epidemiological surveys have highlighted significant differences between Europe and the United States regarding the incidence and etiology of Candida bloodstream infections. Today, invasive aspergillosis is occurring in a much broader patient population than the classical immunocompromised hosts and includes mechanically ventilated intensive care unit patients and patients receiving corticosteroids for treatment of chronic lung diseases. Diagnosis is often delayed in these patients and prognosis is dismal. Measurement of galactomannan, mannan and antimannan antibodies, and beta-(1-3)-D-glucan may help to speed up diagnosis. The epidemiology of invasive mold infections is changing. The frequency of non-fumigatus Aspergillus species is increasing, uncommon hyalo-or phaeo-hyphomycoses are emerging and breakthrough mold infections intrinsically resistant to azoles have been reported. Clinical trials have shown that new azoles and echinocandins are as efficacious as amphotericin B or fluconazole for the treatment of eosophageal or invasive candidiasis, for prophylaxis of invasive fungal infections in transplant patients, or for empirical antifungal therapy in patients with persistent fever and neutropenia. Recent data suggest that the epidemiology of invasive fungal infections may be changing with the emergence of uncommon molds and the occurrence of invasive aspergillosis in 'nonclassical' immunocompromised hosts. New diagnostic tools and improved antifungal agents are available to facilitate early diagnosis and offer new treatment options.

Common viral infections in transplant recipients, part 1. herpesviruses (continued)

Herpesviruses are common opportunistic infections in transplant recipients. Recent diagnostic and therapeutic advances have improved the prognosis of these infections in transplant patients. Among these, the introduction of quantitative PCR and other molecular assays, dissemination of antiviral susceptibility tests, and upgrading of serologic tests represent the most significant diagnostic improvements in the last 10 years. The use of pre-emptive and prophylactic therapies, coupled with the availability of new oral antivirals, represents the most significant change in the treatment arena.

Common viral infections in transplant recipients, part 1. Herpesviruses

Abstract Herpesviruses are common opportunistic infections in transplant recipients. Recent diagnostic and therapeutic advances have improved the prognosis of these infections in transplant patients. Among these, the introduction of quantitative PCR and other molecular assays, dissemination of antiviral susceptibility tests, and upgrading of serologic tests represent the most significant diagnostic improvements in the last 10 years. The use of pre-emptive and prophylactic therapy, coupled with the availability of new oral antivirals, represents the most significant change in the treatment arena.

Monitoring for human cytomegalovirus infection in solid organ transplant recipients through antigenemia and glycoprotein N (gN) variants: evidence of correlation and potential prognostic value of gN genotypes

Human cytomegalovirus (HCMV) ORF UL73 encodes the envelope glycoprotein gpUL73-gN, which shows seven genotypes (gN-1, gN-2, gN-3a, gN-3b, gN-4a, gN-4b, gN-4c). The goal of this study was to determine retrospectively the distribution of gN variants in solid organ transplant recipients with HCMV infection and to establish an association with parameters important for monitoring post-transplantation clinical course during a follow-up of up to 2 years. Peripheral blood leukocytes from 40 solid organ transplant recipients were analysed for pp65-antigen by immunofluorescence and gN genotyped by sequencing or RFLP analysis. A correlation between gN genotypes and antigenemia peak was found, showing a highly significant difference between gN-1 and gN-4b variants ( P < 0.005). In particular, gN-1 seems to be associated with patients developing low level antigenemia (<50 pp65-positive cells/2 × 10 5 PBLs; PPV = 90%), whereas gN-4b predicts significantly higher values (>50 pp65-positive cells/2 × 10 5 PBLs; PPV = 80%). Furthermore, the onset of positive antigenemia is significantly earlier in patients infected with a gN-4b strain, compared with those infected by a gN-1 variant. Reported data further support a role for gN genotypes in HCMV pathogenesis. gN-1 and gN-4b show a significantly different virulence and could serve as early predictors for the progression of HCMV infection in transplant patients.

A survey of dental care protocols among US organ transplant centers

Untreated dental disease represents a potential risk for infection in transplant patients, but the vast transplantation literature has few references to this complication. There is also little information with regard to dental care protocols for patients before and after organ transplantation. To obtain more definitive documentation about the policies that deal with dental care and experience with dental infections, we conducted a survey of US transplant centers. The instrument consisted of eight questions that addressed pre-transplant dental evaluation procedures, incidence of pre- and post-transplant dental infections, and recommendations for antibiotic prophylaxis with dental treatment after transplantation. Questionnaires were sent to 768 medical and/or surgical directors at all US transplant centers. Responses were received from 294 recipients (38%). Among the respondents, 80% routinely requested a pre-transplant dental evaluation, but 49% of these were only for specific organs. The occurrence of a dental infection prior to transplantation that resulted in a postponement or cancellation was reported by 38% of the respondents. Post-transplantation sepsis from a suspected dental source was acknowledged in 27% of the surveys. Prophylaxis with antibiotics prior to dental care was recommended by 83%; 77% indicated that it be used for all dental procedures, whether invasive or not. Most respondents (96%) recommended the 1997 American Heart Association endocarditis prevention regimen. A survey of organ transplant centers has provided some information with regard to pre-transplantation dental screening, dental infections, and the use of prophylactic antibiotics. Additional studies are needed in order to accrue more definitive data that will assist with the development of standardized and appropriate pre- and post-transplant dental care protocols.

DEFECTIVE HCV SPECIFIC T CELL RESPONSE IN LIVER TRANSPLANTED RECIPIENTS

O32 Aims: To evaluate HCV specific immune responses in liver transplanted patients chronically HCV infected and to determine the impact of the immunosuppression on HCV specific T cell responses. Methods: A total of 40 patients were studied. The frequency of interferon γ (IFN γ) secreting T cells by ELIspot assay was determined in the blood of 12 patients HCV infected who underwent liver transplantation (more than 12 months after the graft) and in 28 chronically HCV infected non-transplanted patients. Determination of the HCV-specific T cell response was performed prior to the initiation of antiviral therapy. In all cases HCV-specific T cell responses were characterised following antigen-specific stimulation using a total of 728 overlapping peptides spanning the entire HCV genome (15-mers overlapping of 11 amino acids) diluted in 54 pools. Results: The 12 transplanted patients had recurrent HCV infection with elevated transaminases, high HCV RNA titres in serum (60% >500 kU) and signs of fibrosis at the biopsy. In the transplanted patients HCV specific T cell responses were detected only in 1 out of 12 patients (8%) whereas they were detected in 12 out 28 (42%) non-transplanted patients (p<0.05). Conclusions: These results suggest that immunosuppressive therapy in transplanted patients may severely curtail the generation of HCV specific immune response. The lack of HCV specific immune response may be at least in part responsible for the rapid progression of HCV infection in transplanted patients.

HUMAN POLYOMA VIRUS IN KIDNEY TRANSPLANTS. SV40 T-ANTIGEN DEMONSTRATION IN THE URINE

P693 Introduction: Human polyoma virus can cause interstitial nephritis in kidney transplants after reactivation of latent virus in renal epithelium. Currently, there is no exact knowledge about the incidence of polyoma virus infection in transplant patients or about the effect on long term transplant outcome. Diagnosis of polyoma virus disease has been based on transplant histology with cytopathic changes in the tubules associated with focal or diffuse tubulointerstitial inflammation and atrophy, findings similar to chronic allograft nephropathy. Immunohistological staining of kidney biopsies with monoclonal SV40 T-antibody and demonstration of decoy cells in the urine have recently been found useful in the diagnosis. Aims: To develop an immunostaining method of urine cytopreparations using fresh urine samples and staining with the monoclonal SV40 antibody and to compare the findings to demonstration of decoy cells in the urine or to kidney histology. Methods: Routine urine samples from pediatric kidney transplant patients collected either early after transplantation or during later controls, were cytocentrifuged and immunostained with SV40-T-ab. The number of SV40-T-antigen positive epithelial cells was counted and compared to the findings in routine urine cytology and transplant histology. Results: Immunostaining of urine cytology with SV40-T-ab demonstrated clearly the infected epithelial cells and the rate of infection could be estimated by semiquantitative counting. There was strong correlation between the findings in the urine and in the biopsies, but in the urine preparations the number of infected cells was much higher than in the biopsies. The high number of SV40 positive cells in the urine also correlated to the severity of clinical infection and to the state of transplant. Conclusion: Immunostaining of urine cytology with SV40-T-antibody seems to be useful in the diagnosis and follow-up of polyoma virus reactivation disease in transplant patients, especially in children with renal transplants.

The sentinel chicken revisited: the impact of West Nile virus infection on transplant patients.

The sentinel chicken revisited: the impact of West Nile virus infection on transplant patients.

Impaired phagocyte respiratory burst responses to opportunistic fungal pathogens in transplant recipients: in vitro effect of r-metHuG-CSF (Filgrastim).

Phagocyte respiratory burst capacity in response to pathogenic fungi and the in vitro effects of granulocyte colony-stimulating factor (G-CSF) were examined in 15 normal volunteers and 39 transplant recipients (4 autologous and 4 allogeneic bone marrow, 3 heart, 10 liver, 8 lung, and 10 kidney). Chemiluminescence was measured for reaction mixtures of diluted whole blood, opsonized fungi, and luminol, with and without in vitro incubation with r-metHuG-CSF (Filgrastim). Transplant patients exhibited significantly impaired respiratory burst responses to conidia and yeast compared with controls, but this was reversed with Filgrastim. Responses to hyphae were low for both groups, and G-CSF had little or no effect. There was excellent correlation between responses to fungi and responses to opsonized zymosan. In vitro respiratory burst capacity is impaired in transplant recipients. This may predict susceptibility to invasive fungal infections. G-CSF can reverse impaired phagocyte function and is of potential benefit in the prevention and/or treatment of fungal infection in transplant patients.

The Immune Modulator FTY720 Targets Sphingosine 1-Phosphate Receptors

Immunosuppressant drugs such as cyclosporin have allowed widespread organ transplantation, but their utility remains limited by toxicities, and they are ineffective in chronic management of autoimmune diseases such as multiple sclerosis. In contrast, the immune modulating drug FTY720 is efficacious in a variety of transplant and autoimmune models without inducing a generalized immunosuppressed state and is effective in human kidney transplantation. FTY720 elicits a lymphopenia resulting from a reversible redistribution of lymphocytes from circulation to secondary lymphoid tissues by unknown mechanisms. Using FTY720 and several analogs, we show now that FTY720 is phosphorylated by sphingosine kinase; the phosphorylated compound is a potent agonist at four sphingosine 1-phosphate receptors and represents the therapeutic principle in a rodent model of multiple sclerosis. Our results suggest that FTY720, after phosphorylation, acts through sphingosine 1-phosphate signaling pathways to modulate chemotactic responses and lymphocyte trafficking.

Cytomegalovirus Infection

Cytomegalovirus Infection

Low cell dosage of lymphoblastoid human cell lines EBV(+) is associated to chronic hepatitis in a minority of inoculated Nu/Nu mice.

It has been suggested that an atypical course of primary infection by EBV and the reactivation of EBV infection in transplanted patients may induce hepatitis. We explored the possibility to dissect the infectious activity from the ability to promote B lymphocyte proliferation in vivo by injecting in nu/nu mice a low number (2 x 10(6)-0.05 x 10(6)) of cells from CE a normal human bone marrow-derived B cell line. This line carries an endogenous EBV in episomal and linear forms. Twenty nu/nu mice were inoculated subcutaneously with the B cell line CE and a matched group with the cell line RAG obtained by EBV in vitro infection of normal human peripheral blood. The mice injected with the CE line did not develop a lymphoproliferative disease, but 5 of them displayed typical histopathological lesions of chronic hepatitis without involvement of other organs. Similar results were obtained in 2 out of 20 animals in the RAG group. A close association between liver lesions and a previous EBV infection, by putative circulating B lymphoblastoid cells releasing their EBV, was established by PCR and by in situ hybridization with BamHI "W" DNA probe. This latter probe detected the presence of about 15% of positive cells only in affected livers. In addition, the rare detection in some hepatocytes of "A" type Cowdry bodies would suggest the occurrence of continuous EBV replication although at a very low level. These data show that we succeeded in dissecting the infectious from the proliferative activity of the endogenous EBV carrier CE cell line. This provides in addition a promising model for chronic EBV-associated hepatitis.

Epstein-Barr virus infection in paediatric liver transplant recipients: detection of the virus in post-transplant tonsillectomy specimens

Aims—Post-transplant lymphoproliferative disease (PTLD) is an important and serious complication in transplant patients. Recent studies have suggested that quantitative assessment of Epstein-Barr virus (EBV) infection in transplant patients might help...