Isolation of viruses from stools in stem cell transplant recipients: a prospective surveillance study

Broad Virus Detection and Variant Discovery in Fecal Samples of Hematopoietic Transplant Recipients Using Targeted Sequence Capture Metagenomics

Pediatric allogeneic hematopoietic stem cell transplantation (HSCT) patients often suffer from gastro-intestinal (GI) disease caused by viruses, Graft-versus-Host Disease (GVHD) or a combination of the two. Currently, the GI eukaryotic virome of HSCT recipients remains relatively understudied, which complicates the understanding of its role in GVHD pathogenicity. As decisions regarding immunosuppressive therapy in the treatment of virus infection or GVHD, respectively, can be completely contradicting, it is crucial to better understand the prevalence and relevance of viruses in the GI tract in the HSCT setting. A real time PCR panel for a set of specific viruses widely used to diagnose the most common causes of GI viral gastroenteritis is possibly insufficient to grasp the full extent of viruses present. Therefore, we applied the targeted sequence capture method ViroCap to residual fecal samples of 11 pediatric allogeneic HSCT recipients with GI symptoms and a suspicion of GVHD, to enrich for nucleic acids of viruses that are known to infect vertebrate hosts. After enrichment, NGS was applied to broadly detect viral sequences. Using ViroCap, we were able to detect viruses such as norovirus and adenovirus (ADV), that had been previously detected using clinical diagnostic PCR on the same sample. In addition, multiple, some of which clinically relevant viruses were detected, including ADV, human rhinovirus (HRV) and BK polyomavirus (BKV). Interestingly, in samples in which specific PCR testing for regular viral GI pathogens did not result in a diagnosis, the ViroCap pipeline led to the detection of viral sequences of human herpesvirus (HHV)-7, BKV, HRV, KI polyomavirus and astrovirus. The latter was an only recently described variant and showed extensive sequence mismatches with the applied real time PCR primers and would therefore not have been detected if tested. Our results indicate that target enrichment of viral nucleic acids through ViroCap leads to sensitive and broad possibly clinically relevant virus detection, including the detection of newer variants in clinical HSCT recipient samples. As such, ViroCap could be a useful detection tool clinically, but also in studying the associations between viral presence and GVHD.

A survey on incidence and management of adenovirus infection after allogeneic HSCT

To determine the current practices on the management of Adenovirus (ADV) infection after allogenic stem cell transplantation, a survey was undertook among EBMT centres. The response rate was 20% (91/446): 46% were adult, 44% were paediatric and 10% were mixed centres, respectively. The overall incidence of ADV infection was 7.1%: 4.1% in adult, 15.4% in paediatric, and 3.6% in mixed population. The determination of ADV-DNA in biological samples was used in 96% of centres; 58% of them monitored asymptomatic patients with a frequency of twice a week in 9%, once a week in 45%, every two weeks in 4% of centres. The treatment of ADV infection was mainly based on the administration of cidofovir (87%), being the schedule of 5 mg/kg/week with probenecid the most used, and the reduction of immunosuppression (84%). The threshold of ADV-DNAemia to start cidofovir in high-risk patients was most frequently >1000 copies/ml. Innovative treatments, such as brincidofovir and adoptive ADV-cytotoxic-T-lymphocytes, were used in 27% and 20% of centres, respectively. Almost all responding centres consider ADV infection serious enough to deserve testing asymptomatic or symptomatic patients. Cidofovir and reduction of immunosuppression represent the main therapeutic options but one fourth of responding centres experimented novel therapies.

Detection of human cytomegalovirus (CMV) DNA in feces has limited value in predicting CMV enteritis in patients with intestinal graft-versus-host disease after allogeneic stem cell transplantation

BACKGROUND

Cytomegalovirus (CMV) enteritis after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is difficult to diagnose. We aimed to evaluate the sensitivity and specificity of the detection of CMV DNA in feces for predicting CMV enteritis.

METHODS

HSCT patients with intestinal graft-versus-host disease (GVHD) were enrolled if they met the following criteria: (i) underwent a colonoscopy and (ii) peripheral blood and feces specimens were available for CMV DNA detection within 24 h of colonoscopy. The colonoscopy histology was used as the gold standard for diagnosing CMV enteritis.

RESULTS

Fifty-six patients underwent 58 colonoscopy examinations, and 7 were diagnosed as having CMV enteritis. Within 24 h of colonoscopy, 9 patients had detectable CMV in the feces and 19 patients had detectable CMV in the plasma, respectively. In the 7 patients with CMV enteritis, only 2 had detectable CMV in the stool, resulting in a sensitivity of 28.6%. In the 51 patients without CMV enteritis, 44 had no detectable CMV in the stool, with a specificity of 86.3%.

CONCLUSION

We concluded that CMV detection in the feces was not a good predictor of CMV enteritis in patients with intestinal GVHD after allo-HSCT.

Impact of adenoviral stool load on adenoviremia in pediatric hematopoietic stem cell transplant recipients

BACKGROUND

Adenoviremia adversely affects prognosis in the post-hematopoietic stem cell transplant setting.

METHODS

We sought to determine retrospectively the cutoff load of adenovirus in the stool as a predictor of adenoviremia, in children who underwent an allogeneic hematopoietic stem cell transplant. The prevalence of sapovirus, norovirus and astrovirus in the stool was also studied.

RESULTS

The study cohort consisted of 117 patients, of which 71 (60%) had diarrhea. Adenovirus was detected in the stool in 39 of 71 (55%) patients. Age ≤10 years (P = 0.05; odds ratio: 2.57; 95% confidence interval: 0.98-6.75) and male sex (P = 0.04; odds ratio: 2.67; 95% confidence interval: 1.02-6.99) increased risk for detection of adenovirus in stool on univariate analysis. Coinfections with enteric pathogens were infrequent. Viral load >10 copies/g stool predicted adenoviremia with a sensitivity and specificity of 82%. Sapovirus, norovirus and astrovirus were detected in 3, 4 and 1 patient, respectively.

CONCLUSIONS

Quantitative detection of adenovirus in stool may have implications for preemptive therapy. Testing for other enteric viruses may have implications for infection control.

The burden of norovirus gastroenteritis: an important foodborne and healthcare-related infection

Human norovirus (NoV) is now recognized as one of the most important causative agents of gastroenteritis in all age groups worldwide. During the course of NoV infection, symptoms are usually mild and disappear within 48 h after onset. The incidence of NoV infection is high, with hundreds of cases per 10 000 of the population, although the number of infections is still underestimated. Epidemiological surveys conducted in Europe and North America have shown that NoV infections constitute a major disease burden, especially for young children and the elderly, in whom NoV infection leads to high rates of hospitalization and mortality. NoV infections are also of concern in hospitals, where viral infections can be persistent in immunocompromised patients. Although the cost of NoV infection in the hospital community has not yet been clearly established, it appears that NoV infections could cost hundreds of thousands of euros in terms of unit closure, and NoV-related sickness in patients and health workers. Besides their clinical burden, NoVs, as foodborne pathogens, also cause to millions of dollars of losses for the healthcare system and the food industry. Recent estimates in the USA showed that, annually, NoV illness cost $2 billion and led to a loss of approximately 5000 quality-adjusted life-years, making NoV one of the top five pathogens causing enteric illnesses. The highest cost among 14 foodborne pathogens is also attributed to human NoV in The Netherlands. This accumulation of evidence underlines the enormous impact of NoV on populations.

Diagnostic value of quantitative PCR for adenovirus detection in stool samples as compared with antigen detection and cell culture in haematopoietic stem cell transplant recipients

Adenovirus (AdV) infections constitute a significant cause of morbidity and mortality during haematopoietic stem cell transplantation. Recent guidelines recommend repeated screening for AdV in whole blood (WB), with quantitative PCR (qPCR) as the reference standard. Despite pre-emptive antiviral treatment based on qPCR in WB, the mortality rate after disseminated AdV infection remains very high. The aim of our study was to advance early screening for AdV, using a standardized method, so as to enable the earlier initiation of antiviral treatment or adoptive immunotherapy. The diagnostic value of AdV DNA quantification in stool samples was investigated retrospectively and compared with antigen detection and cell culture in 21 patients with AdV infection, from 182 patients followed in the Transplant Unit of Nancy University Hospital Centre, including 18 patients with systemic infection. In 16/18 patients with positive AdV viraemia, AdV DNA was present in stool samples earlier than in WB (median, 42 days; range, 3-199 days), whereas both antigen detection and cell culture were still negative for 11/18 patients with systemic AdV infection. The course of AdV viral loads in stool samples was predictive of adenoviraemia (sensitivity, 89%). Very late and lethal AdV infections were observed in cord blood transplant recipients, and would have been detected much earlier with the use of qPCR on stool samples. This study confirmed that quantification of AdV in stool samples by qPCR is beneficial for the management of transplant recipients, with or without antigen detection.

Norovirus: a possible cause of pneumatosis intestinalis

OBJECTIVE

Pneumatosis intestinalis (PI) in children is associated with immunosuppression, mucosal disruption from trauma, obstructive pulmonary disease, congenital heart disease, and gastrointestinal infections. Our study is the first report of norovirus infection-associated PI.

PATIENTS AND METHODS

A retrospective review was performed in pediatric patients (older than 30 days) with PI from March 2005 to April 2009. Since December 2008, in addition to routine stool examinations, reverse-transcriptase polymerase chain reaction testing for calicivirus (norovirus and sapovirus), adenovirus, astrovirus, and enterovirus has been performed.

RESULTS

Twenty-seven patients with PI were identified. The median age was 1.4 (range 0.2-14.8 years). Seventeen patients (63.0%) were immunocompromised hosts. Pathogens were identified in 5 immunocompromised patients (5/27 and 5/8 since December 2008). Of note, norovirus was identified in 4 patients (80%, 4/5) during the cold weather season. The genotype of noroviruses in these patients was GII-4. Among 27 patients with PI, 10 patients (37.0%) developed PI in the spring and 11 (40.7%) in the winter. Twenty-four patients survived (88.9%, 24/27). None of the patients with norovirus or rotavirus infection died.

CONCLUSIONS

Our data suggest that norovirus infection may contribute to the development of PI in immunocompromised hosts.

Comparison of in-house real-time quantitative PCR to the Adenovirus R-Gene kit for determination of adenovirus load in clinical samples

In the context of hematopoietic stem cell transplantation, adenovirus infections are associated with relevant mortality and morbidity. Detection of adenovirus DNA by quantitative PCR is the "gold standard" for these patients. A total of 150 samples, namely, 78 whole-blood, 22 cerebrospinal fluid, 24 digestive biopsy, and 26 stool samples, from 29 patients, including 24 hematopoietic stem cell transplant recipients, were tested for the detection of adenovirus using an in-house real-time quantitative PCR assay (A. Heim, C. Ebnet, G. Harste, and P. Pring-Akerblom, J. Med. Virol. 70:228-239, 2003) and the commercially available Adenovirus R-Gene kit. Adenovirus DNA was automatically isolated from whole-blood samples (Magna Pure LC system; Roche) or was manually extracted from other specimens (QIAamp; Qiagen) using the appropriate kit. The intra- and interassay reproducibilities and sensitivities were evaluated with cell culture supernatant dilutions. Of the 150 samples tested, 86 were found to be positive and 55 were found to be negative using both techniques. Nine (6%) discordant results were obtained. In most cases, discrepant results concerned samples with low viral loads. Quantitative results for all concordant positive samples were analyzed using the Spearman correlation test. A good correlation between the results of the in-house assay and those of the kit assay was obtained (r = 0.95; P < 0.001). Regarding the threshold cycle value for internal control spiked samples, none of the 150 samples tested contained a PCR inhibitor. In conclusion, a relevant correlation of results between the in-house assay and the kit assay, as well as the high-quality reproducibility and sensitivity of the kit assay, warranted its use for follow-up of hematopoietic stem cell transplantation recipients.

A clinical algorithm identifies high risk pediatric oncology and bone marrow transplant patients likely to benefit from treatment of adenoviral infection

BACKGROUND

Adenoviral infections cause morbidity and mortality in blood and marrow transplantation and pediatric oncology patients. Cidofovir is active against adenovirus, but must be used judiciously because of its nephrotoxicity and unclear indications. Therefore, before introducing cidofovir use during an adenoviral outbreak, we developed a clinical algorithm to distinguish low risk patients from those who merited cidofovir therapy because of significant adenoviral disease and high risk for death.

OBJECTIVE

This study was conducted to determine whether the algorithm accurately predicted severe adenovirus disease and whether selective cidofovir treatment was beneficial.

STUDY DESIGN

A retrospective analysis of a pediatric oncology/blood and marrow transplantation cohort prealgorithm and postalgorithm implementation was performed.

RESULTS

Twenty patients with adenovirus infection were identified (14 high risk and 6 low risk). All low-risk patients cleared their infections without treatment. Before algorithm implementation, all untreated high-risk patients died, 4 out of 5 (80%), from adenoviral infection. In contrast, cidofovir reduced adenovirus-related mortality in the high-risk group postalgorithm implementation (9 patients treated, 1 patient died; RR 0.14, P<0.05) and all treated high-risk patients cleared their virus.

CONCLUSIONS

The clinical algorithm accurately identified patients at high risk for severe fatal adenoviral disease who would benefit from selective use of cidofovir.

Adenovirus infection after allogeneic stem cell transplantation

Adenovirus infection after allogeneic hematopoietic stem cell transplantation (HSCT) is an emerging pathogen causing relevant morbidity and mortality, with preponderance in children. During the last years, basic research on the biology of the virus and host immune response ameliorated the diagnostic, surveillance, and therapeutic strategies. Risk factors for infection commonly have an impact on T-cell reconstitution, such as T-cell depleted graft, unrelated or HLA-mismatched donor transplantation, and GvHD. Weekly surveillance by PCR in stool and blood till day 100 or longer post-HSCT and pre-emptive therapy with cidofovir are the mainstay of the current approach to adenoviral infections post-HSCT. Since a sufficient host T-cell response is essential to clear the virus, diagnostic procedures for detection of virus-specific T-cells have recently been developed to assess the risk of the infection. Furthermore, adoptive immunotherapy is a new treatment option for patients with absent specific T-cell response and present systemic adenoviral infection.

Wireless capsule endoscopy for diagnosis of acute intestinal graft-versus-host disease

BACKGROUND

The small intestine is the most common location of intestinal graft-versus-host disease (GVHD). EGD with duodenal biopsies yields the highest diagnostic sensitivity, but the jejunum and ileum are not accessible by regular endoscopy. In contrast, wireless capsule endoscopy (WCE) is a noninvasive imaging procedure offering complete evaluation of the small intestine.

OBJECTIVE

The objective was to compare the diagnostic value of EGD, including biopsies, with the results of WCE in patients with acute intestinal symptoms who received allogeneic blood stem cell transplantation and to analyze the appearance and distribution of acute intestinal GVHD lesions in these patients.

DESIGN

An investigator-blinded, single-center prospective study.

PATIENTS

Patients with acute intestinal symptoms after allogeneic stem cell transplantation underwent both EGD and WCE within 24 hours. Clinical data were recorded during 2 months of follow-up.

RESULTS

Fourteen consecutive patients with clinical symptoms of acute intestinal GVHD were recruited. In 1 patient, the capsule remained in the stomach and was removed endoscopically. In 7 of 13 patients who could be evaluated, acute intestinal GVHD was diagnosed by EGD with biopsies, but 3 of these would have been missed by EGD alone. In all 7 patients with histologically confirmed acute intestinal GVHD, WCE revealed typical signs of GVHD. Lesions were scattered throughout the small intestine, but were most accentuated in the ileum.

LIMITATIONS

This study had a small number of patients.

CONCLUSIONS

WCE, which is less invasive than EGD with biopsies, showed a comparable sensitivity and a high negative predictive value for diagnosing acute intestinal GVHD. It may be helpful to avoid repeated endoscopic procedures in patients who have undergone stem cell transplantation.

Norovirus outbreak in a pediatric oncology unit

OBJECTIVE

Norovirus (NV) is an etiologic agent of outstanding importance that can cause severe epidemic gastroenteritis in day-care centers, schools, nursing homes, and hospitals. Therefore NV requires foremost attention as a pathogen responsible for epidemics of gastroenteritis in immunocompromised inpatients. In this study, a NV outbreak in a pediatric oncology unit is described and the consequences for this high-risk population are discussed.

MATERIAL AND METHODS

Stool and vomitus samples from 11 patients were tested for NV and other relevant viruses during the outbreak by reverse transcriptase-polymerase chain reaction (RT-PCR) and/or enzyme-linked immunosorbent assay (ELISA) (whenever an appropriate ELISA was available). Norwalk virus PCR amplifications were sequenced and phylogenetic analysis was performed.

RESULTS

The index patient and the chain of infection were identified. Follow-up investigation surprisingly demonstrated viral shedding for a maximum of 140 days (median 23 days). Three patients experienced severe or life-threatening symptoms, probably related to NV infection.

CONCLUSIONS

In the event of an outbreak of gastroenteritis (involving two or more symptomatic patients) in a pediatric oncology unit, the search for NV in stool or vomitus specimens should be initiated in good time. As long as the data are limited regarding whether a detectable viral antigen or RNA in stools represents an infectious virus, patients have to be isolated as long as the diagnostic assays remain positive. During the acute phase of the illness, health-care workers should wear masks in addition to practicing meticulous hand hygiene with a disinfectant of proven activity against NV. Pediatric oncology patients must be closely monitored during follow-up investigations as they may shed the virus for months. There is some evidence from the outbreak described here that those patients face a greater risk of severe NV-related complications.

Cytomegalovirus disease in the era of highly active antiretroviral therapy (HAART)

Cytomegalovirus (CMV) infection was one of the most important opportunistic infections in HIV-infected patients before the introduction of highly active antiretroviral therapy (HAART), i.e. the combination of at least three antiretroviral drugs of different classes. Thereafter, life expectancy and quality of life increased dramatically with the persistent suppression of HIV viremia and a significant reduction in incidence of CMV disease. Nevertheless, evidence for a multitude of direct and indirect effects of CMV on HIV progression is accumulating. Even in the era of HAART, a considerable number of HIV-infected patients have a CD4 cell count below <100 mm(-3), which involves a high risk for CMV disease. The focus of the present review is on interpretation of test results, their predictive value for CMV disease, and guidance for the rational use of diagnostic assays in HIV-infected patients. Identification of patients at immediate risk for CMV disease may be accomplished by detection of CMV-DNA in leucocytes or plasma. Evidence is growing that CMV genotypes may be also relevant for the risk of CMV disease. Diagnosis of CMV disease requires in most instances demonstration of virus in biopsy specimen from the affected organ because presence of CMV in blood may not be causally related to symptoms observed. Clinical symptoms and patient characteristics are essential in the interpretation of laboratory test results and may guide the rational collection of clinical specimen and use of laboratory assays. As a consequence, a reliable diagnosis of CMV disease and early identification of patients at high risk for CMV disease requires an integrated interpretation of clinical and virological information.

GI complications in pediatric patients post-BMT

This retrospective study comprehensively examined hepatic and gastrointestinal complications post-bone marrow transplant (BMT) in a heterogeneous group of 132 pediatric patients that underwent 142 transplants. Hyperbilirubinemia occurred in 28% of this population with clinically evident jaundice in 16%. Acute graft-versus-host disease (GVHD) occurred in 46% of the population, with liver involvement in 39% and intestinal involvement in 60% of those with acute GVHD. Veno-occlusive disease (VOD) occurred in 18% of the population. A greater increase in hepatic transaminases was noted in GVHD and VOD than nonspecific liver injury. Serum bilirubin may help to differentiate between VOD and hepatic GVHD. Biliary sludging occurred in 20% of patients and was associated with increased morbidity. Common post transplant gastrointestinal complications included mucositis in 90%, vomiting in 85% and abdominal pain in 71%. TPN support post transplant was required in 91%. Diarrhea occurred in 67% with the most common identified etiologies reported as GVHD (27%), viral (6%), Clostridium difficile (8%) infections and unknown (28%). Typhilitis developed in 3.5%. Melena or hematochezia occurred in 11 patients (8%). However, gastrointestinal bleeding was disproportionately represented in intensive care unit admissions (5/27) and 100 day mortality (5/21). Gastrointestinal and hepatic complications represent a major cause of morbidity and mortality in pediatric BMT recipients.

Application of a molecular panel to demonstrate enterotropic virus shedding by healthy and human immunodeficiency virus-infected patients

We used a molecular panel, targeting seven enteric viruses, to explore the advantage of using molecular methods to establish the etiology of enteric diseases and to evaluate the prevalence of enteric viruses in asymptomatic human immunodeficiency virus-infected patients. This approach favors rapidity and sensitivity of laboratory diagnosis of viral enteric syndromes.

Adenovirus infections in stem cell transplant recipients: recent developments in understanding of pathogenesis, diagnosis and management

Adenovirus is increasingly recognized as an important pathogen in stem cell transplant recipients, reflecting increased awareness about the virus, together with changes in transplant practice such as the performance of more high-risk transplants, and improvements in diagnostic methods. In retrospective studies, the reported incidence of adenovirus infections ranged between 4-20% with a similar variation in the proportion of patients developing invasive disease. In contrast, the incidence of adenovirus infection varies between 20-30% in recent prospective studies on T-cell depleted or mismatched allografts and about 30-40% of these patients develop invasive disease. These prospective studies have established a relationship between the risk of invasive adenovirus disease and a number of factors such as the extent of T-cell depletion, the intensity of immunosuppressive therapy and the kinetics of lymphocyte recovery post-transplant. Polymerase chain reaction (PCR) assays to detect adenovirus DNA in peripheral blood have shown a strong correlation between viremia and the risk of disseminated adenovirus disease. These developments have led to the possibility of a preemptive antiviral treatment strategy for asymptomatic adenovirus infections. In addition, a better understanding of the interactions between adenovirus and host immune system in the post-transplant setting might enable development of effective immunotherapeutic strategies against adenovirus infections.

Impact of Small Bowel Exploration Using Video-Capsule Endoscopy in the Management of Acute Gastrointestinal Graft-versus-Host Disease

BACKGROUND

The purpose of this study was to evaluate the impact of the global diagnostic approach on the outcome of patients suspected of having acute (a) gastrointestinal (GI) graft-versus-host disease (GVHD).

METHODS

Ten consecutive patients with suspected aGI-GVHD were prospectively explored with an exhaustive approach including video-capsule endoscopy (VCE). Images observed with VCE were compared with results obtained with other GI investigations including duodenal biopsies. RESULTS.: Five patients had a normal VCE examination: four were successfully treated symptomatically, but one died as a result of toxoplasmosis. VCE disclosed aGI-GVHD lesions in all five remaining patients, and two of the five were considered normal by upper GI endoscopy. All of these patients experienced improvement in their GI symptoms within 2 weeks of adjustments to their immunosuppressive treatment.

CONCLUSIONS

This approach has enhanced the authors' ability to adapt immunosuppressive treatments in patients suffering from suspected aGI-GVHD. Further investigation of the apparently high negative predictive value of VCE will be of great interest, particularly with a view to avoiding unnecessary immunosuppressive treatment.

Human caliciviruses and pediatric gastroenteritis

Surveillance using molecular diagnostic methods developed in the past decade shows that human caliciviruses, particularly the Noroviruses, are the most important cause of pediatric acute gastroenteritis, next to rotavirus. Noroviruses also cause severe gastroenteritis in children, requiring hospitalization. The Sapovirus, a morphologically and genetically distinct genus of calicivirus, cause mainly milder endemic pediatric gastroenteritis. Noroviruses and Sapoviruses are genetically and antigenetically diverse, and multiple genetic types cocirculate in the same community. Human caliciviruses still cannot be cultivated in cell culture or in an animal model. Significant progress has been made in the past decade in the classification, diagnosis, and vaccine development, as well as in the recent discovery of Norovirus recognizing human histoblood group antigens as receptors. Major developments in this field are expected to occur in the near future.

Enterovirus infections following T-cell depleted allogeneic transplants in adults

Anecdotally, enteroviruses have been reported to cause serious complications post BMT, but the exact impact of these viruses in the post transplant period has not been reported. We prospectively evaluated stool, urine and throat samples for enteroviruses by viral culture together with relevant body fluids by RT-PCR in 64 allograft recipients receiving grafts T-cell depleted by Campath-1H, following both conventional and reduced-intensity conditioning. Seven patients (10.4%) developed nine episodes of enterovirus infections at a median of 146 days post transplant. Four episodes were associated with symptomatic illnesses, which could be attributable to enteroviruses. There was no mortality directly related to enteroviruses. There was no correlation between dose and mode of Campath-1H use, lymphocyte recovery, IgG and IgA levels and enterovirus isolation. Although enteroviruses tended to be more frequent in TBI-based conventional conditioning recipients, the only significant risk factor for enterovirus infection was unrelated donor graft. The low incidence of the severe enterovirus infections could have been related to a low lymphocyte count in this cohort in the absence of GVHD, particularly CD4+ count, which has been implicated in tissue damage in experimental animals. Further studies are needed to define its impact in different allograft settings.

Hemorrhagic cystitis after allogeneic bone marrow transplantation in children: clinical characteristics and outcome

Hemorrhagic cystitis (HC) is a well-documented adverse event experienced by patients undergoing hematopoietic stem cell transplantation. When severe, HC causes significant morbidity, leads to renal complications, prolongs hospitalization, increases health-care costs, and occasionally contributes to death. We retrospectively studied the medical records of 245 children undergoing an initial allogeneic bone marrow transplantation for malignant disease at St. Jude Children's Research Hospital between 1992 and 1999 to describe the clinical course of HC in all patients and to identify the risk factors for HC in this cohort. Conditioning regimens included cyclophosphamide, cytarabine, and total body irradiation. Grafts from unrelated or mismatched related donors were depleted of T lymphocytes, whereas matched sibling grafts were unmanipulated. All patients received cyclosporine as prophylaxis for graft-versus-host disease. Recipients of grafts from matched siblings also received pentoxifylline or short-course methotrexate. Severe HC developed in 27 patients (11.0%). The median duration of HC was 73 days (range, 5-619 days); 12 patients had ongoing HC at the time of death. In univariate analyses, patients were at increased risk of severe HC if they were male (P =.021) or had received T cell-depleted grafts (P =.017), grafts from unrelated donors (P =.021), a lower total nucleated cell dose (P =.032), or antithymocyte globulin (P =.0446). Multiple regression analysis revealed male sex (beta =.97; P =.027) and unrelated donor graft recipients (beta =.83; P =.039) to be significant factors.

Adenovirus infection in hematopoietic stem cell transplantation: effect of ganciclovir and impact on survival

Adenoviruses (ADV) are emerging as important causes of morbidity and mortality in patients undergoing hematopoietic stem cell transplantation (HSCT). In mainly non-T-cell depleted HSCT recipients, we analyzed the incidence of ADV infection, risk factors for infection, the effect of ganciclovir administered for prevention of cytomegalovirus (CMV), and the impact of ADV infection on survival. The overall incidence of ADV, irrespective of the method of detection, was 8.5% (450/5233) and 12.3% (43/348) after the first or second allogeneic HSCT, and 6.3% (78/1219) and 6.5% (5/77) after the first or second autologous HSCT, respectively. The most frequent sites of infection and disease were stool and gastrointestinal tract, respectively. Statistically significant risk factors associated with ADV infections among allogeneic recipients included younger age, grade II to IV graft-versus-host disease, year of transplantation, and a second allogeneic HSCT. Furthermore, allogeneic patients seronegative for CMV at transplantation and seropositive allogeneic patients who did not receive ganciclovir, either at engraftment or as pre-emptive therapy on CMV reactivation, were at higher risk of developing ADV infections compared with seropositive patients who received ganciclovir (odds ratio=1.8, 95% confidence interval (CI) 1.2 to 2.8, P=.005 and odds ratio=3.4, 95% CI 2.1 to 5.55, P<.0001, respectively). The hazard of overall mortality was higher in patients who contracted ADV compared with those who did not (hazard ratio 1.5, 95% CI 1.3 to 1.7, P<.0001). This study shows that ADV infections are associated with poor transplantation outcome in T-cell repleted HSCT recipients. Ganciclovir, given for CMV prevention, may have a protective effect. Controlled treatment and prevention studies are warranted.

Infections during mobilizing chemotherapy and following autologous stem cell transplantation

Autologous peripheral blood stem cells (PBSC), for transplantation following high-dose chemotherapy, are collected using regimens containing cytokines with or without chemotherapy. The added period of neutropenia prior to stem cell transplantation (SCT) in patients receiving chemotherapy mobilization may increase the risk of infections following transplantation. We studied the incidence of culture-positive infections in 107 consecutive patients who were divided into three groups, according to whether they experienced extended neutropenia during chemotherapy for stem cell mobilization as well as post autotransplant. All the patients received antibiotic prophylaxis and hematopoietic growth factors during neutropenia. The total duration of pre-transplant neutropenia differed among the three mobilization schemes (growth factors alone; one cycle; or two cycles of chemotherapy plus growth factor for mobilization) at 0, 6 and 18 days, respectively (median). However the post-autograft time to myeloid engraftment was similar at 10 days (median). The incidence of culture-proven infections in all three groups was similar. Using fluconazole for yeast prophylaxis, 40% patients developed gastrointestinal colonization with yeast, and the majority of speciated isolates were Candida glabrata. Bacteremia developed in 22% and 9% of patients with S. epidermidis and Gram-negative organisms, respectively, while 11% developed C. difficile-associated diarrhea. In conclusion, treatment using none, one or two cycles of mobilizing chemotherapy pre-transplant does not influence the overall incidence of infections among autologous SCT recipients. However, although post-transplant neutropenia is brief, infections remain a significant cause of morbidity.

Viral causes of diarrhea

Viruses are important causes of diarrhea. In healthy adults, the main clinical manifestation is acute, self-limited gastroenteritis. Advances in molecular diagnostics have shown that epidemics of acute gastroenteritis most frequently are due to caliciviruses spread through contaminated food or through person-to-person contact. Application of similar technology is needed to make a definitive statement about the role of such candidate viruses as rotavirus, astrovirus, and adenovirus as the cause of nonepidemic acute gastroenteritis in adults. Rarely a previously healthy adult gets acute CMV colitis. CMV and EBV mainly cause diarrhea in immunocompromised patients, however. Advances in prophylaxis and treatment have reduced the frequency and severity of these diseases. Acute infantile gastroenteritis is caused by rotavirus, calcivirus, astrovirus, and adenovirus. These viral diseases of the gut are seen by the physician as routine and rare clinical problems.

Gastrointestinal infections in the immunocompromised host

Gastrointestinal disease is a significant cause of morbidity and mortality in the immunocompromised patient. This article focuses on the infectious gastrointestinal complications associated with the treatment of malignant disease and with solid organ transplantation but not HIV. Gastrointestinal defenses and the various mechanisms by which they are impaired are reviewed. The major pathogens and malignancies of this patient population and an approach to their diagnosis, treatment, and prevention are discussed.