A Case of Adenovirus Viremia in a Pediatric Liver Transplant Recipient With Neutropenia and Lymphopenia: Who and When Should We Treat?

Human adenovirus (HAdV) is one of the most feared infections among immunocompromised patients. In particular, in liver transplant patients, HAdV has been implicated in acute liver failure with resultant mortality. The development of current molecular techniques and surveillance testing protocols have provided tools for early detection of HAdV infection, prior to or at the early onset of HAdV disease. Although reduction in immune suppression is the mainstay of therapy, many researchers have also advocated for early administration of antiviral therapy. In multiple reports, cidofovir treatment has been associated with declines in HAdV viral loads or clinical improvement in solid organ and bone marrow transplant recipients. However, there have also been case reports that raise questions about the effectiveness of antiviral therapy in controlling systemic HAdV disease. We report a case of a 26-month-old male recipient of a liver transplantation for hepatoblastoma who developed adenoviremia with an associated hepatitis and gastroenteritis. He recovered with reduced immune suppression but without antiviral therapy, thus avoiding potential toxicities associated with cidofovir therapy. This case a contrast to previous reports, and it highlights the ambiguity regarding which patients should receive HAdV-specific antiviral therapy. Additional knowledge regarding specific pediatric host factors and HAdV factors that predict poor outcomes are needed. Such information would allow clinicians to better stratify patients by risk at the time of adenoviremia detection so that low-risk patients are not unnecessarily exposed to medications with potential toxicities.

Multicenter comparison of different real-time PCR assays for quantitative detection of Epstein-Barr virus.

Quantification of Epstein-Barr virus (EBV) in peripheral blood is important for the diagnosis and management of serious EBV diseases, including posttransplant lymphoproliferative disorder. A variety of PCR-based methods are currently in use; however, there is little information on their comparability. This study assessed the relative performance of different quantitative assays. A multicenter comparative study was performed at eight sites using three panels consisting of serial dilutions of quantified EBV DNA and extracts from a total of 19 whole-blood specimens. Samples were distributed and tested blindly. Instrumentation, probe chemistries, amplification targets, and other test-related aspects varied considerably between laboratories. Each laboratory's calibration curve indicated strong evidence of a consistent log-linear relationship between viral load and cycle threshold, suggesting that intralaboratory tracking of a given patient would yield similar relative quantitative trends among the participating test sites. There was strong concordance among laboratories with respect to qualitative test results; however, marked quantitative discordance was seen. For most samples, the across-laboratory interquartile range of the reported viral load (in copies/microl) was roughly 0.6 log-units, and for one sample the overall range was approximately 4.2 log-units. While intralaboratory tracking of patients may yield similar results, these data indicate a need for caution when attempting to compare clinical results obtained at different institutions and suggest the potential value to be gained by more standardized testing methodology.

Biochemical characterization of a virus isolate, recovered from a patient with herpes keratitis, that was clinically resistant to acyclovir.

In vitro susceptibility assays of herpes simplex virus (HSV) do not necessarily correlate with treatment outcome. An HSV type 1 (HSV-1) isolate, N4, recovered from a patient who presented with herpes keratitis with localized immunosuppression, was characterized for susceptibility. Although the 50% inhibitory concentration (IC(50)) for this isolate was less than the accepted breakpoint for defining resistance to acyclovir (>2.0 microg/mL), the following lines of evidence suggest that the isolate was acyclovir resistant: (1) the clinical history confirmed that the infection was nonresponsive to acyclovir; (2) the in vitro susceptibility was similar to that of a thymidine kinase (TK)-negative, acyclovir-resistant virus SLU360; (3) the IC(50) of acyclovir was more than 10 times the IC(50) for an acyclovir-susceptible control strain; (4) plaque-purified clonal isolates were resistant to acyclovir (IC(50)s, >2.0 microg/mL); and (5) biochemical studies indicated that the HSV-1 N4 TK was partially impaired for acyclovir phosphorylation. Although residue changes were found in both the viral tk and pol coding regions of HSV-1 N4, characterization of a recombinant virus expressing the HSV-1 N4 polymerase suggested that the TK and Pol together conferred the acyclovir-resistance phenotype.

Metachronous Epstein-Barr virus-related smooth muscle tumors in a child after heart transplantation: case report and review of the literature.

Soft tissue tumors are uncommon manifestations of Epstein-Barr virus (EBV) infection in patients who have had transplants. The authors report 2 metachronous EBV-containing smooth muscle tumors in a child who had a heart transplant, and review the literature on posttransplant soft tissue tumors.

Post-transplant lymphoproliferative disease in children.

Epstein-Barr virus (EBV)-driven post-transplant lymphoproliferative disease (PTLD) is an important cause of morbidity and mortality following transplantation, and it occurs more frequently in children than in adults. Of 22 (5%) children at our institution who developed tissue-proven PTLD 1-60 months (mean 16.5 months) following organ transplant, 11 died: nine of these 22 patients developed PTLD between 1989 and 1993, and seven (78%) died; the remaining 13 developed PTLD between 1994 and 1998, and four (31%) died (p = 0.08). All nine patients who developed PTLD < 6 months after transplant died, but 11 of 13 patients who manifested disease > or = 6 months after transplant survived (p = 0.0002). Ten of 11 (91%) survivors, but only two of eight (25%) children who died, had serologic evidence of EBV infection at the time of PTLD diagnosis (p = 0.04). EBV seroconversion identified patients at risk for developing PTLD, but also characterized patients with sufficient immune function to survive EBV-related lymphoid proliferation. In situ hybridization for EBER1 mRNA was diagnostically helpful because it detected EBV in tissue sections of all 20 patients with B-cell PTLD, including those with negative serology.

Autopsy pathology of pediatric posttransplant lymphoproliferative disorder.

OBJECTIVES: Posttransplant lymphoproliferative disorder (PTLD) causes significant morbidity and mortality, is related to Epstein-Barr virus (EBV) infection, and is more common in children than in adults. We reviewed autopsies of children who died with PTLD to compare postmortem with antemortem PTLD histology, to assess the extent of PTLD, to document associated pathology, and to identify cause of death. METHODS: Postmortem examinations were performed on 7 patients after bone marrow (n = 3) or liver (n = 4) transplant. PTLD was classified histologically as hyperplasia or lymphoma. In situ hybridization for EBER1 messenger RNA was performed on tissue samples from all cases. EBV serologies were used to categorize infections as negative, primary, or reactive. RESULTS: PTLD was diagnosed in 5 children 12 to 35 (mean: 22) days before death, and 1.5 to 4 (mean: 3) months after transplant; PTLD was diagnosed in 2 cases at autopsy 2.5 and 4 months after transplant. Postmortem PTLD histology resembled antemortem histology; 5 PTLDs were lymphoma, 1 was hyperplasia, and 1 contained both lymphoma and hyperplasia. EBER1 messenger RNA was detected in 6 B-cell PTLDs, including lesions from patients who did not have EBV serology that indicated active infection. Complete autopsy of 4 patients who died with biopsy-proven PTLD revealed widely disseminated disease, and lymph node, brain, gastrointestinal tract, and kidney were involved in all 4 patients. Cases diagnosed at autopsy were 1 widely disseminated PTLD that had been suspected but not proven antemortem, and 1 PTLD confined to abdominal lymph nodes that was not suspected antemortem. Severe organ dysfunction (renal failure, gastrointestinal hemorrhage) was caused by massive PTLD infiltration in 2 patients. The conditions other than PTLD that contributed to morbidity and death were organ infection (5 cases), infarcts (4 cases), and diffuse alveolar damage (3 cases). CONCLUSIONS: PTLD may occur within weeks after transplant in children. The distribution of PTLD comprises a spectrum from localized and subclinical to widely disseminated and symptomatic. PTLD may cause demise quickly after the onset of signs and symptoms, through massive organ infiltration or associated conditions, such as diffuse alveolar damage. EBV serology may not accurately reflect the presence or extent of PTLD. Autopsy studies of transplant patients are necessary to identify the true incidence, natural history, and response to treatment of PTLD.

Mechanism of cooperative effects of rhinovirus and atopic sensitization on airway responsiveness.

To elucidate the mechanistic interplay between rhinovirus (RV) exposure and atopic sensitization in regulating airway smooth muscle (ASM) responsiveness, isolated rabbit ASM tissue and cultured human ASM cells were passively sensitized with sera from atopic asthmatic or nonatopic nonasthmatic (control) subjects in the absence and presence of inoculation with RV serotype 16. Relative to control subjects, atopic asthmatic serum-sensitized and RV-inoculated ASM exhibited significantly increased contractility to acetylcholine, impaired relaxation to isoproterenol, and enhanced release of the proinflammatory cytokine interleukin-1beta. These effects were potentiated in atopic asthmatic serum-sensitized ASM concomitantly inoculated with RV and inhibited by pretreating the tissues with monoclonal blocking antibodies against intercellular adhesion molecule (ICAM)-1 (CD54), the host receptor for RV serotype 16, or lymphocyte function-associated antigen (LFA)-1 (CD11a/CD18), the endogenous counterreceptor for ICAM-1. Moreover, RV inoculation was found to potentiate the induction of mRNA and surface protein expression of FcepsilonRII (CD23), the low-affinity receptor for IgE, in atopic asthmatic serum-sensitized ASM. Collectively, these observations provide new evidence demonstrating that 1) RV exposure and atopic sensitization act cooperatively to potentiate induction of proasthmatic changes in ASM responsiveness in association with upregulated proinflammatory cytokine release and FcepsilonRII expression and 2) the effects of RV exposure and atopic sensitization are mediated by cooperative ICAM-1-coupled LFA-1 signaling in the ASM itself.

Nosocomial respiratory syncytial virus infections: the cost-effectiveness and cost-benefit of infection control.

OBJECTIVE: To determine the cost-effectiveness and cost-benefit of an infection control program to reduce nosocomial respiratory syncytial virus (RSV) transmission in a large pediatric hospital. DESIGN: RSV nosocomial infection (NI) was studied for 8 years, before and after intervention with a targeted infection control program. The cost-effectiveness of the intervention was calculated, and cost-benefit was estimated by a case-control comparison. SETTING: Children's Hospital of Philadelphia, a 304-bed pediatric hospital. PATIENTS: All inpatients with RSV infection, both community- and hospital-acquired. INTERVENTION: Consisted of early recognition of patients with respiratory symptoms, confirmation of RSV infection by laboratory testing, establishing cohorts of patients and nursing staff, gown and glove barrier precautions, and monitoring and education of staff. OUTCOME MEASURES: The incidence density of RSV NI before and after the intervention was calculated as the rate per 1000 patient days-at-risk for infection. Intervention costs included laboratory testing, isolation, and administration of the program. The cost of RSV NI was estimated by comparing hospital charges for 30 cases and matched uninfected controls. RESULTS: A total of 148 patients acquired NI (88 before and 60 after the intervention). The Mantel-Haenszel stratified relative risk for NI in the period before the infection control program, compared with the postintervention period, was.61 (95% confidence interval:.53-.69). By applying the preintervention stratum-specific rates of infection to the days-at-risk in the postintervention period, an estimated 100 NIs would have been expected, which in comparison to the 60 NIs observed, yielded an estimated program effectiveness of 10 RSV NIs prevented per season. The total cost of the program per season was $15 627 or $1,563/NI prevented. In comparison, the mean cost to the hospital was $9,419/case of RSV NI, resulting in a cost-benefit ratio of 1:6. CONCLUSIONS: A targeted infection control intervention was cost-effective in reducing the rate of RSV NI. For every dollar spent on the program, approximately $6 was saved.

Detection of HCV RNA in Serum by Reverse Transcriptase-PCR and Radiolabeled Liquid Hybridization.

Hepatitis C virus (HCV) possesses a single-stranded, positive-sense RNA that is 9.4 kb in length. The complete HCV genome has been cloned and sequenced and encodes for a nucleocapsid, an envelope, and five nonstructural proteins (1,2). The 5' untranslated region of the virus is highly conserved among the HCV genotypes that have been identified to date (3-5) and has been selected by most investigators as the site for developing oligonucleotide primers and probes for the polymerase chain reaction (PCR) (6-9). PCR has proven to be a rapid, sensitive, and useful method for the detection of HCV infections (6-16). The assay can detect HCV in HCV antibody-negative individuals suspected of having hepatitis and can discriminate chronic HCV infections from resolved acute infections in patients who are positive for HCV antibody. The procedure can also be used to: 1. diagnose HCV infections in newborns of HCV-infected women; 2. resolve indeterminate serologic results; 3. monitor antiviral therapy, and 4. identify HCV infection in high-risk, seronegative individuals.

Mechanism of rhinovirus-induced changes in airway smooth muscle responsiveness.

An important interplay exists between specific viral respiratory infections and altered airway responsiveness in the development and exacerbations of asthma. However, the mechanistic basis of this interplay remains to be identified. This study addressed the hypothesis that rhinovirus (RV), the most common viral respiratory pathogen associated with acute asthma attacks, directly affects airway smooth muscle (ASM) to produce proasthmatic changes in receptor-coupled ASM responsiveness. Isolated rabbit and human ASM tissue and cultured ASM cells were inoculated with human RV (serotype 16) or adenovirus, each for 6 or 24 h. In contrast to adenovirus, which had no effect, inoculation of ASM tissue with RV induced heightened ASM tissue constrictor responsiveness to acetylcholine and attenuated the dose-dependent relaxation of ASM to beta-adrenoceptor stimulation with isoproterenol. These RV-induced changes in ASM responsiveness were largely prevented by pretreating the tissues with pertussis toxin or with a monoclonal blocking antibody to intercellular adhesion molecule-1 (ICAM-1), the principal endogenous receptor for most RVs. In extended studies, we found that the RV-induced changes in ASM responsiveness were associated with diminished cAMP accumulation in response to dose-dependent administration of isoproterenol, and this effect was accompanied by autologously upregulated expression of the Gi protein subtype, Gialpha3, in the ASM. Finally, in separate experiments, we found that the RV-induced effects on ASM responsiveness were also accompanied by autologously induced upregulated mRNA and cell surface protein expression of ICAM-1. Taken together, these findings provide new evidence that RV directly induces proasthmatic phenotypic changes in ASM responsiveness, that this effect is triggered by binding of RV to its ICAM-1 receptor in ASM, and that this binding is associated with the induced endogenously upregulated expression of ICAM-1 and enhanced expression and activation of Gi protein in the RV-infected ASM.

Effectiveness of intramuscular penicillin versus oral amoxicillin in the early treatment of outpatient pediatric pneumonia.

OBJECTIVE: To determine if intramuscular (IM) penicillin is more effective than oral (PO) amoxicillin in the early outpatient treatment of pediatric patients with presumed bacterial pneumonia. METHODS: Prospective, randomized, evaluator-blinded, clinical trial. SETTING: Pediatric emergency department (ED) of an urban children's hospital. PATIENTS: ED patients with radiographically confirmed pneumonias managed as outpatients. Patients with chronic illnesses, wheezing, allergy to amoxicillin or penicillin, recent antibiotic therapy, or concurrent diagnosis of another febrile illness were excluded. INTERVENTIONS: Patients received either a two-day supply of PO amoxicillin (50 mg/kg/day divided tid), or an IM injection of procaine penicillin G (PPG) (50,000 units/kg). They had a complete blood count (CBC), blood culture, and nasopharyngeal swab for viral culture done at initial visit. They returned in 24 to 36 hours for reevaluation. OUTCOME MEASURES: The main measures were temperature, respiratory rate, and general appearance score; additional measures were accessory muscle use, pulse oximetry, parental report of activity/oral intake. RESULTS: One hundred seventy patients were enrolled. There were no significant differences between the two groups at initial or follow-up visits with respect to temperature, respiratory rate, accessory muscle use, pulse oximetry, or parental reports of activity level and oral intake. Only in the general appearance of children less than two years of age did there appear to be a difference (P = 0.03). When subanalysis excluded patients with positive viral studies (n = 17) or chest x-rays "reread" by an attending pediatric radiologist as "no infiltrate" (n = 29), this difference disappeared (P = 0.10). Three patients in the PO group, and five in the IM group failed by all three main outcome measures (P = 1.00). Four patients in the PO group, and five in the IM group were hospitalized at the follow-up visit (P = 1.00). CONCLUSION: There does not appear to be a significant difference between PO amoxicillin and IM penicillin in the early outpatient treatment of pediatric patients with presumed bacterial pneumonia.

The clinical utility of viral quantitation using molecular methods.

BACKGROUND: The quantitation of viral nucleic acids in biological fluids has become increasingly desirable over the past several years. To this end, a number of quantitative molecular procedures have been developed. OBJECTIVES: The objective was to review the current literature on the molecular techniques used in the quantitation of viral nucleic acids and to assess the appropriateness of these methods for clinical use. RESULTS: Assays involving both target and signal amplification are now available for the accurate and precise quantitation of viral burden in infected patients. These methods include quantitative polymerase chain reaction (PCR), branched chain signal amplification (bDNA), nucleic acid sequence-based amplification (NASBA) and the SHARP signal and hybrid capture systems. Our understanding of the natural history and pathogenesis of viruses such as the human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), cytomegalovirus (CMV) and Epstein-Barr virus (EBV) may be greatly facilitated by accurate determinations of viral and infected cell burden. Quantitation of viral load in infected individuals may also be useful to assess disease progression, monitor the efficacy of therapy and to predict treatment failure and the emergence of drug-resistant viruses. CONCLUSION: Precise, accurate and reproducible quantitation of viral load is now feasible. Molecular assays for viral quantitation should have a considerable impact on medical research and clinical care.

Serious respiratory illness associated with rhinovirus infection in a pediatric population.

BACKGROUND: Rhinoviruses have long been associated with mild upper respiratory illness in both adults and children. However, the role of rhinoviruses as lower respiratory tract pathogens has not been fully characterized. Previous data suggests that rhinoviruses may cause severe lower respiratory illness in young children or infants. OBJECTIVES: The present study describes the clinical presentations, severity of illness and outcomes for a large cohort of pediatric patients with documented rhinovirus infections. SUBJECTS AND METHODS: A retrospective chart review was done on 93 pediatric patients from whom 101 nasopharyngeal or endotracheal specimens were positive by viral culture for a rhinovirus. All patients were hospitalized or seen in the pediatric emergency department at The Children's Hospital of Philadelphia between 1 January, 1990 and 31 May, 1996. RESULTS: Of the 93 patients, 52 were male and 41 female. The age range was 0 days to 18 years with 25 (27%) less than 3 months, 42 (45%) between 3 and 12 months and 26 (28%) over the age of 12 months. Clinical presentations on evaluation in the emergency department or admission included 78 (84%) patients with acute respiratory illness, 13 (17%) with fever and suspected sepsis and 11 (12%) with other complaints. Reported physical findings on examination included one or more lower respiratory symptoms or signs of acute distress and fever greater than or equal to 38.1 degrees C. A total of 64 (69%) children were noted to have significant past medical histories, including 28 (44%) with prematurity or complicated neonatal courses, 11 (17%) with prior reactive airways, 8 (12%) with congenital cardiac disease and 7 (11%) with neurologic disorders. Of the patients, 29 (31%) were considered to be otherwise healthy children with no underlying dysfunctions. The mean duration of hospitalization for 69 patients admitted with respiratory illness who did not develop subsequent unrelated complications was 3.7 days. No significant bacterial or fungal pathogens were identified in 91% of the cases. CONCLUSIONS: This study shows that rhinoviruses were associated with severe lower respiratory illness and hospitalization in a large pediatric population and that rhinovirus infection was a complicating factor in those patients with underlying or predisposing conditions.

Immunogenicity of hepatitis B vaccine in preterm infants.

OBJECTIVE: To determine the immunogenicity of hepatitis B vaccine in preterm infants when the first dose of vaccine is delayed until hospital discharge. METHODS: One hundred two preterm infants (23 to 36 weeks gestational age) born to hepatitis B surface antigen-negative mothers were enrolled. Immunization was initiated just before hospital discharge with subsequent doses 1 and 6 months later. Serum specimens were obtained before the administration of each vaccine dose and 3 months after the last dose and were tested for antibody to hepatitis B surface antigen (antiHBs). RESULTS: Eighty-seven infants (85%) completed the study. Ninety percent (n = 78) of infants who completed the study seroconverted (antiHBs > or = 10 mIU/mL); 10% (n = 9) remained seronegative at study completion. The geometric mean antibody titer to hepatitis B surface antigen for infants who seroconverted was 200 mIU/mL. Nonresponders (NR) differed from responders (R) in birth weight (NR = 2090 g, R = 1560 g) gestational age (NR = 33 weeks, R = 31 weeks), and weight gain before vaccine initiation (NR = 244 g, R = 633 g). There were no differences in weight or age at vaccine initiation, Apgar scores, interval between vaccine doses, or bacterial infections, steroid use, or transfusions before vaccine initiation. CONCLUSIONS: Ninety percent of preterm infants responded to hepatitis B vaccine when the first dose of vaccine was delayed until hospital discharge. Nonresponders were more likely to be preterm infants of higher birth weight and higher gestational age, and to have gained less weight before vaccine initiation.

What clinicians need to know about antiviral drugs and viral resistance.

The development of safe and effective antiviral therapies for the management of a variety of viral infections has expanded tremendously in recent years. Treatment is now possible for serious and potentially life-threatening infections with herpesviruses, respiratory viruses such as influenza A and respiratory syncytial virus, and the human immunodeficiency virus. The increased availability and use of antiviral drugs, however, has led to the emergence of drug-resistant viruses, especially in immunocompromised hosts. With this review, the major antiviral agents are presented with a description of the mechanisms of action, the evolution of drug resistance, and the need for in vitro antiviral susceptibility testing.

Identification of Epstein-Barr virus lytic activity in post-transplantation lymphoproliferative disease.

Post-transplantation lymphoproliferative disorder (PTLD) is a serious complication of organ transplantation. The majority of these lymphoid expansions are associated with latent Epstein-Barr virus (EBV) infection, but lytic activity may play an important role in initiating the disease process. Forty-eight specimens from 44 allograft recipients with EBV-associated PTLD were studied by immunohistochemical techniques for EBV lytic proteins, by use of monoclonal antibodies specific for the immediate early latent to lytic switch protein BZLF1 and two early antigens (diffuse and restricted). In addition, the specimens were studied by in situ hybridization for EBV DNA by use of an oligonucleotide probe for the EBV NotI tandem DNA repeats, whose expression seems confined to lytic infection. Thirty specimens were studied by in situ hybridization for immediate early (BZLF1) and late (gp350/220) lytic mRNA transcripts. Ninety-two percent of the specimens demonstrated at least one of the lytic EBV proteins. BZLF1 protein was seen in 81% of the specimens, whereas 54% and 52% of specimens expressed diffuse and restricted early antigens, respectively. Twenty-nine percent of specimens contained all three of the lytic proteins. The NotI tandem DNA probe produced staining in 88% of the specimens, whereas immediate early and late lytic transcripts were seen in 90% of the specimens. The amount of lytic activity did not significantly vary with PTLD histopathologic findings, but monomorphous proliferations localized to a single anatomic site showed a slightly lower reactivity with the antibodies and nucleic acid probes. Lytic activity was highest in patients with multisite disease, although this difference was not statistically significant. In conclusion, a significant proportion of patients with PTLD expressed lytic nucleic acids and proteins. Further work is necessary to analyze the role of lytic EBV infection in the initiation and maintenance of lymphoproliferative disorders in allograft recipients.

Cytologic manifestations of respiratory syncytial virus pneumonia in bronchoalveolar lavage fluid: a case report.

BACKGROUND: Respiratory syncytial virus (RSV) pneumonia in immunocompromised patients, especially bone marrow transplant recipients, is associated with high mortality. Early diagnosis in these cases is important because antiviral therapy with ribavirin is effective in reducing mortality. CASE: A 45-year-old male with multiple myeloma who underwent autologous peripheral stem cell transplantation subsequently developed bilateral pulmonary infiltrates. A bronchoalveolar lavage specimen demonstrated the cytologic changes associated with RSV pneumonia. Infection with RSV was confirmed by indirect immunofluorescence, enzyme immunoassay and, later, on histology and electron microscopy at autopsy. CONCLUSION: Recognition of the cytologic changes associated with RSV pneumonia in immunodeficient patients can be life saving since this would initiate confirmatory immunologic studies and therapy.