Vol. 17, No. 40 THE JOHNS HOPKINS MICROBIOLOGY NEWSLETTER Monday, November 2, 1998
Outbreaks reported for 10/26-10/30/98: 1 gastroenteritis in a nursing home, 1 foodborne gastroenteritis in an assisted living facility, 2 foodborne gastroenteritis in food service facilities (restaurants), 1 pneumonia in a school, 1 influenza-like illness in a health care facility, and 1 scabies in a shelter Case Report: This 20 year old man underwent autologous BMT for chemotherapy-resistant large cell lymphoma, B-cell type, stage Ia. Initial therapy included tumor excision, thymectomy, six cycles of CHOP and a platinum and etoposide-based regimen for recurrent disease. He was admitted one day after his bone marrow was harvested, for his 10 day preparative regimen consisting of Cytoxan and total body irradiation. During his aplasia he received prophylactic acyclovir, fluconazole, and norfloxacin and was started empirically on piperacillin/tazobactam for a fever 3 days post-transplant. On day 11 post transplant, the patient developed dysuria and within two days frank blood clots were noted in his urine. A urine culture taken on day 3 post-tx was positive for adenovirus (AdV) on day 14 of culture and all subsequent urine cultures remained positive for AdV. Approximately one month after his autologous bone marrow infusion (ANC>500), he developed a fever and increasing respiratory distress requiring intubation and mechanical ventilation. Blood cultures remained negative. A BAL and an open lung biopsy were performed and sent for culture. Three weeks later cultures from the BAL were positive for adenovirus. Additionally, the patient developed bilateral conjunctivitis. Conjunctival swabs were sent for culture and were positive for AdV on day three of culture. The patient's status continued to decline with worsening liver and renal functioning and bone marrow aplasia. Ribavirin therapy was initiated 10 weeks post-tx however; the patient developed multi-organ system failure and died on day 80 post-tx. Organism: Human adenoviruses are nonenveloped, double-stranded DNA viruses of the family Adenoviridae. They are icosahedral in shape and consist of 10 structural proteins. Adenoviruses replicate in the cell nucleus and are host species specific. In each virion are 240 hexons and 12 pentons. All adenoviruses possess genus-specific antigenic determinants on the hexon capsomeres. A classification scheme based on hemagglutination properties allows separation of the human adenoviruses into six subgroups (A-F). At least 49 human adenovirus serotypes are recognized and associated with distinct clinical manifestations. Clinical Manifestations: Adenoviruses have been associated with many clinical syndromes, including upper and lower respiratory illnesses, acute respiratory disease, keratoconjunctivitis, hemorrhagic cystitis, hepatitis, and gastroenteritis, as well as systemic illness in the immunocompromised host. While specific serotypes have been associated with involvement of particular organ systems, multiple localized infections in the immunocompromised host may be a manifestation of disseminated infection caused by a single adenovirus serotype. Given the increasing prevalence of acquired deficiencies in immune function due to organ transplantation, chemotherapy regimens and HIV infection, adenovirus infections have become increasingly important. Adenoviruses cause disseminated illness in about 10% of such patients and is often fatal. Slow and insensitive culture technologies have made objective diagnosis of disseminated AdV infection difficult, perhaps making its clinical importance and range of presentations in the immunocompromised host. Laboratory Diagnosis: Adenoviruses produce characteristic cytopathic effects (CPE) that are accompanied by accumulation of multiple antigenic components in the host cell culture fluids. Isolation of adenovirus can take days to weeks for identification with an inadequate or unknown sensitivity, particularly in the setting of an immunocompromised host receiving passively transferred antibodies through multiple transfusions of blood products. Detection of AdV by biopsy and surgical pathology review, as well as by direct antibody fluorescence and immunohistologic staining has proven to be insensitive. Assays for detection of serologic antibodies are generally not helpful, as they may yield positive results due to a prior infection. The limitations of the above techniques emphasize the need for a more rapid and sensitive diagnostic laboratory method. A new diagnostic PCR method for detection of AdV in the urine developed in our institution is now available in the Molecular Microbiology Laboratory of the JHH Microbiology Division. AdV DNA is extracted from urine and then amplified using primers specific to the hexon gene common to all 18 serotypes of AdV tested to date, as described by Echavarria et al (1). The 139 bp PCR product is detected by agarose gel electrophoresis and Southern blot hybridization. The analytical sensitivity is 0.2 PFU/ml for AdV serotype 11, and 10 copies of DNA for AdV serotype 2. The test requires 0.5 cc of urine and is performed on Wednesdays at 4:00 p.m. with results available at 4:00 p.m. the following day. The detection of AdV in urine using PCR provides a non-invasive, rapid, sensitive and specific alternative laboratory test to aid in the diagnosis of AdV infection. Follow up: In this case, AdV was detected by PCR in the urine while the patient was asymptomatic (14 days prior to the development of hematuria and hemorrhagic cystitis) from a pre-tx surveillance urine sample, suggesting that disease in this patient may have been due to reactivation of latent virus. The patient clearly had disseminated AdV infection based on positive AdV cultures (and experimental PCR results) from urine, BAL and conjunctiva specimens. The episode of cystitis appeared to have been the initial event. Viral isolates in this patient recovered during clinical symptomatology from urine, conjunctiva and BAL were serotyped and all were identified as AdV serotype 11. Further, isolates from urine and conjunctiva were analyzed by restriction endonucleases and were identified as belonging to genome type 11c. Blood and bone marrow cultures sent on post-tx day 45 and 52, respectively remained negative for AdV. However, blood and bone marrow samples from post-tx day 73 and 52, respectively were both positive for AdV using the PCR-based method. Identification of AdV DNA by PCR in blood and bone marrow that had been previously reported as culture-negative provided documentation of systemic involvement of AdV, consistent with this patient's overall clinical picture. References: