An outbreak of respiratory syncytial virus infection in a bone marrow transplant unit: effect on engraftment and outcome of pneumonia without specific antiviral treatment.

Immunocompromised haematological patients are at high risk for severe, often fatal, respiratory syncytial virus (RSV) pneumonia. In the 2001 winter season, 16 of 195 (8.2%) adult haematological in-patients were diagnosed with RSV infection. Eight patients had undergone stem cell transplantation. The median age was 53 years (range 20-67). A total of 11 patients had nosocomial RSV infection while the rest (five) had community-acquired infection. All patients were febrile and had upper respiratory tract infection (URTI). Eight patients (50%) developed lower RTI. Two of the 16 patients (12.5%) died of respiratory failure, due to the RSV pneumonia, despite ICU admission and supportive ventilation. None of the studied patients received ribavirin therapy or specific RSV immunoglobulin. Two patients autografted for multiple myeloma (MM) showed delayed neutrophil and platelet engraftment despite receiving an adequate dose of stem cells. A third patient undergoing a CD34+ selected HLA-matched sibling mini-allograft for relapsed MM showed graft failure shortly after RSV infection. In our series, RSV infection was concurrent with an outbreak in the community. Unlike other published series, no specific antiviral treatment for RSV pneumonia was used and yet the overall outcome in our patients was favourable. Furthermore, RSV infection in the pre-engraftment period after autologous transplantation was associated with delayed engraftment.

Rapid detection, culture-amplification and typing of herpes simplex viruses by enzyme immunoassay in clinical samples.

BACKGROUND: The laboratory diagnosis of herpes simplex infection may require rapid (direct) tests, as well as cell cultures, for detection of the virus in clinical samples. The quantity of virus present in clinical samples is variable and this may depend on the period from onset of rash. In addition, not all patients may show obvious symptoms with this infection. The successful culture of herpes simplex virus requires prompt transportation after collection of the specimen as the virus is easily inactivated. Hence, rapid and culture tests would enable detection of non-viable and viable viruses. STUDY DESIGN: We describe the rapid detection of HSV by EIA directly in various clinical samples using commercially available polyclonal sera. In addition specimens were inoculated in microwell cell cultures and 4 days post inoculation the culture fluids were tested for HSV and subtyped by a similar EIA (culture amplified EIA). RESULTS: The direct EIA showed an endpoint detection of 100 TCID50/ml, sensitivity of 92% (all specimen types) and specificity of 100%. The direct EIA sensitivity was 97% in non-genital specimens and 88% in genital specimens. The culture amplified EIA showed a sensitivity of 95% compared to all confirmed HSV positive samples. CONCLUSIONS: The results of the HSV rapid tests were available within 24 h from receipt of specimens. Specimens which were culture negative/direct EIA positive were confirmed by blocking antisera. Culture positive specimens which were direct EIA negative were confirmed by subtyping of the virus.

Detection of Chlamydia trachomatis in urine samples by nucleic acid tests: comparison with culture and enzyme immunoassay of genital swab specimens.

Two commercially available nucleic acid-based tests, ligase chain reaction (LCR; Abbott Laboratories) and PCR (Roche Diagnostics), for the detection of Chlamydia trachomatis in male and female urine samples were compared with culture and enzyme immunoassay (EIA) (Microtrak; Syva) for C. trachomatis detection in genital samples. The samples were collected from 1,005 patients who attended a sexually transmitted disease clinic. In this study population, the prevalence of the infection was 4%. Specimens which were reactive in any of the tests were retested with a different PCR test using primers directed against the major outer membrane protein gene. With a "gold standard" of a positive culture, or any other positive test result if it was confirmed by an independent test, the Roche PCR (95% sensitive, 99.9% specific) was more sensitive than the LCR (75% sensitive, 100% specific) (chi2, P < 0.0001) while both tests were more sensitive than culture (58% sensitive, 100% specific) or EIA (45% sensitive, 100% specific) (chi2, P < 0.001). The Roche PCR and Abbott LCR tests of urine identified 65% and 30% more positive patients, respectively, than did testing by culture of urethral or cervical specimens. Nucleic acid testing of urine specimens for C. trachomatis is a more sensitive and convenient method for the detection of genital infection.

Rapid diagnosis of chlamydial respiratory infection in children.

A study was undertaken to determine the incidence of chlamydial respiratory infection in paediatric patients during a 12-month period by antigen detection. Nasopharyngeal aspirates (NPA) from 514 patients were screened for genus-specific chlamydia antigen using the Pharmacia Chlamydia enzyme immunoassay (EIA) and Kallestad immunofluorescence (IF) assays. EIA screen-positive samples were confirmed by specific blocking antibody. Specimens which were EIA positive or IF positive were cultured for chlamydia. The NPAs from 7 patients were positive in the EIA and IF assays. Four of these patients were culture positive for chlamydia. Our results showed that the incidence of chlamydia respiratory infection by antigen detection was 1.4% or 0.8% if confirmed by culture.

Outbreak of adenovirus type 4 conjunctivitis in South Australia.

An outbreak of adenovirus type 4 conjunctivitis occurred in South Australia between April and November 1992. Eye swabs were submitted by general practitioners and ophthalmologists who had seen patients with clinical conjunctivitis or keratitis. Apart from interfamilial spread, there were no other common epidemiological factors. Adenovirus was isolated from the eye swabs of 38 patients. Isolates were typed by neutralisation tests and restriction endonuclease cleavage patterns and found to be adenovirus type 4. This report serves to illustrate an infrequent cause of epidemic conjunctivitis, namely adenovirus type 4. There was no demonstrable focus of the outbreak.

The use of MDCK, MEK and LLC-MK2 cell lines with enzyme immunoassay for the isolation of influenza and parainfluenza viruses from clinical specimens.

Primary Monkey Kidney (PMK) epithelial cells or egg inoculation have been traditionally used for the culture of influenza and parainfluenza viruses. The high cost and variability of obtaining high quality PMK cells prompted us to investigate the use of other cell strains for the growth of these viruses. For this study we investigated three cell lines viz. MDCK, MEK and LLC-MK2 for the culture of influenza A and B and parainfluenza 1, 2 and 3 viruses. Clinical specimens were spun onto cell monolayers in microtitre wells. The growth of these viruses was then identified by specific antibodies in an enzyme immunoassay (EIA). The LLC-MK2 and MDCK cell lines were found to provide optimal growth of parainfluenza and influenza viruses respectively. During the period from November, 1990 to July, 1992, 6501 respiratory specimens were tested. There were 100 influenza A, 36 influenza B and 261 parainfluenza virus isolates. The influenza isolates were further subtyped by the WHO Influenza Reference Centre. The use of these cell lines and the EIA provided an effective method for the routine culture of these viruses.