Optimal method for recovery of cytomegalovirus from urine of renal transplant patients

Optimal recovery of cytomegalovirus from urine as a function of specimen preparation

Cytomegalovirus (CMV) is a significant pathogen among immunocompromised patients. We compared supernatant and sediment fractions of centrifuged urine for the optimal recovery of CMV by shell vial culture and polymerase chain reaction (PCR). Of 336 urine specimens, 31 (9.23%) were positive by shell vial culture; of these 29 (93.5%) were identified using the sediment fraction and 17 (54.8%) using the supernatant fraction (p = 0.001, chi2). Of the 29 positive sediment fraction specimens, 24 (82.8%) were identified as CMV positive at 24 h and 5 (17.2%) were identified as positive at 48 h. Two (0.064%) of the total 31 positive specimens were lost to microbial contamination in the sediment inoculated cultures. Of the 17 supernatant fraction specimens, 9 (53.9%) were identified as CMV positive at 24 h and 8 (47.1%) were identified as positive at 48 h. Fourteen (45.2%) of the total 31 positive specimens were lost to either toxicity or microbial contamination in the sediment-inoculated cultures. Thirty-four CMV culture-positive specimens were tested by PCR; 5 of these specimens (14.7%) were PCR negative for both sediment and supernatant fractions; 26 (76.5%) were found to be positive using the sediment fraction and negative using the supernatant; 3 (8.8%) were PCR positive for both the sediment and the supernatant. None of the 34 was identified as positive using the supernatant fraction only (p = 0.001, chi2). These findings demonstrate that the method of specimen preparation can significantly affect the outcome of diagnostic testing for CMV from urine specimens.

Nonpulmonary manifestations of cytomegalovirus infection in immunocompromised patients

Nonpulmonary manifestations of cytomegalovirus (CMV) infection in immunocompromised patients include chorioretinitis, gastrointestinal infection, and central nervous system disease. Diagnosis of end organ disease, especially in the gastrointestinal tract, is best substantiated by histologic evidence of CMV inclusions. Positive cultures of CMV provide evidence for supporting infection but do not define actual end organ disease. Satisfactory treatment of the disease can be accomplished with ganciclovir or foscarnet, although these agents only suppress virus replication. In many instances, severe CMV-induced end organ disease in immunocompromised patients will progress despite treatment. In some instances, resistance to the antiviral agent is the basis for drug failure. Patients at high risk for CMV disease can be identified, and studies of prophylaxis are in progress.

Combined use of sonication and monoclonal antibodies for the detection of early and late cytomegalovirus antigens in centrifugation cultures

A total of 157 clinical specimens was inoculated into shell vials and conventional tube cell cultures containing confluent monolayers of human embryonic lung fibroblasts (HELF). Of 31 clinical cytomegalovirus (CMV) isolates, 30 specimens (96.8%) were positive by the immunofluorescence method on centrifugation vial cultures (CVC-IF), whereas the cytopathic effects (CPE) of CMV were detected in only 14 specimens (45.2%) in conventional tube cell cultures (CCC), P less than 0.001 and in 22 specimens (70.9%) in centrifugation vial cultures (CVC-P), P less than 0.1. Significantly more fluorescent foci were detected in centrifugation cultures inoculated with sonicated urine samples (P less than 0.001). CVC-P is more sensitive than CCC for the diagnosis of CMV (P less than 0.05), and a highly significant difference was observed when we compared the mean day to initial detection of CPE (P less than 0.001). For optimal detection of CMV, both CVC-IF and CVC-P should be used for the laboratory diagnosis of this virus infection.

Comparison of MRC-5 and HFF cells for the identification of cytomegalovirus in centrifugation culture

Detection of cytomegalovirus (CMV) by centrifugation culture was compared in MRC-5 and HFF cells. At 24 hr 47 of 130 specimens (36%) were positive for CMV, 45 in MRC-5, and 35 in HFF cells. At 48 hr 45 specimens were positive in both MRC-5 and HFF cells. MRC-5 cells appear to be superior for the detection of CMV at 24 hr in centrifugation culture; however, both lines are comparable at 48 hr.

Practical protocol for cytomegalovirus isolation: use of MRC-5 cell monolayers incubated for 2 weeks

Isolation of cytomegalovirus (CMV) in tissue culture is presently the most reliable means of proving active CMV infection. To improve both the cost-effectiveness and clinical usefulness of procedures for the isolation of CMV from fresh clinical specimens, we analyzed results obtained with standard isolation procedures and compared them with results obtained under different conditions. Cell monolayers from commercial sources were inoculated with fresh specimens and then were observed for a cytopathic effect typical of CMV. Of 1,375 specimens submitted over a 12-month period, 6.4% were CMV positive in WI-38 monolayers within 28 days after inoculation. The mean day of CMV detection for 45 urine, 13 cervical-vaginal, and 5 saliva specimens was 6.7 +/- 3.1 (mean +/- standard deviation), 9.9 +/- 3.3, and 7.7 +/- 3.3 days, respectively, and 92% were positive within 14 days. When 1,058 subsequent specimens were inoculated in parallel onto WI-38 and MRC-5 cell monolayers, 8.7% were positive for CMV. MRC-5 cells were significantly more sensitive than WI-38 cells: 98% of all positive specimens appropriate for comparison were detected in MRC-5 cultures, but only 85% were detected in WI-38 cells. Although 1 specimen was positive in WI-38 cells only, 38% of all isolates were positive earlier (16 specimens) or only (10 specimens) in MRC-5 cultures. Based on these data, we have developed a practical 2-week protocol for CMV isolation from fresh clinical specimens that includes the use of MRC-5 cell monolayers incubated at 36 degrees C.