DIRECT QUANTITATIVE COMPARISON OF SHELL VIAL AND CONVENTIONAL CULTUREFOR DETECTION OF CMV VIREMIA

Background: Centrifugation shell vial (SV) and conventional tube cultu re (TC) are the most common methods for detecting cytomegalovirus (CMV ) viremia. Studies have indicated that SV is more sensitive than TC bu t at least one report suggested that TC was more sensitive. Because CM V in the blood is primarily associated with infected leukocytes, the n umber of leukocytes inoculated into the different culture systems coul d affect the sensitivities of the two systems. Objectives: To compare the sensitivities of SV and TC for detection of CMV viremia by inocula ting equal numbers of leukocytes into paired SV cultures and TC cultur es. Study design: Leukocytes from transplant recipients were isolated and counted. Equal numbers of leukocytes were then inoculated into eac h of two MRC-5 SV and into each of two MRC-5 TC. SV was considered pos itive when either one or both vials were positive, and TC was consider ed positive when either one or both tubes showed evidence of CMV cytop athic effect (CPE). Results: From a total of 434 specimens tested, 85 (19.6%) were positive by SV or TC. CMV was detected by SV in 75 (88%) of the positive specimens, compared to TC which was positive in 40 (47 %) of the positive specimens. Conclusions: When equal numbers of leuko cytes were inoculated into each system, SV had significantly greater s ensitivity than TC for detecting CMV viremia. However, a small number of episodes of viremia were detected only by TC. Therefore, both metho ds should be used for maximum sensitivity.