Direct in situ hybridization for rapid detection of cytomegalovirus in bronchoalveolar lavage

Abstract

Rapid detection of cytomegalovirus (CMV) from pulmonary specimens in immunosuppressed persons may provide an origin for pneumonia. In situ DNA hybridization has been effective for detection of CMV in otherwise nondiagnostic histologic material. Studies comparing bronchoalveolar lavage (BAL) with open-lung biopsy have shown the former to be superior in detecting most pulmonary pathogens affecting immunocompromised patients. Fifty consecutive BAL specimens were studied to compare direct in situ DNA hybridization, routine tissue culture, and conventional cytologic examination to assess the efficacy of the hybridization technic to rapidly detect CMV. Using tissue culture as the standard, a sensitivity of 90% (28 of 31) and specificity of 63% (12 of 19) were observed with the CMV probe. Discrepant results between the probe and tissue culture were present in ten cases. There were seven probe-positive, culture-negative cases, three of which had systemic CMV infection, including two patients with inclusions noted by conventional cytologic examination. Three probe-negative, culture-positive cases were found. In the authors' laboratory, the predictive value of a positive CMV probe is 80% (28 of 35). In contrast to the probe, conventional cytologic examination revealed CMV inclusions in only 23% (7 of 31) of the culture-positive cases. An average of 21 days was required for CMV cultures to become positive; probe results were available within 24 hours. The authors conclude direct in situ DNA hybridization is a useful rapid method for the detection of CMV in BAL specimens submitted for cytologic examination.