Detection of cytomegalovirus (CMV) in HIV+ patients:: comparison of cytomorphology, immunocytochemistry and in situ hybridization

CMV is regarded as an important pathogen in immunocompromised patients(1-3). This study compares three cytological methods of diagnosis of CMV in alcohol-fixed smears from bronchoalveolar lavage (BAL) specimens from 40 HIV+ patients, using cytomorphology (CM), immunocytochemical staining (ICC) and in situ hybridization (ISH). The results of CM are compared with virological detection methods using the detection of early fluorescent foci (DEAFF) 48-h culture technique and virus isolation studies (VISO 1). ICC was the most sensitive technique, identifying CMV in 13 cases, six of which were also positive on ISH. Cytomorphology was the least sensitive, with only one case showing diagnostic features of CMV cytopathic effect. One additional case showed morphological features suggesting viral infection but not specific for CMV. Both of these cases were confirmed by ICC and ISH, Virology studies identified CMV in all 13 cases and in an additional five cases. ICC detected two cases which were negative on the DEAFF test but which were later detectable by the VISO 1 technique. These findings support the usefulness of ISH and ICC in confirming CMV in cases where the infection was suspected on cytomorphological features. ISH and ICC also increase the detection of CMV in BAL smears not showing morphological features on CM.