Detection of Cytomegalovirus,Pneumocystis carinii, and Aspergillus Species in Bronchoalveolar Lavage Fluid:A Comparison of Techniques

Abstract

Cytomegalovirus (CMV), Pneumocystis carinii, and Aspergillus species are common causes of fatal pulmonary infections in immunocompromised hosts. Therefore, rapid and reliable methods of establishing the diagnosis of these types of pneumonia are essential. Bronchoalveolar lavage (BAL) has proved to be a rapid and safe procedure for procuring large numbers of bronchial and alveolar cells from the lung. To assess various methods of detecting CMV, P. carinii, and aspergillosis in lavage specimens, 47 BAL samples from adults at high risk for these infections were evaluated. The visualization of these agents was performed by cytologic examination and in situ hybridization for CMV; cytologic examination, Gomori's methenamine silver (GMS) stain, and immunofluorescence for P. carinii; and cytologic examination, GMS stain, and immunocytologic studies for Aspergillus species. Cytomegalovirus was detected in 2 of 47 specimens (4%) by cytologic examination and 7 of 47 (15%) by in situ hybridization. Cells with nuclear and/or cytoplasmic inclusions invariably were labeled with the CMV DNA probe. The weak diagnostic value of the cytologic examination resulted from the absence of characteristic inclusions in many specimens with positive results by in situ hybridization. P. carinii was the most frequent pathogen isolated from BAL fluid (9 of 47 cases; 19%). It was found in 1 of 47 specimens (2%) by the cytologic examination of Papanicolaou-stained smears, 4 of 47 (8.5%) by the GMS stain, and 8 of 47 (17%) by immunofluorescence. Most P. carinii-positive cases (five of nine cases) were detected by immunofluorescence only. Aspergillus species was diagnosed in 2 of 47 specimens (4%) by cytologic examination and GMS staining. Immunocytologic studies had positive results in these specimens and detected one additional case of Aspergillus infection (3 of 47 cases; 6%). These data show that techniques using CMV DNA probes and anti-P. carinii or anti-Aspergillus antibodies are rapid and more sensitive than conventional diagnostic procedures.