Cytomegalovirus (CMV) DNA quantification in bronchoalveolar lavage fluid of immunocompromised patients with CMV pneumonia

Cytomegalovirus (CMV) pneumonia causes major morbidity and mortality. Its diagnosis requires demonstration of viral cytopathic changes in tissue, entailing risks of lung biopsy. This study aimed to determine CMV viral load (VL) thresholds in bronchoalveolar lavage fluid (BALF) for diagnosis of CMV pneumonia in immunocompromised patients. CMV VL in BALF was studied in 17 patients (83% transplant recipients) and 21 control subjects with and without CMV pneumonia, respectively, using an FDA-approved PCR assay (Cobas^® AmpliPrep/Cobas TaqMan^® CMV Test, Roche Molecular Systems, Inc.) calibrated to the WHO International Standard for CMV DNA (NIBSC: 09/162). Receiver operating characteristic curve analysis produced a BALF CMV VL threshold of 34 800, IU/mL with 91.7% sensitivity and 100.0% specificity for diagnosis of possible, probable, and proven CMV pneumonia in transplant patients, while a threshold of 656 000 IU/mL yielded 100% sensitivity and specificity among biopsy-proven cases. For all immunocompromised patients, a VL threshold of 274 IU/mL was selected. VL thresholds also were normalized to BALF cell count yielding a threshold of 0.32 IU/10⁶ cells with 91.7% sensitivity and 90.5% specificity for possible, probable, and proven CMV pneumonia in transplant recipients. Monitoring CMV VL in BALF may be a less invasive method for diagnosing CMV pneumonia in immunocompromised patients.