DIAGNOSIS OF PULMONARY TUBERCULOSIS USING PCR ASSAYS ON SPUTUM COLLECTED WITHIN 24 HOURS OF HOSPITAL ADMISSION

There have been few studies evaluating the efficacy of polymerase chai n reaction (PCR) testing in front-line clinical practice. We assessed the diagnostic yield of PCR prospectively in a blinded study of patien ts admitted to rule out tuberculosis and compared PCR results to a cul ture and clinical diagnosis of tuberculosis. Specimens were sent for r outine smear, culture, and PCR analysis. Sputum sediments were submitt ed for PCR amplification of IS6110 sequences by an in-house assay and also the Roche Amplicor PCR assay targeting 16s ribosomal RNA genes. E ighty-five patients were enrolled: 27 patients had cultures positive f or tuberculosis; 12 were smear-positive. PCR by both assays on the fir st specimen picked up all patients smear-positive on any specimen. A p ositive PCR on at least one of two specimens collected in the first 24 h was 85 and 74% sensitive and 88 and 93% specific for tuberculosis b y the in-house and Roche techniques, respectively. Sensitivity in smea r-negative patients was 73 and 53%, respectively. The in-house PCR det ected 100% and Roche detected 95% of patients with more than paucibaci llary (greater than 20 colonies) tuberculosis. We conclude that PCR ma y be a useful tool to evaluate patients for tuberculosis within the fi rst hospital day.