Direct amplification of rRNA genes in diagnosis of bacterial infections

A broad-range bacterial PCR targeting rRNA genes (rDNAs) was used to direct ly analyze 536 clinical samples obtained from 459 hospitalized patients dur ing a 4-year study period. The molecular diagnosis based an DNA sequencing of the PCR product was compared to that obtained by bacterial culture. The bacteriological diagnosis was concordant for 447 (83%) specimens. Broad-ran ge rDNA PCR was the only method that yielded an etiologic diagnosis for 11 (2.4%) of 459 patients. Compared to culture and clinical assessment, the se nsitivity of the PCR method combined with sequencing was 74.2%, and the spe cificity was between 98.7 and 99.6%. At present, the described molecular ap proach proved superior to bacterial culture in two clinical situations: inf ections caused by bacteria with unusual growth requirements and specimens t aken during antimicrobial treatment of the patient.