Evaluation of the efficacy of real-time polymerase chain reaction for the routine early detection of Pseudomonas aeruginosa in cystic fibrosis sputum and throat swab specimens

A longitudinal study of 2099 sputa and throat swabs received from 183 pediatric cystic fibrosis patients over a 29-month period was used to evaluate the efficacy of real-time polymerase chain reaction (PCR) for the early detection of Pseudomonas aeruginosa as compared to microbiologic culture. Real-time PCR resulted in an increased number of specimens identified as P. aeruginosa positive. The sensitivity of culture was 82% (373/453) and of PCR was 93% (420/453) when considering both positive culture and PCR results as true positives. Of the 80 specimens identified as PCR positive/culture negative for P. aeruginosa, the subsequent patient sample in 32.5% (26/80) of specimens concerned was identified as P. aeruginosa culture positive, suggesting that PCR has the potential to detect P. aeruginosa earlier than the microbiologic culture. Real-time PCR analysis found no evidence of the Liverpool and Manchester epidemic P. aeruginosa strains in the cohort examined. The findings of this study highlight the importance of specimen collection protocols to ensure that adequate samples are received at the laboratory for testing, thereby minimizing the potential for reporting of false-negative P. aeruginosa culture results.