Usefulness of Real Time PCR in diagnosing initial Pseudomonas aeruginosa infection in Cystic Fibrosis pediatric patients

摘要

Chronic infection with Pseudomonas aeruginosa is the main agent responsible for lung function decline in Cystic Fibrosis patients.To prevent chronic colonization, timely identification of P. aeruginosa in the airways is crucial subsequently followed by eradication therapy. It is therefore necessary to use highly sensitive and specific methods. Our aim was to test the real-time PCR assay method to identify P. aeruginosa growth from CF respiratory specimens and compare it with conventional microbiological cultures. 754 sputum samples from 96 CF paediatric patients were processed between November 2009 and April 2011 with Real-Time PCR assays in addition to conventional microbiological cultures. Patients were categorized according to their P. aeruginosa infection status in three groups: “chronic infection”, “intermittent infection”, “negative”. From 16 chronic patients, seven cultures out of 138 (5%) were found to be positive using RT-PCR and then negative after cultures; from 29 intermittent patients, 18 out of 59 (30.5%) samples were positive only using the PCR method; from 51 negative patients, 13 out of 39 (33%) specimens were positive only with PCR. No false negative PCR results were detected when conventional cultures were positive. Real-Time PCR test was more sensitive in identifying P. aeruginosa in “intermittent infection” or “negative” patients. Clinical trials are needed to explore the usefulness of starting eradication Pseudomonas therapy on the basis of only a positive PCR test, without waiting for the bacterial growth on conventional microbiological cultures.The usefulness of real time PCR could also be tested in the follow-up of eradication therapy efficacy.