Could the DiversiLab® semi-automated repetitive-sequence-based PCR be an acceptable technique for typing isolates of Pseudomonas aeruginosa? An answer from our experience and a review of the literature.

Recently the DiversiLab® (DL) system (bioMérieux) was developed as an automated platform that uses repetitive element polymerase chain reaction (rep-PCR) technology for standardized, reproducible DNA fingerprinting of bacteria. The purpose of this study was to evaluate the usefulness of DL rep-PCR for typing Pseudomonas aeruginosa isolates. The performance of DL rep-PCR was compared with that of pulsed-field gel electrophoresis (PFGE) in a prospective multicenter study of patients with ventilator-associated pneumonia due to P. aeruginosa, conducted in 3 intensive care units over a 31-month period. In total, 203 P. aeruginosa isolates from 66 patients, from whom at least 2 consecutive respiratory samples each were collected more than 48 h apart, were typed using DL rep-PCR. Forty isolates (corresponding to 20 patients) were also typed using PFGE of SpeI-digested DNA. The typeability was 100% with DL rep-PCR and 95% with PFGE. The discriminatory power was close for DL rep-PCR and for PFGE (Simpson's diversity indices of 0.901 and 0.947, respectively). Insufficient agreement between DL rep-PCR and PFGE typing results was observed for the 40 selected isolates (adjusted Rand coefficient of 0.419), mostly due to isolates of the same DL rep-PCR type but of different PFGE types (adjusted Wallace coefficients of 0.306 for DL rep-PCR with PFGE, and of 0.667 for PFGE with DL rep-PCR). Considered together with published data, DL rep-PCR results should be interpreted with caution for the investigation of outbreaks caused by P. aeruginosa and evaluated in conjunction with epidemiological data.