ANALYSIS OF EPIDEMIC PSEUDOMONAS-AERUGINOSA ISOLATES BY ISOELECTRIC-FOCUSING OF PYOVERDINE AND RAPD-PCR - MODERN TOOLS FOR AN INTEGRATED ANTI-NOSOCOMIAL INFECTION STRATEGY IN BURN WOUND CENTERS

The Gram-negative bacterium Pseudomonas aeruginosa is an important lif e-threatening nosocomial pathogen in burn units. In this study we anal ysed epidemic P. aeruginosa isolates from patients and their hospital environment using two new molecular techniques in order to establish s train relatedness for epidemiological purposes. One technique was pyov erdine typing by isoelectric focusing (PVD-IEF) and the other was a ge nomic PCR-based fingerprinting technique called random amplification o f polymorphic DNA actually referred to as RAPD-PCR. The described shor t epidemic (6 weeks) included 37 consecutive isolates from 9 different patients as well as two environmental isolates recovered, at the same time, from one of the hydrotherapy facilities. Only two of the three known pyoverdine types of P. aeruginosa could be found. Type I was abs ent while type II represented 49 per cent and type III, 51 per cent of the isolates. The two consecutive isolates from the environment were both of type III. The RAPD-PCR fingerprinting discriminated four patte rns. Profile I represented 60 per cent; profile 2, 34 per cent; and pr ofiles 3 and 4 only 3 per cent of the isolates respectively. The envir onmental isolates also had a RAPD-PCR 1 profile, arguing for the hydro therapy facility as a possible contamination source. Prompt measures c ould prevent an outbreak. The study demonstrates the applicability of the techniques in a routine microbiology lab as well as their usefulne ss, in combination with other techniques, in the fight against nosocom ial infections, which are so critical in burn units. Both techniques s howed undoubtable evidence of the occurrence of polymicrobial infectio n of individual patients by P. aeruginosa species. Meanwhile pyoverdin e typing by IEF seems suited to studying more profoundly the role of p yoverdines in burns. (C) 1997 Elsevier Science Ltd for ISBI.