Comparison of six different methods for typing Pseudomonas aeruginosa strains isolated from bottled and well waters

Twenty-three strains of Pseudomonas aeruginosa isolated from bottled and well waters were biotyped, serotyped and examined by antimicrobial susceptibility, plasmid content, analysis of chromosomal DNA Eco RI ribopatterns (ribotyping) and by a PCR-based procedure. Phenotypic methods showed poor discrimination power between strains, and plasmids were detected in 29% of isolates. Southern blot hydridisation analysis showed genetic diversity between isolates, and six different ribotypes were defined. Arbitrarily primed polymerase chain reaction (AP-PCR) analysis also differentiated between the strains with higher discriminatory power than ribotyping, since 13 different profiles were obtained. Both DNA-based methods are valuable alternatives to traditional typing systems for P. aeruginosa, and AP-PCR could be particularly useful for epidemiological studies.