Biotinylated DNA probes for exotoxin A and pilin genes in the differentiation of Pseudomonas aeruginosa strains

Biotin-labeled DNA probes derived from Pseudomonas aeruginosa exotoxin A and pilin genes were tested for their ability to distinguish strains among a selected group of P. aeruginosa isolates. Probing of Southern blots of restriction digests of DNA from test strains with the exotoxin A probe demonstrated a unique hybridization pattern for each independently isolated strain containing the exotoxin A gene. Two phenotypically distinct strains isolated from the same patient were found to be identical in their DNA hybridization patterns. By using a pilin gene probe, similar distinction was made between independent strains, while strains from the same source were confirmed to be identical. Furthermore, DNA from a strain of P. aeruginosa lacking the exotoxin A gene yielded a unique pattern of restriction fragments which hybridized to the pilin gene probe. The exotoxin A and the pilin probes may together prove to be useful tools in epidemiological surveys during outbreaks of P. aeruginosa infection.