Distribution, serological grouping, elastase production and antimicrobial susceptibility of 541 Pseudomonas aeruginosa strains from river water

Abstract

In order to determine the epidermiological background of human Pseudomonas aeruginosa infection and to estimate the degree of environmental pollution by this organism, distribution of P. aeruginosa in the Murasaki River water was investigated. The serogroups and elastase-producing ability of 541 P. aeruginosa isolates and the antimicrobial susceptibility of 481 isolates were compared with those of strains of clinical origin.The results obtained were as follows:1) Of each 85 water samples from the upper and lower part of the river, in July 1978, 41 (48.2%) and 64 (75.3%) samples, respectively, yielded P. aeruginosa by enrichment culture technique. Two months later (September), the isolation frequency was lowered up to 13.0% for upper part and 69.0% for lower part of the river.2) Number of living cells of P. aeruginosa in the river water was determined by membrane filter technique. Each 100ml water of upper and lower part of the river contained 101 and 102 cells, respectively.3) Main serogroups of the isolates from the lower part of the river were G, I, B, E, and A, similar to those of clinical isolates reported in the literature.4) Out of 541 isolates from the Murasaki River water, 530 (98.0%) were positive for elastase production. This result suggests that elastase-producing ability of P. aeruginosa is not a particular charcter for those of pathological origin, but common in almost all isolates from the environment.5) All 481 P. aeruginosa strains from the Murasaki River water were sensitive to gentamicin, dibekacin, and colistin. Sensitivity rate of strains for carbenicillin, tetracycline, and minocycline was 93-99% in the upper part isolates and 69-76% in the lower part isolates.