Characterization of Klebsiella isolates from natural receiving waters and comparison with human isolates.

Two hundred sixty-six strains of Klebsiella pneumoniae isolated from natural water sources in geographically diverse areas (Florida, Massachusetts, and Oregon) were analyzed to determine the serotype, biochemical, virulence, and antimicrobial susceptibility differences between these natural strains and human Klebsiella isolates. Sixty of 72 defined serotypes were found among 210 typable strains. Geographic patterns were present, but in general were not pronounced among serotypes. Reactions with 28 biochemical tests showed percentage responses which were very similar to the summaries of primarily human Klebsiella isolates (as reported by Edwards and Ewing, 1972) and that represented diverse geographic sampling. Virulence studies in representative strains showed no geographic variability and little difference from comparable hospital patient-obtained isolates. In contrast to human hospital isolates, strains demonstrated 90% or greater susceptibility to all antibiotics except ampicillin and carbenicillin; and in further contrast, there was little multiple antibiotic resistance beyond that with ampicillin and carbenicillin.