Antibiotic Resistance and R Factors in Coliform Bacilli Isolated from Hospital and Domestic Sewage

SUMMARY One-hundred and one samples from a wide variety of sewers and water-drainage channels in Bristol, including some sewers that separately drained hospital and domestic premises, were examined for antibiotic-resistant coliform bacilli and for R factors. The antibiotic-sensitivity patterns of over 3000 coliform bacilli isolated were obtained and 1000 resistant strains were tested for R-factor transfer. Hospital sewage contained more coliform bacilli with much higher proportions of resistant bacteria, more R factors, and a greater proportion of R factors carrying multiple resistance, than sewage from domestic and other sources. Despite these findings, it was calculated that less than 5% of the R factors in the sewage output of the City of Bristol originate in hospitals. The normal, healthy population appears to be by far the greatest reservoir of R factors in the community.