Antibiotic resistance of faecal Enterobacteriaceae isolated from healthy volunteers, a 15-week follow-up study.

From 25 March to 1 July 1991 faecal samples from healthy volunteers of two cities and their rural surroundings, Weert (n = 91) and Roermond (n = 96) were collected weekly and analysed for the presence of Enterobacteriaceae, resistant to ampicillin, ciprofloxacin, nalidixic acid, neomycin, nitrofurantoin, oxytetracycline, sulphamethoxazole or trimethoprim. In total, 682 and 690 samples from Weert and Roermond, respectively, were analysed for the prevalence and the degree of resistance to each antimicrobial agent. The mean prevalence of resistance of the samples from Weert varied from 28% +/- 12 (mean +/- S.D.) for ampicillin to 0.1% +/- 1 (range 0-2%) for ciprofloxacin. For Roermond the prevalence of resistance varied from 41% +/- 7% for sulphamethoxazole to 0% for ciprofloxacin. The high degree of resistance (i.e. > 50% of the faecal flora of one particular individual) varied from 8% +/- 4 for sulphamethoxazole to 2% +/- 2 for trimethoprim for Weert. For Roermond the figures varied from 14% +/- 4 for sulphamethoxazole to 0.3% +/- 1 (range 0-2%) for nalidixic acid. High degrees of resistance were not found for ciprofloxacin and nitrofurantoin in either city. In Weert ampicillin-resistant Enterobacteriaceae were isolated from 69/91 individuals.