Antibiotic resistance of Enterobacteriaceae isolated from the faecal flora of fattening pigs.

From June 1991 to April 1992 407 faecal samples were collected from three groups of pigs (I n = 248, II n = 87, III n = 72) at a pig fattening farm to determine the prevalence and the degree of antibiotic resistance of Enterobacteriaceae as well as the antibiotic susceptibility of the strains isolated. Despite the absence of mass medication during the observation period, the prevalence of resistance to the most commonly used antimicrobial agents in veterinary medicine was high (range amoxicillin 70%-97%, oxytetracycline 89%-100%, sulfamethoxazole 88%-100%, trimethoprim 78%-100%). The high degree of resistance to oxytetracycline and sulfamethoxazole ranged from 8%-67% and 4%-46%, respectively. The percentage of the isolated Escherichia coli strains resistant to oxytetracycline, streptomycin and sulfamethoxazole ranged from 49% to 68%; the other agents tested showed lower percentages (0-13%). Resistance to three or more antibiotics was observed in 43% of the isolates. Of the 52 resistance patterns that could be distinguished, 51% was accounted by only four patterns: oxytetracycline+streptomycin+sulfamethoxazole 20%, sulfamethoxazole 12%, streptomycin+sulfamethoxazole 11% and streptomycin+oxytetracycline 8%.