Antibiotic susceptibility pattern of Escherichia coli strains with verocytotoxic E-coli-associated virulence factors from food and animal faeces

There is limited information available on the antibiotic susceptibility patterns of enterohemorrhagic Escherichia coli (EHEC) or Verocytotoxin-producing E. coli (VTEC). Therefore in vitro antibiotic activities of 13 antibiotic substances against 60 E. coli isolates (from food or animal and one human faecal isolate) with VTEC-associated virulence factors were determined. The isolates harboured at least one of the following virulence factors: vtx1 and/or vtx2 gene, eae gene (EHEC or EPEC) or EHEC hly A gene. There was no relationship between serotype, virulence factor and resistance pattern. All strains were susceptible to quinolones, gentamicin. trimethoprim/sulfamethoxazole and nitrofurantoin. Resistant isolates were observed for cephalothin, tetracycline and in one case for cefazolin. Minimal inhibition concentrations at which 90% of the strains were inhibited were 8mugml(-1) for ampicillin, 8/4mug ml(-1) for ampicillin/sulbactam, > 16 mugml(-1) for cephalothin, 8mug ml(-1) for tetracycline and 8mugml(-1) for chloramphenicol. No multi-drug-resistance was observed. Cephalothin and tetracycline show the potential for an increased resistance rate as a high number of isolates was intermediate resistant. The resistance profile of E. coli with VTEC-AVF investigated in this study reveals a high percentage of susceptible isolates compared to E. coli isolates in general and is similar to profiles published for EHEC or VTEC strains. (C) 2002 Elsevier Science Ltd. All rights reserved.