Antimicrobial susceptibility of enterotoxigenic strains of Escherichia coli isolated from weaned pigs in Croatia

The E-test method was employed to assess the sensitivity of 114 Escherichia coli, isolates to 10 antimicrobials. All E. coli isolates were obtained from weaned piglets that died with clinical signs of diarrhea. E. coli isolates showed highest rate of resistance to oxytetracycline, streptomycin and sulphametoxazole/trimethoprim (89%, 74% and 50% of isolates, respectively), whereas 68% of the isolates were resistant to 4 or more antimicrobials. The high sensitivity rate of (97 %) to colistin is attributed to the fact that colistin has been used in veterinary medicine in Croatia only last 2-3 years. All strains were sensitive to cefotaxime. The high multidrug resistance of E. coli strains isolated from large swine agglomerations most probably was due to the obsolete farming technology where economically profitable productivity could hardly be maintained without the systemic use of antibiotics administered in the critical steps of production.