engleski

Antimicrobial resistance of beta-hemolytic Escherichia coli associated with diarrhea in weaned pigs from large pig breeding farms in Croatia

Bacterial isolates from dead pig organs were collected from 9 large pig breeding farms in Croatia during 2003. All E. coli isolates (n=63) were obtained from weaned piglets that died with clinical signs of diarrhea. The hemolytic strains containing F4, F6 and F18 fimbriae were included. Fimbriae were determined by the method of the coagglutination using home-made sera. The antimicrobal sensitivity test was done by the ATB VET strips (API, bioMerieux, France) in a semi solid medium similar to the reference method (agar dilution method). Beta-hemolytic E. coli is the most common bacterial etiologic agent of diarrhea in neonatal and postweaning pigs. Treatment of enteric E. coli infections in swine commonly includes the use of broad-spectrum antibiotics. The smallest rate of susceptibility was recorded towards tetracycline (0%), doxycycline (10 %) streptomycin (14%) and sulfamethazole (24 %) / Multidrug resistance was frequently observed, with 87% of E. coli isolates resistant to 4 or more antibiotics. The swine E. coli isolates showed a pattern similar to other clinical veterinary E. coli strains in terms of their increased resistance to tetracycline, streptomycin, sulfamethoxazole/trimethoprim and gentamicin. A steady decrease has been observed in the sensitivity towards enrofloxacin, as only 76% of the strains were sensitive to this drug. The studies conducted in Croatia in 1990 revealed no E. coli strains resistant to enrofloxacin. The high rate of sensitivity to colistin (95%) and cefoperazon (100 %) are attributed to the fact that colistin and cefoperazon have not been used in veterinary medicine in Croatia until today, and a more common use of colistin in intensive pig breeding may result in an increased resistance to this antimicrobial in the future. Although a ban has been placed on the systemic use of cloramphenicol in Croatia for more than 10 years now, 76% of the investigated isolates were resistant to this antibiotic.

Antimicrobial resistance; Escherichia coli; pigs

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