Survey of Shiga toxigenic Escherichia coli O157 and drug-resistant coliform bacteria from in-line milk filters on dairy farms in the Czech Republic

Abstract

To determine the occurrence of Shiga toxin-producing Escherichia coli (STEC) O157 and coliform bacteria isolates resistant to antimicrobial agents in dairy herds by examining milk filters and to analyse the influence of management factors and antibiotic use on antimicrobial resistance. A total of 192 in-line milk filters were sampled on 192 dairy farms in the Czech Republic. Information on feeding, husbandry, production, and antibiotic therapy were obtained by questionnaire. The milk filters were cultured for STEC O157 and coliform bacteria. All recovered isolates were examined for antimicrobial susceptibility and presence of antimicrobial-resistance genes. STEC O157 was detected in four (2%) of the filters. Resistant nonpathogenic E. coli and coliform bacteria isolates with specific genes were detected in 44 (23%) of the filters. The study demonstrated a high prevalence of resistant coliform bacteria in milk filters obtained on Czech dairy farms. The occurrence of resistant coliform bacteria in milk filters was significantly higher among isolates from farms where antibiotic therapy against mastitis was employed during the dry period (P < 0.05).