Major diseases, extensive misuse, and high antimicrobial resistance of Escherichia coli in large- and small-scale dairy cattle farms in Jordan.

This study aimed to determine the major diseases, antimicrobial use, and resistance in commensal Escherichia coli in dairy cattle in Jordan. Forty-three (large, n = 21; small, n = 22) farms were surveyed. A validated questionnaire was administered to the herdsmen to elicit information about disease prevalence, antimicrobial knowledge, and antimicrobial use. In addition, fecal samples were collected from 5 lactating animals on each farm. A total of 520 E. coli isolates were tested for resistance to 12 antimicrobials. From the herdsmen's perspective, the diseases that require use of veterinary services in large and small production systems were mastitis (51.2%), metritis (51.2%), and enteritis (39.5%), and the most commonly used antimicrobials were oxytetracycline and streptomycin. Dairy herdsmen (83.7%) reported that it is easy to purchase antimicrobials without a veterinary prescription and 97.7% of them more frequently changed the antimicrobial drug rather than increasing the dose when presented with nonresponse to treatment. Escherichia coli isolates exhibited high resistance to streptomycin (47.5%), tetracycline (45.4%), and ampicillin (34.2%). Less than 10% of isolates were resistant to chloramphenicol, kanamycin, gentamicin, ciprofloxacin, and ceftriaxone. Overall, 64.6 and 37.1% of the E. coli isolates exhibited resistance to ≥1 antimicrobial and multidrug resistance (resistance to ≥3 antimicrobial classes), respectively. The isolates exhibited 107 antimicrobial resistance profiles. This study indicates that antimicrobials are frequently misused in dairies in Jordan and that resistance among commensal E. coli toward antimicrobials of human and veterinary importance is high. Therefore, educational programs for herdsmen and enacting regulations and guidelines are necessary to promote the judicious use of antimicrobials in dairy animals in Jordan.