Prevalence, molecular characterization, and antimicrobial resistance profiles of Listeria monocytogenes, Salmonella enterica, and Escherichia coli O157:H7 on dairy cattle farms in Jordan

摘要

This study determined the prevalence, pulsed-fieldgel electrophoresis profiles, and antimicrobial resistanceprofile of Listeria monocytogenes, Salmonellaenterica, and Escherichia coli O157:H7 isolates fromdairy cattle farms in Jordan. Samples from bulk tankmilk (n = 305), cattle feces (n = 610), and rectoanalmucosal swabs (n = 610) were collected from 61 dairycattle farms. We confirmed 32 L. monocytogenes, 28S. enterica, and 24 E. coli O157:H7 isolates from thesamples. The farm-level prevalence (at least 1 positivesample per farm) of L. monocytogenes, S. enterica, andE. coli O157:H7 was 27.9, 19.7, and 23.0%, respectively.The prevalence of L. monocytogenes, S. enterica, and E.coli O157:H7 in bulk tank milk was 7.5, 1.6, and 3.3%,respectively. The prevalence of L. monocytogenes and S.enterica in fecal samples was 1.5 and 3.8%, respectively,and the prevalence of E. coli O157:H7 in rectoanal mucosalswabs was 2.3%. Based on disk diffusion testing,all L. monocytogenes, S. enterica, and E. coli O157:H7isolates exhibited resistance to at least 1 antimicrobialclass. Multidrug resistance (resistance to 3 or moreclasses of antimicrobials) was exhibited by 96.9% of L.monocytogenes, 91.7% of E. coli O157:H7, and 82.1% ofS. enterica isolates. Moreover, 93.8, 79.2, and 57.1% ofthe L. monocytogenes, E. coli O157:H7, and S. entericaisolates, respectively, were resistant to 5 or more antimicrobialclasses. More than 50% of L. monocytogenesisolates were resistant to ampicillin, clindamycin, penicillin,erythromycin, quinupristin–dalfopristin, streptomycin,teicoplanin, linezolid, vancomycin, kanamycin,and tetracycline. More than 50% of S. enterica and E.coli O157:H7 isolates were resistant to ampicillin, cephalothin,nalidixic acid, kanamycin, streptomycin, amoxicillin–clavulanic acid, and tetracycline. The prevalenceof the studied pathogens this study was comparable toreports from other countries. The isolated pathogensexhibited a high degree of antimicrobial resistance, suggestingthat the bacterial flora of dairy cattle in Jordanare under intense antimicrobial selection pressure. Additionalresearch is required to determine the causesand drivers of resistance, and to develop approaches tomitigating antimicrobial resistance.