Srinivasan Velusamy, Gillespie Barbara E, Lewis Mark J, Nguyen Lien T, Headrick Susan I, Schukken Ynte H, Oliver Stephen P
Food Safety Center of Excellence and Department of Animal Science, The University of Tennessee, Knoxville, TN 37996, USA.
Vet Microbiol. 2007 Oct 6;124(3-4):319-28. doi: 10.1016/j.vetmic.2007.04.040. Epub 2007 Apr 29.
Pulsed field gel electrophoresis (PFGE) patterns, susceptibility to 26 antimicrobial agents used in veterinary and human medicine, and prevalence of antimicrobial resistance genes of Escherichia coli isolated from cows with mastitis were evaluated. Among 135 E. coli isolates, PFGE analysis revealed 85 different genetic patterns. All E. coli were resistant to two or more antimicrobials in different combinations. Most E. coli were resistant to antimicrobials used in veterinary medicine including ampicillin (98.4%, >or=32 microg/ml) and many E. coli were resistant to streptomycin (40.3%, >or=64 microg/ml), sulfisoxazole (34.1%, >or=512 microg/ml), and tetracycline (24.8%, >or=16 microg/ml). Most E. coli were resistant to antimicrobials used in human medicine including aztreonam (97.7%, >or=32 microg/ml) and cefaclor (89.9%, >or=32 microg/ml). Some E. coli were resistant to nitrofurantoin (38%, >or=128 microg/ml), cefuroxime (22.5%, >or=32 microg/ml), fosfomycin (17.8%, >or=256 microg/ml). All E. coli were susceptible to ciprofloxacin and cinoxacin. Almost 97% (123 of 127) of ampicillin-resistant isolates carried ampC. Eleven of 52 (21.2%) streptomycin-resistant isolates carried strA, strB and aadA together and 29 streptomycin-resistant isolates (55.8%) carried aadA alone. Among 44 sulfisoxazole-resistant E. coli, 1 isolate (2.3%) carried both sulI and sulII, 12 (27.3%) carried sulI and 10 (22.7%) isolates carried sulII. Among 32 tetracycline-resistant isolates, 14 (43.8%) carried both tetA and tetC and 14 (43.8%) carried tetC. Results of this study demonstrated that E. coli from cows with mastitis were genotypically different, multidrug resistant and carried multiple resistance genes. These bacteria can be a reservoir for antimicrobial resistance genes and can play a role in the dissemination of antimicrobial resistance genes to other pathogenic and commensal bacteria in the dairy farm environment.
对从患乳腺炎奶牛分离出的大肠杆菌进行了脉冲场凝胶电泳（PFGE）图谱分析、对兽用和人用的26种抗菌药物的敏感性评估以及抗菌耐药基因的流行情况评估。在135株大肠杆菌分离株中，PFGE分析显示出85种不同的基因图谱。所有大肠杆菌对两种或更多种抗菌药物存在不同组合的耐药性。大多数大肠杆菌对兽用抗菌药物耐药，包括氨苄西林（98.4%，≥32μg/ml），许多大肠杆菌对链霉素（40.3%，≥64μg/ml）、磺胺异恶唑（34.1%，≥512μg/ml）和四环素（24.8%，≥16μg/ml）耐药。大多数大肠杆菌对人用抗菌药物耐药，包括氨曲南（97.7%，≥32μg/ml）和头孢克洛（89.9%，≥32μg/ml）。一些大肠杆菌对呋喃妥因（38%，≥128μg/ml）、头孢呋辛（22.5%，≥32μg/ml）、磷霉素（17.8%，≥256μg/ml）耐药。所有大肠杆菌对环丙沙星和西诺沙星敏感。几乎97%（127株中的123株）氨苄西林耐药分离株携带ampC基因。52株链霉素耐药分离株中有11株（21.2%）同时携带strA、strB和aadA基因，29株链霉素耐药分离株（55.8%）仅携带aadA基因。在44株磺胺异恶唑耐药的大肠杆菌中，1株（2.3%）同时携带sulI和sulII基因，12株（27.3%）携带sulI基因，10株（22.7%）分离株携带sulII基因。在32株四环素耐药分离株中，14株（43.8%）同时携带tetA和tetC基因，14株（43.8%）携带tetC基因。本研究结果表明，患乳腺炎奶牛的大肠杆菌在基因型上存在差异，具有多重耐药性且携带多个耐药基因。这些细菌可能是抗菌耐药基因的储存库，并可能在抗菌耐药基因向奶牛场环境中的其他致病和共生细菌传播中发挥作用。
