Bunner Christine A, Norby Bo, Bartlett Paul C, Erskine Ronald J, Downes Frances P, Kaneene John B
Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824-1324, USA.
J Am Vet Med Assoc. 2007 Jul 15;231(2):275-83. doi: 10.2460/javma.231.2.275.
To determine and compare levels and patterns of antimicrobial resistance among Escherichia coli isolated from pigs on farms that did not use antimicrobial agents versus pigs produced under conventional methods.
Cross-sectional study. Sample Population-35 antimicrobial-free and 60 conventional swine farms.
Farms were visited once, and fecal samples were collected from 15 finisher pigs if available. One E coli isolate from each sample was tested for susceptibility pattern to 14 antimicrobial agents by use of microbroth dilution.
E coli isolates were recovered from 1,381 (97.1%) of 1,422 fecal samples. Herd size was significantly larger for conventional swine farms. Resistance to ceftriaxone, ciprofloxacin, or nalidixic acid was not observed on any of the 95 farms. Three isolates from 2 conventional farms were resistant to ceftiofur. Conventional farms had significantly higher levels of resistance to ampicillin, sulfamethoxazole, tetracycline, and chloramphenicol, compared with antimicrobial-free farms. Fourteen percent of E coli isolates were susceptible or had intermediate resistance to all the tested antimicrobial agents. The 3 most frequent patterns of multiple resistance were streptomycin-tetracycline, sulfamethoxazole-tetracycline, and kanamycin-streptomycin-sulfamethoxazole-tetracycline.
Cessation of antimicrobial use did not appear to result in an immediate reduction in antimicrobial resistance in swine farms. Prospective studies of long-term antimicrobial usage and cessation are needed to estimate the extent to which food animal production may be contributing to antimicrobial drug resistance and might provide a direct measure of the rates of reversibility of antimicrobial drug resistance that might be achieved by curtailing antimicrobial usage.
确定并比较从未使用抗菌药物的猪场中分离出的大肠杆菌与传统方法养殖的猪所分离出的大肠杆菌的耐药水平和模式。
横断面研究。样本群体——35个无抗菌药物猪场和60个传统养猪场。
对猪场进行一次走访，若有15头育肥猪则采集其粪便样本。使用微量肉汤稀释法对每个样本中的一株大肠杆菌分离株进行14种抗菌药物的药敏试验。
从1422份粪便样本中的1381份（97.1%）中分离出了大肠杆菌。传统养猪场的猪群规模显著更大。在95个猪场中均未观察到对头孢曲松、环丙沙星或萘啶酸的耐药情况。来自2个传统猪场的3株分离株对头孢噻呋耐药。与无抗菌药物猪场相比，传统猪场对氨苄西林、磺胺甲恶唑、四环素和氯霉素的耐药水平显著更高。14%的大肠杆菌分离株对所有测试抗菌药物敏感或呈中介耐药。多重耐药最常见的3种模式为链霉素-四环素、磺胺甲恶唑-四环素以及卡那霉素-链霉素-磺胺甲恶唑-四环素。
停止使用抗菌药物似乎并未立即降低猪场中的抗菌药物耐药性。需要对抗菌药物的长期使用和停用进行前瞻性研究，以评估食用动物生产可能导致抗菌药物耐药性的程度，并可能提供一种直接衡量通过减少抗菌药物使用可实现的抗菌药物耐药性逆转率的方法。
