Changes in antimicrobial susceptibility in a population of Escherichia coli isolated from feedlot cattle administered ceftiofur crystalline-free acid
Changes in antimicrobial susceptibility in a population of Escherichia coli isolated from feedlot cattle administered ceftiofur crystalline-free acid
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DOI：
10.2460/ajvr.68.5.501
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发表时间：
2007-05-01
影响因子：
1
通讯作者：
Brashears, Mindy M.
中科院分区：
文献类型：
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作者：
Lowrance, T. Courtney;Loneragan, Guy H.;Brashears, Mindy M.
目的 - 确定施用头孢噻呋无结晶酸 (CCFA) 对饲养场牛大肠杆菌抗菌敏感性的影响。动物 - 61 头饲养场公牛。程序 - 进行了一项队列研究。公牛圈养在围栏中（5 个围栏内有 10 头小牛，1 个围栏内有 11 头小牛）。每个栏内的 5 头公牛接受 CCFA，其中 5 头作为对照公牛（1 栏有 6 头对照公牛）。 CCFA给药包括单剂量方案（6.6 mg/kg，SC，第0天）、三分之二剂量方案（4.4 mg/kg，SC，第0天）和3剂量方案（6.6 mg/kg，SC，第0、6和13天）。在第0、2、6、9、13、16、20和28天收集粪便样本。在施用CCFA之前立即收集粪便样本。针对 3 株大肠杆菌分离株/粪便样本测定了 15 种抗菌剂的最低抑菌浓度。通过使用直接平板技术对大肠杆菌进行计数。结果 - 在回收的 1,441 株分离株中，有 986 株 (68.4%) 检测到对 1 种或多种抗菌药物具有耐药性。 CCFA 的施用与头孢噻呋耐药菌株数量的短暂增加有关。在CCFA施用完成后大约2周，敏感性返回到第0天的值（在CCFA施用之前立即收集的样品）。头孢噻呋耐药性和对氨苄青霉素、氯霉素、链霉素、磺胺异恶唑和四环素的共耐药性之间的一致性几乎是完美的（kappa，0.97）。我们没有检测到从混合对照阉牛中回收的大肠杆菌的敏感性变化。结论和临床相关性 - CCFA 的施用提供了有利于多重耐药变体短暂扩张的选择压力。
Objective - To determine effects of administration of ceftiofur crystal line-free acid (CCFA) on antimicrobial susceptibility of Escherichia coli in feedlot cattle. Animals - 61 feedlot steers. Procedures - A cohort study was conducted. Steers were housed in pens (5 pens with 10 steers and 1 pen with 11 steers). Five steers in each pen were administered CCFA, and 5 served as control steers (1 pen had 6 control steers). The CCFA administration included a single-dose regimen (6.6 mg/kg, SC, on day 0), two-thirds-dose regimen (4.4 mg/kg, SC, on day 0), and 3-dose regimen (6.6 mg/kg, SC, on days 0, 6, and 13). Fecal samples were collected on days 0, 2, 6, 9, 13, 16, 20, and 28. Fecal samples were collected immediately before CCFA administration. Minimum inhibitory concentrations of 15 antimicrobials were determined for 3 E coli isolates/fecal sample. Escherichia coli were enumerated by use of direct-plating techniques. Results - Resistance to 1 or more antimicrobials was detected in 986 of 1,441 (68.4%) isolates recovered. Administration of CCFA was associated with a transient increase in the population of ceftiofur-resistant isolates. Susceptibility returned to day 0 values lie, samples collected immediately before CCFA administration) approximately 2 weeks after completion of CCFA administration. Agreement between ceftiofur resistance and coresistance to ampicillin, chloramphenicol, streptomycin, sulfisoxazole, and tetracycline was almost perfect (kappa, 0.97). We did not detect variation in susceptibility of E coli recovered from commingled control steers. Conclusions and Clinical Relevance - Administration of CCFA provided selection pressure that favored transient expansion of multiple-resistant variants.