Quantitative Veterinary Epidemiology Group, Wageningen Institute of Animal Sciences, Wageningen University, P.O. Box 338, 6700 AH Wageningen, The Netherlands.
Prev Vet Med. 2011 Feb 1;98(2-3):182-9. doi: 10.1016/j.prevetmed.2010.10.010. Epub 2010 Nov 13.
In 2005, a distinct clone of methicillin resistant Staphylococcus aureus (MRSA CC398) was found in pigs and people in contact with pigs. The structure of the pig production chain in high technology pig husbandry enables pathogens to spread during animal trading, with an increasing prevalence in herds further down the chain. The objective of this study was to quantify the effect of the MRSA status of the supplying herd on the MRSA status of the receiving herd in order to gain more insight into the role of animal trading as a transmission route for MRSA CC398. Nasal samples (60-80 pigs per herd) were collected from 38 herds; in 20 herds, environmental samples were collected as well. Ten MRSA-positive herds (based on the results of nasal swabs of 10 individual pigs per herd) from a prior study were included in the data analysis. Herds were classified as MRSA positive if at least one sample tested positive. The 48 herds were part of 14 complete (40 herds) and 4 incomplete (8 herds) pig production chains. Fifty-six percent of the herds were classified as MRSA positive. MRSA-positive herds were observed at the start (breeding herds), middle (farrowing herds) and the end (finishing herds) of the pig production chain. All of the herds in 8 chains tested MRSA positive;, all of the herds in 5 chains tested MRSA negative and in the remaining 5 chains, MRSA-positive and MRSA-negative herds were detected. Seven spa types were found, which were all previously confirmed to belong to CC398. All of the isolates were susceptible to mupirocin, linezolid, rifampicin, fusidic acid and cotrimoxazole. Resistance against tetracycline, erythromycin and clindamycin was found in 100, 74 and 76% of the isolates, respectively. Seventy-nine percent of herds with a MRSA-positive supplier of pigs were MRSA positive, whereas 23% of herds with a MRSA-negative supplier were MRSA positive (OR=10.8; 95% CI: 1.5-110.1; P=0.011). The presence of entirely MRSA-positive and MRSA-negative chains and the strong association between the MRSA status of herds and their suppliers illustrates a large risk associated with purchasing pigs from MRSA-positive herds; a top-down strategy for future control programs is, therefore, a basic requirement. However, 23% of herds with a MRSA-negative supplier were MRSA positive and furthermore, 46% of the herds at the top of the pig production chain without a supplier tested MRSA positive. This underlined the need for the identification of additional risk factors for MRSA.
2005 年，在接触猪的人和猪身上发现了一种独特的耐甲氧西林金黄色葡萄球菌（MRSA CC398）克隆。高科技养猪业中的猪生产链结构使得病原体在动物交易过程中传播，并且在生产链下游的畜群中越来越普遍。本研究的目的是量化供体畜群的 MRSA 状态对受体畜群的 MRSA 状态的影响，以便更深入地了解动物交易作为 MRSA CC398 传播途径的作用。从 38 个畜群中采集了 60-80 头猪的鼻腔样本；在 20 个畜群中还采集了环境样本。对先前研究中 10 个 MRSA 阳性畜群（基于每个畜群 10 头猪的鼻腔拭子结果）进行了数据分析。如果至少有一个样本检测呈阳性，则将畜群归类为 MRSA 阳性。这 48 个畜群是 14 个完整（40 个畜群）和 4 个不完整（8 个畜群）猪生产链的一部分。56%的畜群被归类为 MRSA 阳性。在猪生产链的开始（繁殖畜群）、中间（分娩畜群）和结束（育肥畜群）都观察到了 MRSA 阳性畜群。8 个链条中的所有畜群均检测到 MRSA 阳性；5 个链条中的所有畜群均检测到 MRSA 阴性，而在其余 5 个链条中，则检测到 MRSA 阳性和阴性畜群。发现了 7 种 spa 型，均经证实属于 CC398。所有分离株均对莫匹罗星、利奈唑胺、利福平、夫西地酸和复方磺胺甲噁唑敏感。100%、74%和 76%的分离株分别对四环素、红霉素和克林霉素耐药。79%的 MRSA 阳性猪供应畜群为 MRSA 阳性，而 23%的 MRSA 阴性猪供应畜群为 MRSA 阳性（OR=10.8；95%CI：1.5-110.1；P=0.011）。完全 MRSA 阳性和阴性链条的存在以及畜群与供应商之间的 MRSA 状态之间的强烈关联表明，从 MRSA 阳性畜群购买猪存在很大风险；因此，未来控制计划的自上而下策略是基本要求。然而，23%的 MRSA 阴性供应畜群为 MRSA 阳性，此外，在没有供应商的猪生产链顶端的 46%的畜群检测到 MRSA 阳性。这强调了确定其他 MRSA 风险因素的必要性。
