Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Länggass-Strasse 122, CH-3012 Bern, Switzerland.
BMC Vet Res. 2011 Jun 24;7:30. doi: 10.1186/1746-6148-7-30.
In years past, methicillin-resistant S. aureus (MRSA) has been frequently detected in pigs in Europe, North America and Asia. Recent, yet sporadic studies have revealed a low occurrence of MRSA in Switzerland. In 2009, a monitoring survey of the prevalence and genetic diversity of methicillin-resistant S. aureus (MRSA) in slaughter pigs in Switzerland was conducted using methods recommended by the EU guidelines, and using a sampling strategy evenly distributed throughout the year and representative of the Swiss slaughter pig population. Monitoring should determine if the overall prevalence of MRSA in the entire country is increasing over the years and if specific multi-resistant MRSA clones are spreading over the country.
In 2009, the nasal cavities of eight out of 405 randomly selected pigs were positive for MRSA, representing a prevalence of 2.0% (95% CI 0.9-3.9). The following year, 23 out of 392 pigs were positive for MRSA [5.9% prevalence (95% CI 3.8-8.7)]. Three multilocus sequence types (ST), four spa types and two types of staphylococcal cassette chromosome mec (SCCmec) elements were detected. The most frequent genotypes were ST398 (MLST)-(spa)t034-V(SCCmec) (n=18) and ST49-t208-V (n=7), followed by ST398-t011-V (n=4), ST398-t1451-V (n=1), and ST1-t2279-IVc (n=1). The isolates displayed resistance to ß-lactams [mecA, (31/31); blaZ, (19/31)]; tetracycline [tet(M), (31/31); tet(K), (30/31)] (n=31); macrolides and lincosamides [erm(C) (4/31) or erm(A) (18/31)] (n=22); tiamulin [vga(A)v (9/31) or unknown mechanism (18/31)] (n=27); trimethoprim [dfr(G) (18/31); spectinomycin [ant(9)-Ia (19/31) or unknown mechanism (3/31)] (n=22); streptomycin [str (19/31)]; sulphamethoxazole (7/31) and ciprofloxacin (n=1) (mechanisms not determined).
This study is the first to describe the presence of MRSA ST49 in slaughter pigs, and to demonstrate a significant and nearly three-fold increase of MRSA prevalence in pigs within two years. The presence of a specific clonal lineage of MRSA from Switzerland suggests that it has been selected in Swiss pig husbandry. Effective hygiene measures should be enhanced within the entire pig production chain to suppress the spread of these pathogens into the community.
过去几年中，耐甲氧西林金黄色葡萄球菌（MRSA）在欧洲、北美和亚洲的猪群中经常被检测到。最近，尽管研究较为零散，但仍显示瑞士 MRSA 的发生率较低。2009 年，采用欧盟指南推荐的方法，并采用全年均匀分布且代表瑞士屠宰猪群的抽样策略，对瑞士屠宰猪中耐甲氧西林金黄色葡萄球菌（MRSA）的流行率和遗传多样性进行了监测调查。监测应确定该国整体 MRSA 流行率是否逐年增加，以及是否有特定的多耐药 MRSA 克隆在全国范围内传播。
2009 年，从 405 只随机选择的猪中，有 8 只鼻腔拭子的 MRSA 呈阳性，阳性率为 2.0%（95%CI 0.9-3.9）。次年，392 只猪中有 23 只 MRSA 呈阳性[5.9%的流行率（95%CI 3.8-8.7）]。检测到 3 种多位点序列类型（ST）、4 种 spa 型和 2 种葡萄球菌盒式染色体 mec（SCCmec）元件。最常见的基因型是 ST398（MLST）-（spa）t034-V（SCCmec）（n=18）和 ST49-t208-V（n=7），其次是 ST398-t011-V（n=4），ST398-t1451-V（n=1）和 ST1-t2279-IVc（n=1）。分离株对β-内酰胺类药物[mecA，（31/31）；blaZ，（19/31）]具有耐药性；四环素[tet（M），（31/31）；tet（K），（30/31）]（n=31）；大环内酯类和林可酰胺类[erm（C）（4/31）或 erm（A）（18/31）]（n=22）；泰妙菌素[vga（A）v（9/31）或未知机制（18/31）]（n=27）；甲氧苄啶[dfr（G）（18/31）；大观霉素[ant（9）-Ia（19/31）或未知机制（3/31）]（n=22）；链霉素[str（19/31）]；磺胺甲恶唑（7/31）和环丙沙星（n=1）（机制未确定）。
这项研究首次描述了耐甲氧西林金黄色葡萄球菌 ST49 在屠宰猪中的存在，并表明在两年内猪中耐甲氧西林金黄色葡萄球菌的流行率显著增加了近三倍。瑞士耐甲氧西林金黄色葡萄球菌特定克隆谱系的存在表明，它已在瑞士养猪业中得到选择。应在整个养猪生产链中加强有效的卫生措施，以抑制这些病原体传播到社区。
