Research Group for Microbial Genomics and Antimicrobial Resistance, National Food Institute, Technical University of Denmark, Kemitorvet Build. 204, DK-2800 Lyngby, Denmark.
Vet Microbiol. 2012 May 25;157(1-2):246-50. doi: 10.1016/j.vetmic.2011.12.023. Epub 2011 Dec 24.
Methicillin-resistant Staphylococcus aureus (MRSA), especially CC398, have emerged in livestock worldwide. We investigated the occurrence of MRSA in pigs at slaughter and in retail meat. During 2009, nasal swabs (n=789) were taken from pigs at slaughter. Moreover, 866 meat samples [Danish: pork (153), broiler meat (121), beef (142) and; imported: pork (173), broiler meat (193), and beef (84)] were randomly collected in retail stores and outlets. MRSA was isolated from nasal swabs or from meat samples after preenrichment (Mueller Hinton broth with 6.5% NaCl), selective enrichment (tryptone soya broth with 4 mg/L cefoxitine and 75 mg/L aztreonam) and selective plating on Brilliance Chromogenic MRSA agar. The presence of mecA was confirmed by PCR and the MRSA isolates were spa typed. Novel MRSA spa types were characterized by MLST, PFGE and SCCmec typing. Thirteen percent (101/789) of the pigs had MRSA. Based on spa types 93% corresponded to CC398 (spa t011, t034, t1451, t2876, t2974), 4% to CC30 (t1333) and one isolate to CC1 (t0127). The spa type t1333 (CC30), which is common among methicillin susceptible S. aureus (MSSA) from pigs in Denmark, contained a SCCmec cassette type V and czrC zinc resistance gene. Imported broiler meat had the highest occurrence (18%) of MRSA, followed by imported pork (7.5%) and Danish pork (4.6%). MRSA ST398 was found for the first time in Danish beef (1.4%). The finding of MRSA CC30 (spa t1333) suggest possible spread of the SCCmec cassette normally associated with ST398 into another S. aureus lineage common in pigs.
耐甲氧西林金黄色葡萄球菌（MRSA），尤其是 CC398，已在全球范围内的牲畜中出现。我们调查了屠宰场猪和零售肉中的 MRSA 发生情况。2009 年期间，从屠宰场的猪身上采集了鼻腔拭子（n=789）。此外，在零售店和销售点随机采集了 866 份肉样[丹麦：猪肉（153）、肉鸡肉（121）、牛肉（142）和进口：猪肉（173）、肉鸡肉（193）和牛肉（84）]。从鼻腔拭子或经过预增菌（含 6.5%NaCl 的 Mueller Hinton 肉汤）、选择性增菌（含 4mg/L 头孢西丁和 75mg/L 氨曲南的胰蛋白胨大豆肉汤）和选择性平板培养（Brilliance 显色性 MRSA 琼脂）后的肉样中分离出 MRSA。通过 PCR 确认 mecA 的存在，并对 MRSA 分离株进行 spa 分型。新型 MRSA spa 型通过 MLST、PFGE 和 SCCmec 分型进行特征描述。13%（101/789）的猪携带 MRSA。根据 spa 型，93%与 CC398 相对应（spa t011、t034、t1451、t2876、t2974），4%与 CC30 相对应（t1333），1 株与 CC1 相对应（t0127）。spa 型 t1333（CC30）在丹麦猪源耐甲氧西林金黄色葡萄球菌（MSSA）中很常见，含有 SCCmec 盒型 V 和 czrC 锌抗性基因。进口肉鸡肉的 MRSA 发生率最高（18%），其次是进口猪肉（7.5%）和丹麦猪肉（4.6%）。首次在丹麦牛肉中发现了 MRSA ST398（1.4%）。CC30（spa t1333）的发现表明，通常与 ST398 相关的 SCCmec 盒可能在另一种常见于猪的金黄色葡萄球菌谱系中传播。
