Methicillin-resistant Staphylococcus aureus (MRSA) CC398 is a livestock-associated (LA) lineage, mainly detected in swine. Its dissemination via the food-chain could be a food-safety issue. This work aimed to study the diversity of S. aureus lineages in pork-products, to determine the prevalence of MRSA and methicillin-susceptible S. aureus (MSSA) of lineage CC398, and to study the antimicrobial resistance phenotype/genotype and the virulence traits of recovered isolates. One hundred and one samples of pig-derived food were collected in Northern Spain for S. aureus isolation. Antibiotic resistance profile was analysed, and associated resistance genes were screened by PCR. Detection of CC398 lineage, spa-type, multilocus sequence-type, virulence factors, immune evasion cluster (IEC) genes, and phage ΦSa3 integrase was performed by PCR/sequencing. The prevalence of S. aureus and MRSA among pig-derived food was 33.6% and 21.8%, respectively. Thirty-nine S. aureus isolates were recovered and attributed to 19 spa-types and 12 STs, ST398 being the predominant lineage (n = 25; 64%). MRSA-CC398 isolates (n = 23) were mainly spa-t011 (n = 16) and 82.6% were multidrug-resistant (MDR). All MRSA-CC398 were tetracycline-resistant and IEC-negative and four hosted either eta, tst or sea gene. The two MSSA-CC398 isolates detected were spa-t5452, IEC-positive, and were resistant to penicillin (blaZ) and erythromycin/clindamycin (inducible) (ermT with/without ermC + msrA). Among the 14 non-CC398 isolates, only two were MRSA (ST8, PVL-positive, enterotoxin-positive, IEC-negative). The 12 MSSA isolates included two of lineage CC45 and IEC-positive. CC398 lineage is prevalent among S. aureus of pig-derived food (both MRSA and MSSA), LA-MRSA-CC398/t011 being the clone most represented. The presence of the IEC-positive MSSA-CC398 and MSSA-CC45 isolates in food products highlights the potential implication of handlers in transmission of foodborne pathogens. Moreover, given the high frequency of MDR isolates and virulence genes detected, hygienic practices should be improved to limit the dissemination risk of S. aureus via the food chain.

中文翻译：

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西班牙猪源食品中非耐药性金黄色葡萄球菌-CC398的高患病率和肠毒素基因的频繁检测。

耐甲氧西林金黄色葡萄球菌（MRSA）CC398是与牲畜相关（LA）的谱系，主要在猪中检出。通过食物链进行传播可能是一个食品安全问题。这项工作旨在研究猪肉产品中金黄色葡萄球菌谱系的多样性，确定谱系CC398的MRSA和甲氧西林敏感金黄色葡萄球菌（MSSA）的患病率，并研究抗药性表型/基因型和毒力特性回收的分离株。在西班牙北部收集了一百零一猪源食品样本用于金黄色葡萄球菌分离。分析抗生素抗性概况，并通过PCR筛选相关的抗性基因。通过PCR /测序检测CC398谱系，spa型，多位点序列型，毒力因子，免疫逃逸簇（IEC）基因和噬菌体ΦSa3整合酶。猪源性食物中金黄色葡萄球菌和MRSA的患病率分别为33.6％和21.8％。回收了39株金黄色葡萄球菌，归因于19种水疗类型和12种ST，ST398是主要谱系（n = 25； 64％）。MRSA-CC398分离株（n = 23）主要是spa-t011（n = 16），82.6％是耐多药（MDR）。所有的MRSA-CC398都具有四环素抗性和IEC阴性，并且有四个宿主eta，tst或sea基因。检测到的两个MSSA-CC398分离株是spa-t5452，IEC阳性，并且对青霉素（blaZ）和红霉素/克林霉素（诱导型）（带有/不带有ermC + msrA的ermT）具有抗性。在14个非CC398分离株中，只有两个是MRSA（ST8，PVL阳性，肠毒素阳性，IEC阴性）。12个MSSA分离株包括两个谱系CC45和IEC阳性。CC398谱系在S中普遍存在。猪源食品的金黄色葡萄球菌（MRSA和MSSA），其中LA-MRSA-CC398 / t011是最具代表性的克隆。食品中IEC阳性的MSSA-CC398和MSSA-CC45分离株的存在突出了处理人员在食源性病原体传播中的潜在影响。此外，鉴于检出的耐多药分离株和致病基因频率很高，应改善卫生习惯，以限制金黄色葡萄球菌通过食物链传播的风险。