Departamento de Agricultura y Alimentación, Universidad de La Rioja, Logroño, Spain.
Departamento de Agricultura y Alimentación, Universidad de La Rioja, Logroño, Spain.
Int J Food Microbiol. 2020 May 2;320:108510. doi: 10.1016/j.ijfoodmicro.2020.108510. Epub 2020 Jan 8.
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.
耐甲氧西林金黄色葡萄球菌（MRSA）CC398 是一种与家畜相关（LA）的谱系，主要在猪中检测到。其通过食物链传播可能是食品安全问题。本研究旨在研究猪肉制品中金黄色葡萄球菌谱系的多样性，确定 CC398 谱系的 MRSA 和甲氧西林敏感金黄色葡萄球菌（MSSA）的流行情况，并研究回收分离株的抗菌药物耐药表型/基因型和毒力特征。在西班牙北部采集了 101 份猪源食品样本用于金黄色葡萄球菌分离。分析了抗生素耐药谱，并通过 PCR 筛选相关耐药基因。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。猪源食品中金黄色葡萄球菌和 MRSA 的检出率分别为 33.6%和 21.8%。从 39 株金黄色葡萄球菌分离株中鉴定出 19 种 spa 型和 12 种 ST 型，ST398 为主要谱系（n=25；64%）。MRSA-CC398 分离株（n=23）主要为 spa-t011（n=16），82.6%为多药耐药（MDR）。所有 MRSA-CC398 分离株均对四环素耐药且 IEC 阴性，其中 4 株携带 eta、tst 或 sea 基因。检测到的 2 株 MSSA-CC398 分离株为 spa-t5452，IEC 阳性，对青霉素（blaZ）和红霉素/克林霉素（诱导型）（ermT 有/无 ermC+msrA）耐药。在 14 株非 CC398 分离株中，只有 2 株为 MRSA（ST8，PVL 阳性，肠毒素阳性，IEC 阴性）。12 株 MSSA 分离株包括 2 株 CC45 谱系，IEC 阳性。CC398 谱系在猪源食品中的金黄色葡萄球菌中较为流行（MRSA 和 MSSA 均有），LA-MRSA-CC398/t011 是最主要的克隆。食品中存在 IEC 阳性 MSSA-CC398 和 MSSA-CC45 分离株，这突显了从业人员在食源性病原体传播中的潜在作用。此外，鉴于检测到的多药耐药分离株和毒力基因的高频率，应改善卫生实践，以限制金黄色葡萄球菌通过食物链的传播风险。
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