Laboratory of Analytical Biochemistry and Biotechnology, University of Mouloud Mammeri, Tizi Ouzou, Algeria.
Biochemistry and Molecular Biology, University of La Rioja, Logrono, Spain.
J Appl Microbiol. 2020 Oct;129(4):1043-1052. doi: 10.1111/jam.14665. Epub 2020 May 12.
The aim of this study was to characterize Staphylococcusaureus isolates of food origin (dairy and meat products, pastries and sandwiches) determining the carriage in enterotoxin genes and the antimicrobial resistance pheno/genotypes.
A total of 300 food samples were collected and analysed for the detection of S. aureus. The presence of enterotoxin genes was investigated by multiplex PCRs. Resistance of isolates to 11 antimicrobials was determined using disc diffusion method and molecular characterization of methicillin-resistant S. aureus was carried out by spa typing and multilocus sequence typing. Overall, 51 out of 300 samples (17%) were contaminated with S. aureus, and 104 isolates were recovered. In all, 65 of these isolates (62·5%) harboured one or more genes encoding for staphylococcal enterotoxins, being seg and sei the most observed genes. The highest resistance profile was ascribed to penicillin G (95·19%). Five isolates were methicillin-resistant (MRSA) harbouring the mecA gene. All MRSA isolates belonged to the sequence type ST5 and to two different spa types (t450 and t688); the MRSA-t450 isolate carried the scn gene (specific marker of the immune evasion cluster system), but the four MRSA-t688 isolates were scn negative. The MRSA isolates carried enterotoxin genes but were negative for the genes of the Panton Valentine leukocidine (lukF/S-PV).
The presence of enterotoxigenic S. aureus isolates, including MRSA, in food samples can represent a risk for public health.
This work describes the molecular characteristics of MRSA strains isolated from foods in Algeria and it can contribute to an extended database concerning the S. aureus isolated from food origin.
本研究旨在对食品（乳制品和肉类产品、糕点和三明治）来源的金黄色葡萄球菌（Staphylococcus aureus）分离株进行特征描述，确定其肠毒素基因的携带情况，并分析其抗微生物药物耐药表型/基因型。
共采集 300 份食品样本进行金黄色葡萄球菌检测。采用多重 PCR 方法检测肠毒素基因的存在。采用纸片扩散法检测分离株对 11 种抗生素的耐药性，并通过 spa 分型和多位点序列分型对耐甲氧西林金黄色葡萄球菌（methicillin-resistant S. aureus，MRSA）进行分子特征分析。结果显示，300 份样本中有 51 份（17%）受到金黄色葡萄球菌污染，共回收 104 株分离株。所有分离株中，65 株（62.5%）携带一种或多种编码葡萄球菌肠毒素的基因，其中 seg 和 sei 基因最为常见。青霉素 G 的耐药率最高（95.19%）。5 株分离株为耐甲氧西林金黄色葡萄球菌，均携带 mecA 基因。所有耐甲氧西林金黄色葡萄球菌分离株均属于 ST5 序列型，且 spa 型分别为 t450 和 t688；耐甲氧西林金黄色葡萄球菌-t450 分离株携带 scn 基因（免疫逃逸群系统的特异性标记），而 4 株耐甲氧西林金黄色葡萄球菌-t688 分离株 scn 基因阴性。耐甲氧西林金黄色葡萄球菌分离株携带肠毒素基因，但对 Panton Valentine 白细胞毒素（lukF/S-PV）基因呈阴性。
食品中存在产肠毒素金黄色葡萄球菌（包括耐甲氧西林金黄色葡萄球菌）可能对公共健康构成威胁。
本研究描述了从阿尔及利亚食品中分离的耐甲氧西林金黄色葡萄球菌菌株的分子特征，为食品来源的金黄色葡萄球菌的扩展数据库提供了参考。
