Lee Gi Yong, Yang Soo-Jin
School of Bioresources and Bioscience, Chung-Ang University, Anseong 17546, Korea.
Anim Biosci. 2021 Apr;34(4):734-742. doi: 10.5713/ajas.20.0660. Epub 2021 Jan 1.
The present study aimed to investigate the occurrence and species of coagulasepositive staphylococci (CoPS) and coagulase-negative staphylococci (CoNS) in retail pork meat samples collected during nationwide monitoring. The staphylococcal isolates were characterized for antimicrobial and zinc chloride resistance and enterotoxigenic potential.
A total of 260 pre-packaged pork meat samples were collected from 35 retail markets in 8 provinces in Korea for isolation of staphylococci. Antimicrobial and zinc chloride resistance phenotypes, and genes associated with the resistance phenotypes were determined on the isolates. Furthermore, the presence and distribution of 19 staphylococcal enterotoxin (SE) genes and enterotoxin-like genes among the pork-associated staphylococci were determined by multiplex polymerase chain reaction-based assays using the specific primer sets.
A total of 29 staphylococcal strains (29/260, 11.1%) were isolated from samples of retail pork meat, 24 (83%) of which were CoNS. The four CoNS species identified were S. saprophyticus (n = 16, 55%), S. sciuri (n = 3, 10%), S. warneri (n = 3, 10%), and S. epidermidis (n = 2, 7%). Among the 29 isolates, four methicillin-resistant CoNS (MR-CoNS; three S. sciuri and one S. epidermidis) and one methicillin-resistant CoPS (MR-CoPS; one S. aureus) were identified. In addition, a relatively high level of tetracycline (TET) resistance (52%) was confirmed in CoNS, along with a predominant distribution of tet(K). The most prevalent SEs were sep (45%), and sen (28%), which were carried by 81% of S. saprophyticus.
These findings suggest that CoNS, especially S. saprophyticus strains, in raw pork meat could be a potential risk factor for staphylococcal food poisoning (SFP), and therefore, requires further investigation to elucidate the role of SEls in SFP and virulence of the pathogen. Our results also suggest that CoNS from raw pork meat may act as a source for transmission of antimicrobial resistance genes such as staphylococcal cassette chromosome mec and tet(K).
本研究旨在调查在全国范围内监测期间采集的零售猪肉样本中凝固酶阳性葡萄球菌（CoPS）和凝固酶阴性葡萄球菌（CoNS）的发生情况及种类。对葡萄球菌分离株进行抗微生物和耐氯化锌特性以及产肠毒素潜力的鉴定。
从韩国8个省份的35个零售市场采集了总共260份预包装猪肉样本，用于分离葡萄球菌。测定分离株的抗微生物和耐氯化锌表型以及与这些抗性表型相关的基因。此外，使用特异性引物组通过基于多重聚合酶链反应的检测方法，确定猪肉相关葡萄球菌中19种葡萄球菌肠毒素（SE）基因和类肠毒素基因的存在及分布情况。
从零售猪肉样本中总共分离出29株葡萄球菌（29/260，11.1%），其中24株（83%）为CoNS。鉴定出的4种CoNS菌种分别为腐生葡萄球菌（n = 16，55%）、松鼠葡萄球菌（n = 3，10%）、沃氏葡萄球菌（n = 3，10%）和表皮葡萄球菌（n = 2，7%）。在这29株分离株中，鉴定出4株耐甲氧西林CoNS（MR-CoNS；3株松鼠葡萄球菌和1株表皮葡萄球菌）和1株耐甲氧西林CoPS（MR-CoPS；1株金黄色葡萄球菌）。此外，在CoNS中确认了相对较高水平的四环素（TET）抗性（52%），tet(K)呈优势分布。最常见的SEs是sep（45%）和sen（28%），81%的腐生葡萄球菌携带这些毒素。
这些发现表明，生猪肉中的CoNS，尤其是腐生葡萄球菌菌株，可能是葡萄球菌食物中毒（SFP）的潜在风险因素，因此，需要进一步研究以阐明SEls在SFP中的作用以及该病原体的毒力。我们的结果还表明，生猪肉中的CoNS可能作为抗微生物抗性基因（如葡萄球菌盒式染色体mec和tet(K)）传播的来源。
