Rong Dongli, Liu Zhenjie, Huang Jiahui, Zhang Feng, Wu Qingping, Dai Jingsha, Li Yuanyu, Zhao Miao, Li Qi, Zhang Jumei, Wu Shi
Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, PR China.
Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Key Laboratory of Agricultural Microbiomics and Precision Application, Ministry of Agriculture and Rural Affairs, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, PR China.
Int J Food Microbiol. 2023 Dec 2;406:110348. doi: 10.1016/j.ijfoodmicro.2023.110348. Epub 2023 Aug 6.
Staphylococcus aureus and Staphylococcus argenteus have been implicated in food poisoning outbreaks, and have been found in various types of food products according to our previous study. Rice and flour products are popular and widely consumed around the world. However, limited data are available on the microbial safety of S. aureus in rice and flour products, and S. argenteus has never been reported. Thus, this study aimed to investigate the contamination of S. aureus and S. argenteus in 250 fresh rice and flour product samples from five cities in Guangdong, China. According to qualitative and quantitative analyses, 68 (27.2 %) and 11 (4.4 %) samples were positive for S. aureus and S. argenteus, including 9 samples that exceeded 100 MPN/g. For antibiotics susceptibility tests in 16 antibiotics, the S. aureus isolates exhibited higher rates of resistance and multidrug resistance than S. argenteus. The S. aureus and S. argenteus isolates were mainly resistant to penicillin (70.21 %; 79.17 %), tetracycline (20.21 %; 58.33 %) and azithromycin (19.68 %, 8.33 %). However, the other antibiotic resistance rates were <10 %. Furthermore, the genetic background of the isolates was analyzed by whole-genome sequencing (WGS). As a result, the S. aureus isolates were divided into 18 known sequence types (STs) and 4 novel STs (ST7675, ST7679, ST7680 and ST7682), which mainly belonged to ST188 (20.6 %) and ST6 (14.7 %). The S. argenteus isolates mainly belonged to ST2250 (90.9 %), with a novel type (ST7683). In total, 36 and 16 antibiotic resistance genes (ARGs) were found in S. aureus and S. argenteus isolates, respectively. In addition, 91 virulence genes (VFs) were detected in S. aureus isolates as well as 90 % of core VFs were similar to S. argenteus. More than 20 % of the S. aureus isolates carried the classic enterotoxin gene (sea-sec), but chp, cna and map were free in all S. argenteus isolates. Importantly, 33.8 % of S. aureus isolates belonged to the immune evasion cluster (IEC) type B, whereas most of S. argenteus isolates (90.9 %) belong to IEC type E. According to the phylogenetic analysis, the S. aureus and S. argenteus isolates in fresh rice and flour products may indicate loss or acquisition of ARGs and VFs to survive and adapt to the environment. Our study confirmed the presence of S. argenteus in rice and flour products at first and focused on the multi-dimensional systematic comparative analysis of S. aureus and S. argenteus to reveal their ubiquity and similarities or differences, and provide more accurate and effective basic information for follow-up monitoring and tracking.
金黄色葡萄球菌和银色葡萄球菌与食物中毒暴发有关，根据我们之前的研究，它们已在各类食品中被发现。大米和面粉制品广受欢迎且在全球被广泛食用。然而，关于大米和面粉制品中金黄色葡萄球菌微生物安全性的数据有限，且银色葡萄球菌从未被报道过。因此，本研究旨在调查来自中国广东省五个城市的250份新鲜大米和面粉制品样本中金黄色葡萄球菌和银色葡萄球菌的污染情况。根据定性和定量分析，68份（27.2%）和11份（4.4%）样本分别对金黄色葡萄球菌和银色葡萄球菌呈阳性，其中9份样本超过100 MPN/g。对于16种抗生素的药敏试验，金黄色葡萄球菌分离株比银色葡萄球菌分离株表现出更高的耐药率和多重耐药率。金黄色葡萄球菌和银色葡萄球菌分离株主要对青霉素耐药（70.21%；79.17%）、四环素耐药（20.21%；58.33%）和阿奇霉素耐药（19.68%，8.33%）。然而，其他抗生素耐药率均<10%。此外，通过全基因组测序（WGS）分析分离株的遗传背景。结果，金黄色葡萄球菌分离株被分为18种已知序列类型（STs）和4种新型STs（ST7675、ST7679、ST7680和ST7682），主要属于ST188（20.6%）和ST6（14.7%）。银色葡萄球菌分离株主要属于ST2250（90.9%）以及一种新型（ST7683）。在金黄色葡萄球菌和银色葡萄球菌分离株中分别总共发现了36个和16个抗生素耐药基因（ARGs）。此外，在金黄色葡萄球菌分离株中检测到91个毒力基因（VFs），并且90%的核心VFs与银色葡萄球菌相似。超过20%的金黄色葡萄球菌分离株携带经典肠毒素基因（sea-sec），但所有银色葡萄球菌分离株中均未检测到chp、cna和map。重要的是，33.8%的金黄色葡萄球菌分离株属于免疫逃避簇（IEC）B型，而大多数银色葡萄球菌分离株（90.9%）属于IEC E型。根据系统发育分析，新鲜大米和面粉制品中的金黄色葡萄球菌和银色葡萄球菌分离株可能表明ARGs和VFs的丢失或获得，以在环境中生存和适应。我们的研究首次证实了大米和面粉制品中存在银色葡萄球菌，并着重对金黄色葡萄球菌和银色葡萄球菌进行多维度系统比较分析，以揭示它们的普遍性以及异同点，为后续监测和追踪提供更准确有效的基础信息。
