2009—2018年广州市即食食品中金黄色葡萄球菌污染情况和菌型特征

目的 分析2009—2018年广州市零售即食食品中金黄色葡萄球菌污染情况,以及菌株肠毒素基因、耐药表型特征。方法 从广州市辖11个区的农贸市场、超市随机购买零售即食食品,增菌后分离金黄色葡萄球菌。对所有菌株进行多位点序列分型(MLST)、抗生素敏感性试验,并检测24种肠毒素基因。对耐甲氧西林金黄色葡萄球菌(MRSA)进行葡萄球菌染色体盒(staphylococcal cassette chromosome mec,SCCmec)分型。结果 2009—2018年广州市采集的1 399份即食食品中共分离出157株金黄色葡萄球菌(简称金葡菌)(检出率为11.22%),其中熟猪肉中金葡菌检出率(17.95%)相比非熟肉食品中金葡菌检出率(9.43%)差异有统计学意义(P<0.001)；抗生素敏感性检测结果显示7株金葡菌为MRSA,检出率为0.5%；157株金葡菌对青霉素的耐药率高达83.43%,其次是四环素(55.41%)、红霉素(41.40%)、氯霉素(29.30%)、克林霉素(21.02%)、复方新诺明(20.40%)及庆大霉素(14.01%)；对环丙沙星、苯唑西林及头孢西丁的耐药率均≤10.0%,对万古霉素、达托霉素、利奈唑胺均敏感。即食食品中优势克隆复合体(CC)为CC59(25.48%),其次为CC6(17.83%)、CC398(10.83%)。菌株特征分析结果发现对3种或3种以上抗菌药耐药的菌株占比,CC59和CC398大于CC6(P<0.001),而所有CC6菌株都携带seg, sei, sem, sen, seo及seu,远高于CC59(P<0.001)。结论 广州市即食食品中的优势菌群是CC59、 CC6和CC398,这3种优势克隆群在国内临床患者和食物中毒分离株中也很常见,需要公共卫生部门引起重视,加强对市售即食食品中金葡菌的监测。

Contamination status and characteristics of Staphylococcus aureus in ready-to-eat foods in Guangzhou from 2009 to 2018

Objective To investigate the prevalence, antimicrobial susceptibility, and enterotoxin gene of Staphylococcus aureus (S. aureus) isolates in ready-to-eat (RTE) foods in Guangzhou from 2008 to 2019. To investigate the prevalence, antimicrobial susceptibility, and enterotoxin gene of Staphylococcus aureus (S. aureus) isolates in ready-to-eat (RTE) foods in Guangzhou during 2008-2019.Methods RTE food samples were randomly collected from retail outlets and supermarkets in 11 districts of Guangzhou and the isolation and identification of S. aureus were performed. All isolated S. aureus were tested for antimicrobial susceptibility, enterotoxin genes and multilocus sequence typing (MLST). Methicillin resistant S. aureus (MRSA) isolates were further characterized by staphylococcal cassette chromosome mec (SCCmec) typing. RTE food samples were randomly collected from retail outlets and supermarkets in 11 districts of Guangzhou and the isolation and identification of S. aureus were performed from these samples. All isolated S. aureus were tested for antimicrobial susceptibility, enterotoxin genes, and multilocus sequence typing (MLST); methicillin resistant S. aureus (MRSA) isolates were further characterized by staphylococcal cassette chromosome mec (SCCmec) typing.Results A total of 157 S.aureus isolates(11.22%) were detected from 1 399 RTE food samples in Guangzhou from 2009 to 2018. The prevalence of S. aureus in cooked pork samples was significantly higher than those in non-meat samples (17.95% vs 9.43%, P<0.001). Of the 157 S. aureus isolates , seven were confirmed as MRSA by cefoxitin disc diffusion test. Among the 157 isolates, the highest resistance was to penicillin G (83.43%), followed by tetracycline (55.41%), erythromycin (41.40%), chloramphenicol (29.30%), clindamycin (21.02%), trimethoprim/sulphamethoxazole (20.40%) and gentamicin (14.01%), and 4.46%-10.83% isolates were resistant to cefoxitin, oxacillin and ciprofloxacin. All the isolates were sensitive to vancomycin, daptomycin and linezolid. Notably, 82.5% and 100% isolates were resistant to at least three antimicrobials in CC59 and CC398, respectively, and the resistance levels were significantly higher than that of CC6 isolates (14.81%) (P<0.001). The positive rates of seg, sei, sem, sen, seo and seu in CC6 and CC59 isolates were 100% and 42% , respectively (P<0.001). A total of 157 S.aureus isolates(11.22%) were detected from 1399 RTE food samples in Guangzhou from 2009 to 2018. The prevalence of S. aureus in cooked pork samples was significantly higher than those in non-meat samples (17.95% vs 9.83%, P<0.001). Of the 157 S. aureus isolates, seven were confirmed as MRSA by cefoxitin disc diffusion test. Among the 157 isolates, the highest resistance was to penicillin G (83.43%), followed by tetracycline (55.41%), erythromycin (41.40%), chloramphenicol (29.30%), clindamycin (21.02%), trimethoprim/sulphamethoxazole (20.40%) and gentamicin (14.01%), and 4.46%-10.83% isolates were resistant to cefoxitin, oxacillin, and ciprofloxacin. All the isolates were sensitive to vancomycin, daptomycin, and linezolid. Notably, 82.5% and 100%, isolates were resistant to at least three antimicrobials in CC59 and CC398, respectively, and the resistance levels were significantly higher than that of CC6 isolates (14.81%) (P<0.001). The positive rates of seg, sei, sem, sen, seo, and seu in CC6 and CC59 isolates were 100% and 42%, respectively (P <0.001). Conclusion CC59, CC6 and CC398 were the predominant S.aureus isolates in RTE food samples in Guangzhou, and these isolates had been linked to human infections and Staphylococcal food poisoning outbreaks in China. It was a serious public health risk and highlights the need to implement good hygiene practices. CC59, CC6, and CC398 are the prodominant S.aureus isolates in RTE food samples in Guangzhou, and these isolates have been linked to human infections and Staphylococcal food poisoning outbreaks in China. This is a serious public health risk and highlights the need to implement good hygiene practices.