现制饮品中金黄色葡萄球菌耐药及遗传特征研究

Study on antimicrobial resistance phenotype and genotype characterization of Staphylococcus aureus from freshly prepared beverages

中文关键词:  现制饮品  金黄色葡萄球菌  耐药性  全基因测序

英文关键词:freshly prepared beverage  Staphylococcus aureus  antimicrobial resistance  whole genome sequencing

中文摘要:

      目的 探究我国现制饮品中金黄色葡萄球菌抗生素耐药及遗传特征。方法 采用微量肉汤稀释法对金黄色葡萄球菌进行药敏测定, 同时提取菌株基因组DNA进行全基因组测序, 并使用生物信息学分析流程进行基因组特征数据挖掘。结果 现制饮品中43株金黄色葡萄球菌对10种抗生素的总体耐药率为88.4%, 分属9种耐药谱, 其中3株为耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus, MRSA)。多重耐药菌(multidrug resistant, MDR)占比16.3%, 主要分离自含乳现制饮品。耐受7类及以上抗生素金黄色葡萄球菌3株, 其中1株为MRSA。全基因测序进化分析表明菌株耐药表型与基因型具有良好的相关性, MRSA及多重耐药株出现明显聚集。43株菌属于16种多位点序列分型(multilocus sequence typing, MLST), 其中MRSA菌株包括1株ST45型和2株ST398型。多重耐药株ST型分别为ST5、7、15、59、121和398型。多重耐药MRSA株为ST398型。葡萄球菌肠毒素基因整体携带率为34.9%, 其中sea为主要基因型。MRSA菌株均不携带毒力基因, 多重耐药株肠毒素基因携带率为42.9%。3株主要来自含水果类现制饮品的ST1型菌株同时携带6种肠毒素基因, 但其仅对青霉素耐药或为敏感株。结论 我国现制饮品中金黄色葡萄球菌存在MRSA及多重耐药菌, 且该类菌株在遗传进化中聚类明显, 虽然MRSA菌株致病性相对较弱, 然而MDR菌株肠毒素基因的高携带率提示耐药金黄色葡萄球菌的潜在危害不容忽视。因此, 应加强现制饮品中金黄色葡萄球菌的耐药监测与防控。

英文摘要:

      Objective To explore the antimicrobial resistance phenotype and genotype characterization of Staphylococcus aureus (S. aureus) from freshly prepared beverages. Methods The antimicrobial susceptibility testing of S. aureus was carried out following broth microdilution method. Meanwhile, the genomic DNA of the isolates were extracted for whole genome sequencing, and then the bioinformatics analysis pipelines were implemented for genomic analysis. Results The overall resistance rate of the 43 S. aureus isolates from freshly prepared beverages against 10 categories of antibiotics was 88.4%. All isolates belonged to 9 kinds of antimicrobial resistance profiles, of which 3 isolates were methicillin-resistant S. aureus (MRSA). The overall multidrug resistant (MDR) rate was 16.3%, while MDR isolates were mainly originated from beverages made of milk and milk product. Three S. aureus isolates were resistant against 7 or more classes of antibiotics, one of which was MRSA. Whole genome sequencing and phylogenetic analysis showed that the antimicrobial resistance phenotypes and genotypes correlated well with each other. Moreover, the MRSA and MDR isolates showed obvious clustering in the phylogenetic tree. All of the 43 isolates belonged to 16 multilocus sequence types (MLST), from which MRSA isolates belonged to one ST45 and two ST398. The ST types of MDR isolates were ST5, 7, 15, 59, 121 and 398, respectively. The MDR-MRSA isolate was ST398. The 34.9% of all isolates harbored Staphylococcal enterotoxin genes, where sea was the main genotype. MRSA isolates did not harbor enterotoxin genes, while the harboring rate of enterotoxin genes of MDR isolates was 42.9%. All three ST1 isolates, which were mainly from freshly prepared beverages made of fruit, harbored 6 enterotoxin genes, however, they were only resistant to penicillin or being susceptible to all antibiotics tested. Conclusion MRSA and MDR S. aureus exist in freshly prepared beverages, and are closely correlated genetically. Although the pathogenicity of MRSA strains is relatively weak, high prevalence rate of enterotoxin genes in MDR isolates implicate that potent risk from resistant S. aureus should not be ignored. Therefore, the monitoring and prevention of antimicrobial resistant S. aureus in freshly prepared beverages should be strengthened in the future.