奶酪中抗生素抗性基因检测及奶酪分离乳酸菌耐药性分析

Detection of antibiotic resistance gene in cheese and analysis of resistance of lactobacillus isolated from cheese

抗生素抗性基因与细菌耐药性密切相关,其在食品中的存留状况越来越受到关注。奶酪是一种即食性发酵食品,在我国的消费量呈快速增长的趋势,本研究利用荧光定量PCR检测技术对国内外干酪和再制干酪样品中8大类抗生素抗性基因进行了检测,以期揭示其在奶酪制品中的存留和分布特点。结果显示:干酪和再制干酪这两类奶酪中存留了高丰度的抗性基因,除万古霉素类抗性基因外,其余7大类抗性基因在干酪和再制干酪样品中均检出,再制干酪中的各大类抗性基因检出率明显低于干酪样品,其中再制干酪中检出率较高的是氨基糖苷类、四环素类和大环内脂类-林可酰胺类-链阳性菌素B(MLSB)类抗性基因,干酪样品中检出率较高的是FCA(氟喹诺酮类、喹诺酮类、氟苯尼考、氯霉素和酰胺醇)类和氨基糖苷类抗性基因。分离自样品的18株乳酸菌药敏测试结果显示:耐药率较高的药物为磺胺恶唑(90.9%)和苯唑西林(86.36%);敏感率较高的是四环素(100%)和氨苄西林(100%)、氯霉素(81.8%);中介率最高的是环丙沙星(72.7%)和诺氟沙星(67.9%),上述研究结果表明市售奶酪中残留的抗生素抗性基因是一个不容忽视的问题。

Antibiotic resistance genes(ARGs)are closely related to antibiotic resistance in bacteria,and their existence in food has attracted more and more attention.Cheese is a kind of instant fermented food,and its consumptions grow rapidly in China.In this study,quantitative PCR was used to detect 8 kinds of antibiotic resistance genes in domestic and foreign cheese and processed cheese samples,and to characterize their existence and distribution in cheese.The results indicated that,there were abundant ARGs detected in the two types of cheese,except for vancomycin resistant genes.In processed cheese,the abundances of resistance genes were significantly lower than regular cheese samples.In addition,resistance genes of aminoglycoside and tetracycline class and the big ring lipid-forests amides-chain positive fungus element class B(MLSB)were detected at higher rates in processed cheese samples.In regular cheese,resistance genes against(fluoroquinolone,quinolone,florfenicol,chloramphenicol and amphenicol)and aminoglycoside were detected at higher rates.In our study,lactic acid bacteria were also isolated from the cheese with their antibiotic susceptibility tested.Within the 18 strains of lactic acid bacteria tested,it indicated that the resistant rate against sulfonoxazole were higher(90.9%),and that against benzoxicillin was 86.36%.In addition,within the strains of lactic acid bacteria tested,the susceptibilities against tetracycline as well as ampicillin were 100%,and chloramphenicol(81.8%).The highest intermediate rates were ciprofloxacin(72.7%)and against norfloxacin?was 67.9%.The results indicated that the existing antibiotic resistance genes in cheese might be a threat for the food safety and can not be ignored.