56株食源性单增李斯特菌耐药性测定及耐药基因的检测

Antibacterial drugs resistance and related genes detection of 56 food-borne Listeria monocytogenes

为调查新疆部分食源性单增李斯特菌的药物敏感性和相关耐药基因的携带现况,采用微量肉汤稀释法(MIC)和K-B琼脂扩散法对56株单增李斯特菌进行18种抗菌药物敏感性试验。通过PCR方法进行12种相关耐药基因检测,并对耐药基因进行测序分析。结果表明,28.6%(16/56)的菌株微量肉汤稀释法检测耐药,而K-B琼脂扩散法检测19.6%(11/56)菌株耐药。56株单增李斯特菌均对青霉素、氨苄西林、亚胺培能、庆大霉素、万古霉素、左氧氟沙星、利福平敏感,对四环素、复方新诺明、链霉素、强力霉素、卡那霉素耐药。微量肉汤稀释法检测发现,菌株对四环素、复方新诺明、链霉素耐药率较高,分别为12.5%(7/56)、10.7%(6/56)、10.7%(6/56),多重耐药菌株占7.1%(4/56)。在18株表型耐药菌株中,61.1%(11/18)的菌株携带相应的耐药基因,四环素类耐药基因以tetM为主,红霉素耐药基因为ermB,氯霉素素耐药基因为cat。而在38株非耐药表型菌株中,氨基糖苷类耐药基因aac(6’)-Ib-cr和红霉素耐药基因ermB的检出率分别高达57.9%和39.5%。扩增片段核苷酸序列与参考序列同源性为95%~100%。新疆食源性单增李斯特菌出现耐药,且耐药表型与耐药基因不完全符合,应引起关注。

The aim of the study was to understand the status of antibacterial drugs resistance and related resistance genes in food-borne Listeria monocytogenes in Xinjiang.Broth microdilution method and K-B agar diffusion method were used to determine 18 antibacterial drugs sensitivity against 56 Listeria monocytogenes.The distribution of 12 related resistance genes were detected by PCR.The resistance genes were sequenced and analyzed.In result,28.6%(16/56) resistant strains were detected by the broth microdilution method,and 19.6%(11/56) resistant strains were detected by the K-B agar diffusion method.56 strains were sensitive to penicillin,ampicillin,imipenem,gentamicin,vancomycin,levofloxacin and rifampin and resistant to tetracycline,trimethoprim-sufamethoxazole,streptomycin,doxycycline and kanamycin.By the broth microdilution method,the resistance rates to tetracycline,trimethoprim-sufamethoxazole,and streptomycin were 12.5%(7/56),10.7%(6/56),10.7%(6/56),respectively.The multi-drug resistance strains were 7.1%(4/56).Among the 18 resistant phenotype strains,61.1%(11/18) of the strains carried correspond resistance genes.The tetracycline resistance gene was mainly tet M,erythromycin resistance gene was erm B,and chloramphenicol resistance gene was cat.Among the 38 non-resistant phenotype strains,the detection rates of aminoglycoside resistance gene aac(6’)-Ib-cr and erythromycin resistance gene erm B were as high as 57.9% and39.5%,respectively.The nucleotide sequence of the resistance genes had 95%-100% homology with the reference sequence.In conclusion,antibacterial drugs resistance of food-borne Listeria monocytogenes in Xinjiang and inconsistent between resistant phenotype and resistant genes should be concerned.