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目的研究2012年中国23个省市自治区10类食品中分离的635株单核细胞增生李斯特菌的耐药特征及多位点序列分型(multilocus sequence typing,MLST)测定。方法采用CLSI推荐的微量肉汤稀释法,选择氨苄西林、复方新诺明、四环素、庆大霉素、红霉素、环丙沙星、氯霉素和万古霉素8种抗生素,对耐药株进行MLST分型。结果 635株单增李斯特菌检测出66株耐药菌,平均耐药率为10.39%。耐四环素菌株最多为49株,其次为耐环丙沙星20株、红霉素10株、氯霉素7株、复方新诺明3株、氨苄青霉素1株、庆大霉素1株、万古霉素1株。耐受2种抗生素有8株,耐受3种及以上抗生素有7株。77株菌耐药性介于中介度,其中75株菌对环丙沙星耐药性介于中介度。耐药株MLST分型表明,ST155、ST9、ST705和ST87为我国单增李斯特菌耐药株常见型别。四环素和四环素-红霉素-氯霉素耐药谱在MLST聚类分析中有集中趋势,耐药菌株主要来源于熟肉制品和中式凉拌荤菜。结论我国目前食品来源的单增李斯特菌耐药率普遍较低,但与往年相比呈现逐渐增加的趋势。耐药株的主要MLST型别分布与相关耐药谱在聚类分析中相互关联。
Objective To investigate the drug resistance and multilocus sequence typing (MLST) of 635 Listeria monocytogenes isolated from 10 kinds of food in 23 provinces in China in 2012. Methods Eight kinds of antibiotics such as ampicillin, cotrimoxazole, tetracycline, gentamicin, erythromycin, ciprofloxacin, chloramphenicol and vancomycin were selected by CLSI recommended microdilution method. Strains were MLST typed. Results Sixty-six strains of Listeria monocytogenes were detected, with an average resistance rate of 10.39%. Tetracycline resistant strains were up to 49, followed by 20 ciprofloxacin resistant, 10 erythromycin, 7 chloramphenicol, 3 cotrimoxazole, 1 ampicillin, 1 gentamicin, eternal A strain of 8 strains of 2 kinds of antibiotics, 7 strains of 3 kinds and above of antibiotics. The resistance of 77 strains was intermediate, of which 75 were intermediate to ciprofloxacin. The resistant strains MLST typing showed that ST155, ST9, ST705 and ST87 were common types of Listeria monocytogenes in China. Tetracycline and tetracycline-erythromycin-chloramphenicol resistance spectrum in the MLST clustering analysis has a tendency to focus, resistant strains mainly come from cooked meat products and Chinese cold meat dishes. Conclusion At present, the drug-resistant Listeria monocytogenes in our country is generally low, but it shows an increasing trend compared with previous years. The major MLST phenotypes of drug-resistant strains were correlated with the related resistance spectrum in cluster analysis.