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目的了解从肉猪养殖和屠宰环境、猪胴体及猪回肠淋巴结和即食食品中分离的877株金黄色葡萄球菌中甲氧西林耐药基因(mecA)的分布,筛选出耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA),并对MRSA的耐药特征进行研究。方法经表型和耐热核酸酶基因(nuc基因)鉴定为金黄色葡萄球菌的877株菌,通过聚合酶链反应测定其mecA基因的携带情况,筛选出MRSA,并用微量肉汤稀释法对筛选出的MRSA进行耐药性分析。结果 877株实验菌株中有71株mecA基因阳性,为MRSA,检出率为8.1%;71株MRSA中有48株源自肉猪养殖和屠宰环境、猪胴体及猪回肠淋巴结,占该来源菌株的20.6%(48/233),为猪源性MRSA;23株分离自即食食品,占该来源菌株的3.6%(23/644),为食源性MRSA。猪源性MRSA检出率明显高于食源性MRSA(χ2=53.040,P<0.01)。71株MRSA对利奈唑胺、万古霉素、替加环素和呋喃妥因均敏感,对头孢西丁、苯唑西林和苄青霉素均耐药;对克林霉素、红霉素、四环素、环丙沙星、甲氧苄氨嘧啶/磺胺甲噁唑和庆大霉素的耐药率分别为98.6%(70株)、95.8%(68株)、88.7%(63株)、80.3%(57株)、80.3%(57株)和32.4%(23株);对左氧氟沙星、摩西罗星、利福平和奎奴普汀/达福普丁耐药者各1株;猪源性MRSA菌株对环丙沙星、四环素和甲氧苄氨嘧啶/磺胺甲噁唑的耐药率要明显高于食源性MRSA菌株(环丙沙星:χ2=29.110,P<0.01;四环素:χ2=18.816,P<0.01;甲氧苄氨嘧啶/磺胺甲噁唑:χ2=36.394,P<0.01)。耐3种以上抗生素的多重耐药MRSA菌株有70株(98.6%),耐药谱有8种。结论中国猪源性和食源性MRSA多重耐药现象严重。
Objective To investigate the distribution of methicillin-resistant gene (mecA) in 877 Staphylococcus aureus isolates from pig farms and slaughter environments, pig carcass and ileal lymph nodes and ready-to-eat foods, and to screen for methicillin-resistant golden yellow grape (Methicillin-resistant Staphylococcus aureus, MRSA), and MRSA resistance characteristics were studied. Methods 877 strains of Staphylococcus aureus were identified by the phenotype and heat-resistant nuclease gene (nuc gene). MRSA was screened by polymerase chain reaction (PCR) and MRSA was screened by micro-broth dilution MRSA out of resistance analysis. Results The positive rate of mecA gene in 71 strains of 877 isolates was MRSA with a detection rate of 8.1%. Forty-eight out of 71 strains of MRSA were derived from pig breeding and slaughter environment, pig carcass and ileal lymph nodes, Of MRSA were 20.6% (48/233) of swine origin and 23 were isolated from ready-to-eat foods, accounting for 3.6% (23/644) of MRSA. The detection rate of pig-derived MRSA was significantly higher than that of food-borne MRSA (χ2 = 53.040, P <0.01). 71 strains of MRSA were sensitive to linezolid, vancomycin, tigecycline and nitrofurantoin, cefoxitin, oxacillin and benzyl penicillin were resistant to clindamycin, erythromycin, tetracycline, cyclopropane The rates of resistance to triptolide, trimethoprim / sulfamethoxazole and gentamycin were 98.6% (70 strains), 95.8% (68 strains), 88.7% (63 strains) and 80.3% ), 80.3% (57 strains) and 32.4% (23 strains) respectively. One strain was resistant to levofloxacin, moxirole, rifampicin and quinovudine / dalfopristin The rates of resistance to tetracycline, trimethoprim and trimethoprim-sulfamethoxazole were significantly higher than those of foodborne MRSA strains (ciprofloxacin: χ2 = 29.110, P <0.01; tetracycline: χ2 = 18.816, P < 0.01; trimethoprim / sulfamethoxazole: χ2 = 36.394, P <0.01). There are 70 multi-resistant MRSA strains (98.6%) resistant to 3 or more antibiotics and 8 resistant spectrum. Conclusion The multi-drug resistance of swine and food-borne MRSA in China is serious.