中国食源性和猪源性耐甲氧西林金黄色葡萄球菌遗传特性和耐药特征分析  

Genetic characterization and antimicrobial susceptibility analysis of methicillin-resistant Staphylococcus aureus isolated from ready-to-eat food and pig-related sources in China

作　　者：王伟 郭云昌[1] 裴晓燕[1] 胡豫杰[1] 白莉[1] 孙爱萍[1] 刘继开[1] 付萍[1] 李凤琴[1] 

机构地区：[1]国家食品安全风险评估中心卫生部食品安全风险评估重点实验室,北京100021

出　　处：《卫生研究》2013年第6期925-931,共7页Journal of Hygiene Research

摘　　要：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 study the mecA gene distribution in 877 strains of Staphylococcus aureus isolated from the environment of pig farm and slaughter house, pigcarcass and its iliac lymph nodes, and ready-to-eat foods in China as to screen the methicillin-resistant Staphylococcus aureus （MRSA）, and to evaluate the antimicrobial susceptibility of MRSA. Methods A total of 877 strains of S. aureus that had been pheno- typically identified by Gram staining, catalase test, ability to coagulate rabbit plasma, API STAPH as well as analysis of nuc gene, encoding for a S. aureus specific thermonu-clease were screened for MRSA by characterizing the mecA gene. The antimicrobial susceptibility of MRSA was tested in accordance with the broth microdilution method recommended by the Clinical and Laboratory Standards Institute. Results Of 877 S. aureus strains tested, 71 （8.1%, 71/887） were mecA positive and identified as MRSA, among which, 48 isolates were pig-associated and 23 isolates were ready-to-eat food-associated. The frequency of pig-associated MRSA was significantly higher than that of food-associated one （χ2 = 53.040, P〈 0.01 ）. All MRSA were susceptible to linezolid, vancomycin, tigecycline, and nitrofurantoin but resistant to cefoxitin, oxacillin and benzylpenicillin. Meanwhile, 98.6% （70 strains）, 95.8% （68 strains）, 88.7% （63 strains）, 80.3% （57 strains）, 80. 3% （57 strains） and 32. 4% （23 strains） MRSA exhibited the resistance to clindamycin, erythromycin, tetracycline, ciprofloxacin, trimethoprim/sulfamethoxazole, and gentamicin, respectively. Besides, one strain was resistant to each of antibiotics including levofloxacin, moxifloxacin, rifampicin, and quinupristin/dalfopristin. It was worth noting that the frequency of resistance to ciprofloxacin, tetracycline, and trimethoprim/sulfamethoxazole of pig-associated MRSA was significantly higher than that of food-associated MRSA （CIP：χ~2 =29. 110, P 〈0. 01, TET： χ2 = 18. 816, P 〈0. 01, TMP/ SMZ： χ2 =36. 394, P 〈0. 01

关 键 词：耐甲氧西林金黄色葡萄球菌 遗传特性 耐药 

分 类 号：R155.51[医药卫生—营养与食品卫生学] TS207.4[医药卫生—公共卫生与预防医学]