Wang Wei, Guo Yunchang, Pei Xiaoyan, Hu Yujie, Bai Li, Sun Aiping, Liu Jikai, Fu Ping, Li Fengqin
Key Lab of Food Safety Risk Assessment, Ministry of Health, China National Centre for Food Safety Risk Assessment, Beijing 100021, China.
Wei Sheng Yan Jiu. 2013 Nov;42(6):925-31.
To study the mecA gene distribution in 877 strains of Staphylococcus aureus isolated from the environment of pig farm and slaughter house, pig carcass 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.
A total of 877 strains of S. aureus that had been phenotypically 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.
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 (chi2 = 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: chi2 = 29.110, P < 0.01, TET: chi2 = 18.816, P < 0.01, TMP/ SMZ: chi2 = 36.394, P < 0.01). It should be pointed out that 70 (98.6%) strains of MRSA were multi-drug resistant and eight spectrums of antimicrobial susceptibility were observed.
The multi-drug resistant MRSA isolated from pig- and food-associated matrixin China is very serious.
研究从中国猪场和屠宰场环境、猪胴体及其髂淋巴结以及即食食品中分离出的877株金黄色葡萄球菌中mecA基因的分布情况，以筛选耐甲氧西林金黄色葡萄球菌（MRSA），并评估MRSA的抗菌药敏性。
通过革兰氏染色、过氧化氢酶试验、凝固兔血浆能力、API STAPH以及对编码金黄色葡萄球菌特异性热核酸酶的nuc基因进行分析，对877株经表型鉴定的金黄色葡萄球菌进行mecA基因特征分析，筛选MRSA。按照临床和实验室标准协会推荐的肉汤微量稀释法检测MRSA的抗菌药敏性。
在检测的877株金黄色葡萄球菌中，71株（8.1%，71/887）mecA基因阳性，被鉴定为MRSA，其中48株分离自与猪相关的样本，23株分离自与即食食品相关的样本。与猪相关的MRSA的检出率显著高于与食品相关的MRSA（χ² = 53.040，P < 0.01）。所有MRSA对利奈唑胺、万古霉素、替加环素和呋喃妥因敏感，但对头孢西丁、苯唑西林和苄青霉素耐药。同时，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）的MRSA分别对克林霉素、红霉素、四环素、环丙沙星、甲氧苄啶/磺胺甲恶唑和庆大霉素耐药。此外，有1株对左氧氟沙星、莫西沙星、利福平以及奎奴普丁/达福普汀中的每种抗生素均耐药。值得注意的是，与猪相关的MRSA对环丙沙星、四环素和甲氧苄啶/磺胺甲恶唑的耐药率显著高于与食品相关的MRSA（环丙沙星：χ² = 29.110，P < 0.01；四环素：χ² = 18.816，P < 0.01；甲氧苄啶/磺胺甲恶唑：χ² = 36.394，P < 0.01）。应当指出的是，70株（98.6%）MRSA为多重耐药菌，观察到8种抗菌药敏谱。
在中国，从与猪和食品相关的基质中分离出的多重耐药MRSA情况非常严重。
