猪肉中单核细胞增生李斯特菌的分离与耐药性研究

了解猪肉中单核细胞增生李斯特菌的污染情况、血清型和耐药性现状。按照国标GB 4789.30-2010程序分离猪肉中单核细胞增生李斯特菌；多重PCR确定血清型；纸片扩散法检测单核细胞增生李斯特菌对抗生素的敏感性。研究结果表明273份猪肉样本中有52（19.02%)个受单核细胞增生李斯特菌的污染，共检出78株该致病菌。33株（42.31%）、24株（30.71%）、16株（20.51%）、3株（3.85%）、2株（2.56%)分别被确定为血清型1/2a（或3a）、1/2b（或3b或7）、1/2c（或3c）、4a（或4c）和4b（或4d或4e）。所有菌株对氨苄西林、 氨苄西林/舒巴坦、亚胺培能、环丙沙星、左氧氟沙星、万古霉素都敏感，对四环素（20.51%）的耐药率最为严重。11.54%的菌株对临床治疗李斯特菌病的青霉素、庆大霉素、红霉素等抗生素出现耐药。tet(M)基因是单核细胞增生李斯特菌耐四环素的主要机制之一，接合型转座子Tn916与该菌四环素耐药散播有直接关系。

Isolation and Antimicrobial Susceptibilities of Listeria monocytogenes in Pork

To investigate the pork contamination by Listeria monocytogenes, its susceptibility to antimicrobial agents and serotypes, all strains were isolated by the GB 4789.30-2010 method; L. monocytogenes serotypes were identified by PCR; and antibiotic resistant profile of the isolates was examined using disc diffusion assay. A total of 273 pork samples were examined, out of which 52 samples (19.02%) were positive for L. monocytogenes and 78 strains were detected. And 33 (42.31%), 24 (30.71%), 16 (20.51%), 2 (2.56%), 3 (3.85%) of the isolates were identified as serotypes 1/2a (or 3a), 1/2b (or 3b or 7), 1/2c (or 3c), 4a (or4c)and 4b (or 4d or 4e), respectively. With disc diffusion assay, all strains were susceptible to the antibiotics, including ampicillin, ampicillin-sulbactam, imipenem, ciprofloxacin, levofloxacin, and vancomycin. However, the percentages of tetracycline resistances were higher. 11.54% isolates were resistant to penicillin, gentamicin, erythromycin. The conjugative transposon Tn916 is the important determinants of the resistance in spreading of the L. monocytogenes.