猪肉中单核细胞增生李斯特菌的分离与耐药性研究

Isolation and Antimicrobial Susceptibilities of Listeria monocytogenes in Pork

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。

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.