单增李斯特菌1/2c血清型菌株生物膜相关基因分析及耐药性研究

Biofilm related genes and the antibiotic resistance of Listeria monocytogenes 1 /2c serotypes strains

目的了解单增李斯特菌1/2c血清型菌株与其他血清型菌株的生物膜相关基因和抗生素耐药性是否有差异。方法采用聚合酶链反应技术对19个生物膜相关基因全长扩增测序分析,并与参考菌株EGD-e序列进行比对确定基因变异情况;根据K-B纸片法对选取的实验菌株进行药敏实验。结果氨基酸序列比对发现1/2c血清型菌株的fla A基因编码的氨基酸在141位点发生突变,其他血清型菌株则没有,1/2c血清型菌株在prf A基因编码的89氨基酸位点、lux S基因编码的112和140氨基酸位点都不发生突变,其他血清型菌株则发生突变。78.43%的1/2c血清型菌株对头孢西丁中度敏感,对氨苄西林、米诺环素、利福平和呋喃妥因有不同程度的耐药。结论不同血清型单增李斯特菌的fla A、lux S、prf A 3个基因编码的氨基酸在某些位点突变有一定的规律性;1/2c血清型单增李斯特菌对某些抗生素呈现不同程度的耐药。

Objective To understand the biofilm related gene diversity,and the differencesin antibiotic resistance among different serotypes strains of Listeria monocytogenes. Methods PCR methods was performed to amplify the 19 biofilm formation related genes based on full-length primers,and PCR products were compared with the sequence of reference strain EGD-e. Using the K-B method,which was recommended by Clinical and Laboratory Standards Institute to test the sensitivity of the experimental strains selected. Results By amino acid sequence alignment,the mutation of fla A at 141 loci were found in 1 /2c serotype strains,but not in other serotypes strains. No mutations occurred at some amino acid loci encoding by prf A or lux S of 1 /2c strains, but some mutations were found in other serotypes. According to drug susceptibility test, all L. monocytogenes isolates were sensitive to most antibiotic,and most 1 /2c strains（ 78. 43%） were intermediate to cefoxitin.1 /2c serotype strains had different resistantlevels to ampicillin,minocycline,rifampicin and nitrofurantion,but other serotypes were sensitive. Conclusion Mutation occurred regularly at some locus of the biofilm formation related genes（ fla A,lux S,prf A） of different serotype strains of L. monocytogenes,and serotype 1 /2c strains were resistant to some antibiotics.