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

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 flaA 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 prfA or luxS 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 (flaA, luxS, prfA) of different serotype strains of L.monocytogenes, and serotype 1/2c strains were resistant to some antibiotics.