云南省牛乳中单核细胞增生李斯特氏菌的分布特征、耐药性及毒力研究

目的 分析云南省牛乳中单核细胞增生李斯特氏菌(Listeria monocytogenes)的分布特征、耐药性及毒力现状.方法 采集云南省主要奶产区牛乳样本,按照GB 4789.30—2016方法分离单核细胞增生李斯特氏菌疑似菌株,采用飞行时间质谱技术结合16S rDNA测序对疑似菌株进行鉴定;采用微量肉汤稀释法对分离...

Distribution characteristics, drug resistance and virulence of Listeria monocytogenes in milk in Yunnan province

Objective To understand and analyze the distribution characteristics, drug resistance and virulence of Listeria monocytogenes in the milk of Yunnan Province. Methods Collect milk samples from major milk producing areas in Yunnan Province, and isolate suspected Listeria monocytogenes strains according to GB4789.30-2016 method, and use time-of-flight mass spectrometry technology combined with 16S rDNA sequencing to identify the suspected strains; use micro broth dilution method Antibiotic susceptibility test was performed on the isolated strains; polymerase chain reaction (PCR) technology was used to detect the existence of 7 virulence genes in Listeria monocytogenes. Results A total of 158 samples were found in 4 of Listeria monocytogenes. The detection rate was 2.53%; 8 strains were isolated. Among them, the detection rate in raw milk was 3.36%, and it was not detected in pasteurized milk. In raw milk, the detection rates of Holstein milk, buffalo milk, and yak milk were 2.13%, 0%, and 20.00%, respectively; the detection rates of standardized cattle farms, dairy cooperatives, and self-employed were 2.50%, 1.51%, and 15.38%, the detection rates of manual milking and mechanical milking were 11.76% and 1.96%. .The drug sensitivity results showed that 8 strains were resistant to penicillin. Their resistance rates to tetracycline, compound trimethoprim, and erythromycin were 87.50%, 75.00%, and 50.00%, respectively, and their multi-drug resistance rate was 75.00%; But all strains were sensitive to ampicillin. The 7 virulence genes were distributed in different degrees in 8 strains, ranging from 12.50% to 75.00%. Conclusion There is a certain degree of L. monocytogenes contamination in milk in Yunnan Province, especially raw milk. Moreover, these L. monocytogenes strains from milk have universal drug resistance and carry a certain degree of virulence genes, which have potential risks to the safety of consumers. Therefore, the health supervision and management of mil should be strengthened.