Jiang Xiaobing, Yu Tao, Liang Yu, Ji Shengdong, Guo Xiaowei, Ma Jianmin, Zhou Lijun
College of Life Sciences, Henan Normal University, Xinxiang 453007, China.
College of Life Science and Technology, Xinxiang University, Xinxiang 453000, China.
Int J Food Microbiol. 2016 Jan 18;217:141-5. doi: 10.1016/j.ijfoodmicro.2015.10.022. Epub 2015 Oct 23.
In this study, efflux pump-mediated benzalkonium chloride (BC) resistance, including plasmid-encoded (Qac protein family and BcrABC) and chromosome-borne efflux pumps, was investigated in Listeria monocytogenes from retail food in China. Among the 59 L. monocytogenes strains, 13 (22.0%) strains were resistant to BC. The PCR results showed that bcrABC was harbored by 2 of 13 BC resistant strains. However, none of the qac genes were detected among the 59 strains. The bcrABC was absent in both of the plasmid cured strains, indicating that this BC resistance determinant was plasmid-encoded in the two bcrABC-positive strains. In the presence of reserpine, most of the bcrABC-negative strains had decreases in the MICs of BC, suggesting the existence of other efflux pumps and their role in BC resistance. After exposed to reserpine, the reduction in BC MICs was observed in the two cured strains, indicating that efflux pumps located on chromosome was also involved in BC resistance. Our findings suggest that food products may act as reservoirs for BC resistant isolates of L. monocytogenes and plasmid- and chromosome-encoded efflux pumps could mediate the BC resistance of L. monocytogenes, which is especially relevant to the adaption of this organism in food-related environments with frequent BC use.
在本研究中，对中国零售食品中分离的单核细胞增生李斯特菌中由外排泵介导的苯扎氯铵（BC）耐药性进行了研究，其中包括质粒编码的（Qac蛋白家族和BcrABC）以及染色体携带的外排泵。在59株单核细胞增生李斯特菌菌株中，有13株（22.0%）对BC耐药。PCR结果显示，13株BC耐药菌株中有2株携带bcrABC。然而，在这59株菌株中均未检测到qac基因。在两株质粒消除菌株中均未检测到bcrABC，这表明在两株bcrABC阳性菌株中，这种BC耐药决定簇是由质粒编码的。在利血平存在的情况下，大多数bcrABC阴性菌株的BC最低抑菌浓度（MIC）降低，这表明存在其他外排泵及其在BC耐药性中的作用。在暴露于利血平后，两株质粒消除菌株的BC MIC均降低，这表明位于染色体上的外排泵也参与了BC耐药性。我们的研究结果表明，食品可能是单核细胞增生李斯特菌BC耐药菌株的储存库，质粒和染色体编码的外排泵可介导单核细胞增生李斯特菌对BC的耐药性，这与该菌在频繁使用BC的食品相关环境中的适应性特别相关。
