Genetic Characterization of Plasmid-Associated Benzalkonium Chloride Resistance Determinants in a Listeria monocytogenes Strain from the 1998-1999 Outbreak
Genetic Characterization of Plasmid-Associated Benzalkonium Chloride Resistance Determinants in a Listeria monocytogenes Strain from the 1998-1999 Outbreak
复制标题
DOI：
10.1128/aem.02056-10
复制
发表时间：
2010-12-01
影响因子：
4.4
通讯作者：
Kathariou, Sophia
中科院分区：
文献类型：
--
作者：
Elhanafi, Driss;Dutta, Vikrant;Kathariou, Sophia
季铵类化合物如苯扎氯铵（BC）在食品加工和医疗环境中广泛用作消毒剂。单核细胞增生李斯特菌bc耐药菌株与多州李斯特菌病暴发有关，并经常从食品加工厂分离出来。然而，单核增生乳杆菌对BC耐药的遗传基础仍然知之甚少。在这项研究中，我们在单核增生乳杆菌H7550中鉴定了一种质粒（pLM80）相关的BC耐药盒，该菌株与1998-1999年涉及受污染热狗的多州爆发有关。在质粒固化的H7550衍生株中，BC抗性盒（bcrABC）恢复了对BC （MIC, 40 μ g/ml）的抗性。卡带的所有三个基因都是赋予BC抗性所必需的。在亚致死（10 μ g/ml） BC暴露条件下，H7550 BC抗性基因的转录量增加，低温（4、8或25℃）下的转录量高于37℃，10 μ g/ml下的转录量高于20或40 μ g/ml。计算机分析表明，BC抗性盒是由一个IS1216复合转座子以及其他功能尚未确定的基因所包含。本研究的发现将进一步加深我们对这种生物对BC等消毒剂的适应性的理解，并可能有助于阐明BC耐药性在单核增生乳杆菌中传播的可能性。
Quaternary ammonium compounds such as benzalkonium chloride (BC) are widely used as disinfectants in both food processing and medical environments. BC-resistant strains of Listeria monocytogenes have been implicated in multistate outbreaks of listeriosis and have been frequently isolated from food processing plants. However, the genetic basis for BC resistance in L. monocytogenes remains poorly understood. In this study, we have characterized a plasmid (pLM80)-associated BC resistance cassette in L. monocytogenes H7550, a strain implicated in the 1998-1999 multistate outbreak involving contaminated hot dogs. The BC resistance cassette (bcrABC) restored resistance to BC (MIC, 40 mu g/ml) in a plasmid-cured derivative of H7550. All three genes of the cassette were essential for imparting BC resistance. The transcription of H7550 BC resistance genes was increased under sublethal (10 mu g/ml) BC exposure and was higher at reduced temperatures (4, 8, or 25 degrees C) than at 37 degrees C. The level of transcription was higher at 10 mu g/ml than at 20 or 40 mu g/ml. In silico analysis suggested that the BC resistance cassette was harbored by an IS1216 composite transposon along with other genes whose functions are yet to be determined. The findings from this study will further our understanding of the adaptations of this organism to disinfectants such as BC and may contribute to the elucidation of possible BC resistance dissemination in L. monocytogenes.