Abstract

Representative members of surface water microbiota were obtained from three unrelated municipal sites in Oklahoma by direct plating under selection by the hydrophobic biocide triclosan. Multiple methods were employed to determine if intrinsic triclosan resistance reflected resistance to hydrophobic molecules by virtue of outer membrane impermeability. While all but one organism isolated in the absence of triclosan were able to initiate growth on MacConkey agar, only one was able to initiate significant growth with triclosan present. In contrast, all bacteria selected with triclosan were identified as Pseudomonas spp. using 16S RNA gene sequencing and exhibited growth comparable to Pseudomonas aeruginosa controls in the presence of hydrophobic antibacterial agents to include triclosan. Two representative bacteria isolated in the absence of triclosan allowed for greater outer membrane association with the fluorescent hydrophobic probe 1-N-phenylnapthylamine than did two triclosan-resistant isolates. Compound 48/80 disruption of outer membrane impermeability properties for hydrophobic substances either partially or fully sensitized nine of twelve intrinsically resistant isolates to triclosan. These data suggest that outer membrane exclusion underlies intrinsic resistance to triclosan in some, but not all Pseudomonas spp. isolated by selection from municipal surface waters and implicates the involvement of concomitant triclosan resistance mechanisms.

抽象的

地表水微生物群的代表性成员是从俄克拉荷马州的三个不相关的市政场所通过疏水性杀菌剂三氯生的选择直接电镀获得的。由于外膜不渗透性，采用多种方法确定固有的三氯生抗性是否反映了对疏水性分子的抗性。虽然在不存在三氯生的情况下分离出的所有生物（除一种外）都可以在MacConkey琼脂上引发生长，但只有一种能够在存在三氯生的情况下引发明显的生长。相反，所有用三氯生选择的细菌均被鉴定为假单胞菌。使用16S RNA基因测序并显示出与铜绿假单胞菌相当的生长在疏水性抗菌剂存在下控制包括三氯生。在没有三氯生的情况下分离出的两个代表性细菌比两个对三氯生具有抗药性的分离物具有更大的与荧光疏水探针1- N-苯基萘胺的外膜缔合能力。化合物48/80破坏了疏水性物质的外膜不渗透性，使十二种固有抗性分离物中的九种对三氯生产生了部分或完全敏化。这些数据表明，在某些但不是全部假单胞菌属物种中，对三氯生的内在抗性是外膜排斥的基础。通过从市政地表水中选择而分离得到，并暗示了伴随的三氯生抗性机制的参与。