Ledder R G, Gilbert P, Willis C, McBain A J
School of Pharmacy and Pharmaceutical Sciences, University of Manchester, Manchester, UK.
J Appl Microbiol. 2006 May;100(5):1132-40. doi: 10.1111/j.1365-2672.2006.02811.x.
Triclosan (TCS) exposure of Escherichia coli selects for tolerant clones, mutated in their enoyl-acyl carrier protein reductase (FabI). It has been inferred that this phenomenon is widespread amongst bacterial genera and might be associated with resistance to third party agents.
Ex-situ, low passage isolates of enteric, human axilla, human oral origin and bacteria isolated from a domestic drain, together with selected type cultures were exposed to escalating concentrations of TCS over 10 passages using a gradient plate technique. One fresh faecal isolate of E. coli was included as a positive control. TCS susceptibility was determined for all strains before and after exposure, whilst enteric isolates were additionally assessed for susceptibility towards chlorhexidine, tetracycline, chloramphenicol, nalidixic acid and ciprofloxacin, and the oral isolates towards chlorhexidine, tetracycline and metronidazole.
Triclosan exposure of E. coli markedly decreased TCS susceptibility. TCS susceptibility also decreased for Klebsiella oxytoca, Aranicola proteolyticus and Stenotrophomonas maltophilia. Susceptibility of the remaining 35 strains to TCS and the other test agents remained unchanged.
These data suggest that selection for high level resistance by TCS exposure is not widespread and appears to be confined to certain enteric bacteria, especially E. coli. Change in TCS susceptibility did not affect susceptibility towards chemically unrelated antimicrobials.
Acquired high-level TCS resistance is not a widespread phenomenon.
大肠杆菌暴露于三氯生（TCS）会筛选出在烯酰 - 酰基载体蛋白还原酶（FabI）中发生突变的耐受克隆。据推测，这种现象在细菌属中普遍存在，并且可能与对第三方药物的耐药性有关。
使用梯度平板技术，将来自肠道、人类腋窝、人类口腔以及从家庭排水管道分离出的低传代异地分离株，连同选定的模式培养物，在10代的过程中暴露于递增浓度的TCS。纳入一株新鲜的大肠杆菌粪便分离株作为阳性对照。在暴露前后测定所有菌株对TCS的敏感性，同时对肠道分离株额外评估对洗必泰、四环素、氯霉素、萘啶酸和环丙沙星的敏感性，对口腔分离株评估对洗必泰、四环素和甲硝唑的敏感性。
大肠杆菌暴露于三氯生显著降低了对TCS的敏感性。产酸克雷伯菌、解蛋白嗜盐碱杆菌和嗜麦芽窄食单胞菌对TCS的敏感性也有所降低。其余35株菌株对TCS和其他测试药物的敏感性保持不变。
这些数据表明，通过TCS暴露筛选出高水平耐药性的情况并不普遍，似乎仅限于某些肠道细菌，尤其是大肠杆菌。TCS敏感性的变化并未影响对化学性质不相关抗菌药物的敏感性。
获得性高水平TCS耐药性并非普遍现象。
