人们都知道，消毒剂使用时间长了，细菌就会产生一定抵抗力，必须用更高浓度的消毒剂才能达到抑菌或杀菌目的。而爱尔兰研究人员最新研究发现，消毒剂还会“训练”细菌，使其对抗生素药物也产生耐药性，从而形成“超级病菌”。
国立爱尔兰大学研究人员在新一期英国《微生物学》杂志上报告说，他们在实验过程中向绿脓杆菌的培养液中添加消毒剂，并且不断增加消毒剂的用量。结果发现，这种细菌会努力适应消毒剂并在这种“敌我斗争”中存活下去。
让研究人员意想不到的是，当他们把对消毒剂产生抵抗力的绿脓杆菌置于临床常用抗生素“环丙沙星”环境中时，绿脓杆菌竟然有了耐药性。也就是说，在之前未接触过抗生素的情况下，绿脓杆菌在消毒剂的“训练”下就可以产生耐药性。
研究人员介绍说，细菌本身可以不断适应有消毒剂的环境，变得能更有效地把细菌细胞内的抗菌物质排出。这时细菌的遗传物质DNA（脱氧核糖核酸）已经发生了一定改变，使其对某种抗生素产生特定耐药性。
绿脓杆菌是常见的一种致病菌，那些自身免疫系统弱或患有免疫系统疾病的人容易感染这一细菌，它也是医院内重要的细菌感染类型之一。因此，医院常使用消毒剂擦拭室内以及医疗器械等各处的表面，以防绿脓杆菌感染。
研究人员说，他们的研究结果对于研究如何更加有效地控制医院内细菌感染非常重要，而且也有助于进一步理解细菌产生耐药性的环境影响因素。（生物谷Bioon.com）
生物谷推荐原始出处：
Microbiology 156 (2010), 30-38; DOI 10.1099/mic.0.029751-0
Effect of subinhibitory concentrations of benzalkonium chloride on the competitiveness of Pseudomonas aeruginosa grown in continuous culture
Paul H. Mc Cay, Alain A. Ocampo-Sosa and Gerard T. A. Fleming
Department of Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland
This study investigates the link between adaptation to biocides and antibiotics in Pseudomonas aeruginosa. An enrichment continuous culture of P. aeruginosa NCIMB 10421 (MIC 25 mg BKC l–1) was operated (D=0.04 h–1, 792 h) with added benzalkonium chloride (BKC). A derivative, PA-29 (696 h), demonstrated a >12-fold decrease in sensitivity to the biocide (MIC >350 mg BKC l–1). The variant demonstrated a 256-fold increase in resistance to ciprofloxacin, with a mutation in the gyrA gene (Thr-83Ile). Similarly, culturing of the original strain in a continuous-culture system with ciprofloxacin selection pressure led to the evolution of BKC-adapted populations (MIC 100 mg BKC l–1). Efflux pump activity predominantly contributed to the developed phenotype of PA-29. An amino acid substitution (Val-51Ala) in nfxB, the Mex efflux system regulator gene, was observed for PA-29. Overexpression of both MexAB-OprM and MexCD-OprJ was recorded for PA-29. Similarly, mexR, a repressor of the Mex system, was downregulated. Competition studies were carried out in continuous culture between PA-29 and the original strain (in the presence of subinhibitory concentrations of BKC). The outcome of competition was influenced by the concentration of biocide used and the nature of limiting nutrient. The inclusion of 1 mg BKC l–1 in the medium feed was sufficient to select (S=0.011) for the BKC-adapted strain in magnesium-limited culture. Conversely, the presence of 10 mg BKC l–1 in the medium supply was insufficient to select for the same organism (S=–0.017) in the glucose-limited culture. These results indicate the importance of environmental conditions on selection and maintenance of biocide adaptation.
