Loughlin M F, Jones M V, Lambert P A
Microbiology Research Group, School of Life and Health Sciences, Aston University, Birmingham B4 7ET, UK.
J Antimicrob Chemother. 2002 Apr;49(4):631-9. doi: 10.1093/jac/49.4.631.
Our objective was to determine whether strains of Pseudomonas aeruginosa can adapt to growth in increasing concentrations of the disinfectant benzalkonium chloride (BKC), and whether co-resistance to clinically relevant antimicrobial agents occurs. Attempts were made to determine what phenotypic alterations accompanied resistance and whether these explained the mechanism of resistance. Strains were serially passaged in increasing concentrations of BKC in static nutrient broth cultures. Serotyping and genotyping were used to determine purity of the cultures. Two strains were examined for cross-resistance to other disinfectants and antibiotics by broth dilution MIC determination. Alterations in outer membrane proteins and lipopolysaccharide (LPS) expressed were examined by SDS-PAGE. Cell surface hydrophobicity and charge, uptake of disinfectant and proportion of specific fatty acid content of outer and cytoplasmic membranes were determined. Two P. aeruginosa strains showed a stable increase in resistance to BKC. Co-resistance to other quaternary ammonium compounds was observed in both strains; chloramphenicol and polymyxin B resistance were observed in one and a reduction in resistance to tobramycin observed in the other. However, no increased resistance to other biocides (chlorhexidine, triclosan, thymol) or antibiotics (ceftazidime, imipenem, ciprofloxacin, tobramycin) was detected. Characteristics accompanying resistance included alterations in outer membrane proteins, uptake of BKC, cell surface charge and hydrophobicity, and fatty acid content of the cytoplasmic membrane, although no evidence was found for alterations in LPS. Each of the two strains had different alterations in phenotype, indicating that such adaptation is unique to each strain of P. aeruginosa and does not result from a single mechanism shared by the whole species.
我们的目标是确定铜绿假单胞菌菌株是否能够适应在浓度不断增加的消毒剂苯扎氯铵（BKC）中生长，以及是否会出现对临床相关抗菌药物的共同耐药性。我们试图确定耐药性伴随着哪些表型改变，以及这些改变是否能解释耐药机制。将菌株在静态营养肉汤培养物中于浓度不断增加的BKC中进行连续传代。通过血清分型和基因分型来确定培养物的纯度。通过肉汤稀释法测定最低抑菌浓度（MIC），检测两株菌株对其他消毒剂和抗生素的交叉耐药性。通过十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳（SDS - PAGE）检测外膜蛋白和表达的脂多糖（LPS）的变化。测定细胞表面疏水性和电荷、消毒剂的摄取以及外膜和细胞质膜中特定脂肪酸含量的比例。两株铜绿假单胞菌菌株对BKC的耐药性呈稳定增加。在两株菌株中均观察到对其他季铵化合物的共同耐药性；在一株中观察到对氯霉素和多粘菌素B的耐药性，在另一株中观察到对妥布霉素的耐药性降低。然而，未检测到对其他杀菌剂（洗必泰、三氯生、百里酚）或抗生素（头孢他啶、亚胺培南、环丙沙星、妥布霉素）的耐药性增加。伴随耐药性的特征包括外膜蛋白的改变、BKC的摄取、细胞表面电荷和疏水性以及细胞质膜的脂肪酸含量，尽管未发现LPS有改变。两株菌株中的每一株在表型上都有不同的改变，这表明这种适应性是铜绿假单胞菌的每个菌株所特有的，并非由整个物种共有的单一机制导致。
