Falsafi T, Ehsani A, Niknam V
Department of Biology, Azzahra University, Tehran, Iran.
Indian J Med Microbiol. 2009 Oct-Dec;27(4):335-40. doi: 10.4103/0255-0857.55452.
In gram-negative bacteria, active efflux pumps that excrete drugs can confer resistance to antibiotics however, in Helicobacter pylori this role is not well established. The purpose of this study is to evaluate the role of active efflux in resistance of H. pylori isolates to antibiotics.
Twelve multiple antibiotic resistant (MAR) isolates resistant to at least four antibiotics, including beta-lactams, metronidazole, tetracycline, erythromycin, and ciprofloxacin; three resistant to only beta-lactams, and two hyper-susceptible isolates, were obtained from screening of 96 clinical isolates of H. pylori . Their minimal inhibitory concentrations (MICs) for antibiotics and ethidium-bromide (EtBr) were compared in the presence- and absence of a proton-conductor, carbonyl cyanide-m chlorophenyl-hydrazone (CCCP) using agar-dilution and disc diffusion. Drug accumulation studies for EtBr and antibiotics were assessed in the presence and absence of CCCP using spectrofluorometry.
MIC of EtBr for eight MAR-isolates was decreased two- to four-folds in the presence of CCCP, of which five showed reduced MICs for beta-lactam, metronidazole, tetracycline, and ciprofloxacin with CCCP. Accumulation of EtBr by the MAR-isolates was rapid and not dependant on the pattern of multiple resistance. Antibiotic accumulation assay confirmed the presence of energy-dependant efflux of beta-lactam, metronidazole, tetracycline, and ciprofloxacin, but no erythromycin in five MAR isolates. Energy-dependant efflux of EtBr or antibiotics was not observed for four MAR-isolates, and three isolates were resistant only to beta-lactams.
Energy-dependant efflux plays a role in the resistance of H. pylori clinical isolates to structurally unrelated antibiotics in a broadly specific multidrug efflux manner. Difference in the efflux potential of MAR isolates may be related to the presence or absence of functional efflux-pumps in diverse H. pylori isolates.
在革兰氏阴性菌中，能够排出药物的活性外排泵可使细菌产生抗生素耐药性，然而在幽门螺杆菌中，这一作用尚未明确。本研究旨在评估活性外排在幽门螺杆菌分离株对抗生素耐药性中的作用。
从96株幽门螺杆菌临床分离株中筛选出12株对至少四种抗生素耐药的多重抗生素耐药（MAR）分离株，这些抗生素包括β-内酰胺类、甲硝唑、四环素、红霉素和环丙沙星；3株仅对β-内酰胺类耐药，以及2株超敏感分离株。使用琼脂稀释法和纸片扩散法，在存在和不存在质子导体羰基氰化物间氯苯腙（CCCP）的情况下，比较它们对抗生素和溴化乙锭（EtBr）的最低抑菌浓度（MIC）。使用荧光分光光度法，在存在和不存在CCCP的情况下，评估EtBr和抗生素的药物积累研究。
在存在CCCP的情况下，8株MAR分离株对EtBr的MIC降低了2至4倍，其中5株在使用CCCP时对β-内酰胺类、甲硝唑、四环素和环丙沙星的MIC降低。MAR分离株对EtBr的积累迅速，且不依赖于多重耐药模式。抗生素积累试验证实，5株MAR分离株中存在β-内酰胺类、甲硝唑、四环素和环丙沙星的能量依赖性外排，但不存在红霉素的能量依赖性外排。4株MAR分离株未观察到EtBr或抗生素的能量依赖性外排，3株分离株仅对β-内酰胺类耐药。
能量依赖性外排在幽门螺杆菌临床分离株对结构不相关抗生素的耐药性中以广泛特异性的多药外排方式发挥作用。MAR分离株外排潜力的差异可能与不同幽门螺杆菌分离株中功能性外排泵的存在与否有关。
