大肠杆菌、金葡菌和铜绿假单胞菌对喹诺酮类药物的耐药性研究

目的 研究大肠埃希氏杆菌（大肠杆菌）、金黄色葡萄球菌（金葡菌）和铜绿假单胞菌分别暴露于喹诺酮类药物、染料、紫外线后耐药性产生情况及不同浓度喹诺酮类药物作用于这三种细菌后其生长和形态特征的改变。方法 采用琼脂平板表面涂菌和试验双倍稀释法。结果 引起细菌耐喹诺酮类药物的主要原因是低浓度喹诺酮类产生耐药性。细菌经不同浓度环丙沙星作用后，产生不同程度的数量减少和形态改变。结论 大肠杆菌最容易产生喹诺酮耐药性，在环丙沙星作用后量易发生形态和耐药性改变，而不易被喹诺酮类药物杀灭。

Study of quinolones resistance in Escherichia coli, Staphylococcus aureus and Pseudomonas areuginosa]

OBJECTIVE: To investigate the factors of quinolone-resistance mediating in Escherichia coli(E. coli), Staphylococcus aureus (S. aureus) and Pseudomonas areuginosa(P. areuginosa) and examine the characteristic changes and quinolones resistance of these bacteria after exposing them to quinolones, dye-materials, and ultraviolet respectively. METHODS: The agar plate inoculating on surface and tube broth two-fold dilution methods were adopted. RESULTS: Quinolone-resistance was mainly mediated by repeated exposure of the bacteria to low level concentration of quinolone. No quinolone-resistance was found after exposure of the bacteria to ultra-violet and dye materials such as Ethidium bromide and Acry-orange. Among the three kinds of bacteria, E. coli tended to have stable high level of quinolone- resistance(MICs > or = 256 mg/L). S. aureus acquired mediate level of quinolone-resistance(MICs < or = 32 mg/L). P. aeruginosa acquired a high but not stable level(MICs > or = 256 mg/L) of resistance. These bacteria were cultured in the concentration of 1/2 x MIC, 1 x MIC, 2 x MIC, 4 x MIC, 5 x MIC ciprofloxacin, and were compared with those cultured in the same concentration of sparfloxacin and cefotaxime. After being affected by ciprofloxacin, the E. coli underwent apparent morphologic changes, such as becoming wider(2-3 times), longer(10-30 times), thread-like, and fewer in number. These changes were consistent with the increase of quinolone concentrations. The morphologic changes in P. aeruginosa and S. aureus were not so obvious as those in E. coli. Sparfloxacin and cefotaxime mainly led to the decrease in the numbers of bacteria. When the concentration of Sparfloxacin and cefotaxime were 4 x MICs, the changes of P. aeruginosa and S. aureus were less obvious. CONCLUSION: The bacteria's quinolone-resistance is mainly induced by the quinolone itself. The quinolone-resistance is more likely occur in E. coli than in P. aeruginosa and S. aureus. After exposure of the bacteria to ciprofloxacin, E. coli might have most apparent morphologic changes and occurrence resistance.