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目的比较幽门螺杆菌(Hp)对甲硝唑(MTZ)、克拉霉素(CLA)、阿莫西林(AMX)体外获得耐药性的难易程度,初步探索 Hp 耐药的发生规律,指导临床合理用药。方法所有 Hp 均为来源于2004年12月至2005年7月于浙江大学附属儿童医院进行胃镜检查患儿的临床分离株。采用Etest 法测定最低抑菌浓度(MIC 值),筛选出对3种抗生素均敏感的菌株,并进行浓度递增法体外诱导。琼脂稀释法测定各菌株诱导前后的 MIC 值,以比较 Hp 对3种抗生素诱导的难易程度。结果共筛选出7株对3种抗生素均敏感的 Hp,经过6～17代体外诱导,所有7株均获得 MTZ 耐药,3株获得 CLA 耐药,未获得 AMX 耐药。Hp 对3种抗生素的可诱导倍数不同,MTZ 多数(6/7)达32倍以上,CLA 为1～256倍,AMX 为2～16倍。诱导后菌株经不含抗生素的培养基传代3次,对 MTZ 与 CLA的 MIC 值较传代前变化差异无统计学意义(P>0.05),而对 AMX 的 MIC 值较传代前降低(P<0.05)。结论儿童感染的 Hp 经体外诱导很容易获得 MTZ 耐药,可以获得 CLA 耐药,但很难获得AMX 耐药;体内外实验的一致性提示 Hp 对抗生素耐药主要为获得性耐药;体外诱导耐药发生的难易程度有助于预测实际耐药率的变迁,为根除治疗中选择抗生素提供依据。
Objective To compare the ease of drug resistance of Helicobacter pylori (Hp) against metronidazole (MTZ), clarithromycin (CLA) and amoxicillin (AMX) in vitro and to explore the pathogenesis of Hp resistance and guide clinical Rational use of medicine. Methods All Hp were clinical isolates from children undergoing gastroscopy at Children’s Hospital of Zhejiang University from December 2004 to July 2005. The minimum inhibitory concentration (MIC) was determined by Etest. Strains sensitive to three kinds of antibiotics were selected and induced in vitro by increasing concentration. The agar dilution method was used to determine the MIC value of each strain before and after induction to compare the ease of induction by Hp to the three antibiotics. Results Seven Hp strains that were sensitive to three kinds of antibiotics were screened out. After six to seven generations of in vitro induction, all seven strains obtained MTZ resistance, three strains obtained resistance to CLA and no AMX resistance. The inducible multiples of Hp against three kinds of antibiotics were different. The majority of MTZ (6/7) was over 32 times, CLA was 1 ~ 256 times, and AMX was 2 ~ 16 times. The MICs of MTZ and CLA were not significantly different from those before passage (P> 0.05), while the MIC of AMX was lower than that before passage (P <0.05) ). Conclusion In vitro induction of Hp infection in children is easy to obtain MTZ resistance, can be obtained CLA resistance, but it is difficult to obtain AMX resistance; consistency in vitro and in vivo experiments suggest that Hp antibiotic resistance is mainly acquired resistance; induced in vitro The ease of occurrence of drug resistance helps predict the change of the actual resistance rate and provide the basis for the selection of antibiotics in the eradication therapy.