隔夜管网水中细菌对典型抗生素的耐药性研究

Antibiotic resistance of bacteria in tap water stored in water supply distribution system overnight

目的研究滞留过夜对管网水中细菌抗生素耐药性的影响。方法以实际管网水为研究对象,通过考察总异养菌数、抗性界定浓度下抗性菌数量和比例,分析滞留0 h和12 h时管网水中的细菌对不同浓度青霉素、四环素、头孢氨苄、环丙沙星、阿奇霉素和庆大霉素6种抗生素的耐受性。结果在滞留时间为0 h时,当抗生素在较低浓度时,耐药性细菌数量和比例处于较高水平;在滞留12 h的水样中,除庆大霉素外,环丙沙星、四环素、青霉素、头孢霉素和阿奇霉素,在浓度为4 mg/L时,就已经具有良好的抑菌效果,耐药性细菌的数量和比例分别为52、52、21、46、38 CFU/100 ml和30.6%、30.4%、12.1%、26.9%、22.1%。与滞留0 h比较,滞留12 h的水样中,6种抗生素对细菌的半抑制浓度均下降。结论滞留12 h的管网水总异养菌群对抗生素的敏感性增强。

Objective To explore the antibiotic resistance of bacteria in tap water stored in water supply pipe network overnight.Methods The total heterotrophic bacteria, antibiotic-resistant bacteria ratio, and concentration were analyzed in tap water stored in actual water supply pipe network for 0 h and 12 h respectively.The resistance to penicillin, tetracycline,cephalosporins, ciprofloxacin, azithromycin and gentamicin with different concentrations were examined for bacteria in water samples. Results In tap water stored in pipe network for 0 h, the number and proportion of antibiotic-resistant bacteria resistant to antibiotics with lower concentration were still in higher level. In overnight water samples, 4 mg/L ciprofloxacin,tetracycline, penicillin, cefotaxime prime and azithromycin, except for gentamicin,showed perfect bacteriostasis effect, the number and proportion of antibiotic-resistant bacteria were 52, 52, 21, 46, 38 CFU/100 ml and 30.6% and 30.4%, 12.1%,26.9% and 22.1% respectively. The levels of IC50 of six antibiotics for bacteria in water samples stored in pipe work for 12 h decreased compared with those for 0 h. Conclusion The total heterotrophic bacteria in water samples stored in water supply pipe network overnight presents higher sensitivity to antibiotics.