重庆地区肺炎儿童下呼吸道卡他莫拉菌分离株耐药基因研究

Study on the gene of antimicrobitic resistance of Moraxella catarrhalis isolated from lower respiratory tract of children with pneumonia in Chongqing area

目的探讨重庆地区儿童卡他莫拉菌(Moraxella catarrhalis,Mc)分离株对β-内酰胺类抗生素的耐药机制,指导临床合理用药,有利于防止诱导该菌耐药性变迁。方法取2006年6—12月住院的肺炎患儿下呼吸道中分离的β-内酰胺酶阳性Mc40株,采用PCR技术扩增其基因组DNA,经限制性内切酶酶切后,行琼脂糖凝胶电泳,分析Mc的耐药基因表达及分型,同时比较不同基因型的临床特点。结果40株β-内酰胺酶阳性卡他莫拉菌的BRO基因型为:36株(90.0%)BRO-1基因阳性,3株(7.5%)BRO-2基因阳性,1株(2.5%)未检测到BRO-1基因和BRO-2基因。BRO-1基因阳性菌对多数β-内酰胺类抗生素的抑菌圈直径小于BRO-2基因阳性菌株。结论重庆地区儿童Mc的产酶株以BRO-1基因为主,少数为BRO-2基因,极少菌株可能为其他型别。

Objective To explore the mechanism of resistance to beta-lactam antibiotics of Moraxella catarrhalis（Mc） in children with lower respiratory tract infection,to guide the rational and objective administration and provide measures of avoiding changes of antimicrobial resistance of Mc.Methods Total 40 strains Mc with positive beta-lactamase were taken from lower respiratory tract of hospitalized children with pneumonia from July to December in 2006.Polymerase chain reaction technology was used to amplify genes.The DNA product of the 40 strains were digested by restriction enzyme（BCgΙ）.The expression and type of the drug resistance gene（BRO） for ampicillin according to different strap in agarose gel electrophoresis were analyzed.Clinical characteristics of different genotype was studied.Results Among 40 strains Mc with positive Nitrocefin disk,positive BRO-1 gene was 90.0% while positive BRO-2 gene was 7.5%,and another 2.5% was neither positive BRO-1 gene nor positive BRO-2 gene.BRO-3 or TEM-1 enzyme produced may be the possible cause.The diameter of inhibition zone to beta-lactam antibiotics of Mc was smaller in positive BRO-1 gene than that Mc of positive BRO-2 gene.Conclusions BRO-1 gene was the main genotype of Mc with beta-lactamase positive in our study.