儿童呼吸道肺炎支原体感染耐药现状

Macrolide-Resistance of Mycoplasma Pnuemoniae in Respiratory Tract Infection in Children

目的了解儿童呼吸道感染中肺炎支原体(MP)感染情况、耐药情况及耐药机制。方法选取2008年12月-2009年3月在北京友谊医院儿科门诊就诊的呼吸道感染患儿80例,对所有入选对象取咽拭子,行MP培养,直接对咽拭子及培养阳性标本应用巢式PCR技术扩增23S rRNA基因,并对扩增产物行电泳检测及DNA测序分析;并根据扩增基因测序结果是否有基因突变分为耐药组和敏感组,比较2组患儿在就诊前口服大环内酯类药物情况,门诊与病房MP耐药率是否存在差别。结果直接对咽拭子23S rRNA基因进行巢式PCR扩增、电泳、测序,阳性32例,经MP分离培养阳性并经测序鉴定证实MP 8例,其中1例咽拭子培养结果阳性而直接咽拭子PCR结果阴性,MP阳性总数33例。DNA测序结果与标准株序列相同16例,余17例存在23S rRNA V区碱基点突变:A2063G突变10例,A2064G突变3例,A2067G突变2例,A2063T突变、G2062A突变各1例。2组患儿在就诊前是否口服大环内酯类药物方面无显著性差异(P=0.909),门诊与既往病房MP耐药率亦无显著差异(P=0.459)。结论MP耐药突变位点仍以A2063G突变为主,存在少数A2064G突变,新发现了A2063T、A2067G、G2062A位点突变,可能与耐药相关。

Objective To investigate the mycoplasma pneumoniae（MP） infection of the respiratory tract infection in children,the macrolide - resistant situation and resistance mechanism of MP. Methods The cultured throat swab specimens were obtained from 80 pediatric outpatients with respiratory tract infection from Dec. 2008 to Mar. 2009 in Beijing friendship hospital. The 23S rRNA gene of throat swab speci- mens and positive - cultured specimens were amplified using nested - PCR, and the products were further verified by elcctrophoresis and DNA sepuencing,which were collected from the outpatients. The specimens were divided into 2 groups depending on the findings of the gene se- quencing whether they had gene mutation ： sensitive and resistance group. The DNA sequence of samples were compared to the sequence of MP reference strain in genbank in order to findout MP drug resistant gene. The differences in macrolids therapy were investigated between 2 groups before the throat swab obtained. The drug resistance rates were compared between outpatients and inpatients. Results Thirty - two throat swab specimens were proved to be MP by direct nested -PCR,and 8 throat speeimens were proved to be MP by isolation and cultures. Total 33 cases （including 1 was positive- culture but nagative- direct PCR） were proved to be MP positive. Sixteen were identical to the M129 standard se- quence,and 17 had point mutation in gene of 23S rRNA V region. ＇Fen had A to G mutation at position 2063,3 had A to G mutation at position 2064,2 had A to G mutation at position 2067,1 had G to A mutation at position 2062,1 had A to T mutation at position 2063. There was no sig- nificant difference between the sensitive and resistance group in whether had macrolids before the throat swab obtained（ P = 0. 909 ）. And there was no significant difference in MP drug resistance rate between outpatients and inpatients（P = O. 459）. Conclusions The major mutation were A2063G and A2064G,and A2063T, A2067G, G2062A were newly found mutation points which were possibly related to macrolids resistance.