Yang Hui, Shen Xu-zhuang, Wang Yong-hong, Yuan Lin, Yu Sang-jie, Yang Yong-hong
Laboratory of Microbiology and Immunology, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital University of Medical Sciences, Beijing 100045, China.
Zhonghua Er Ke Za Zhi. 2004 Dec;42(12):936-9.
To analyze the mechanisms of macrolide resistance in Streptococcus pneumoniae from children in Beijing.
The MICs of penicillin and erythromycin were determined by the E-test methods for 200 Streptococcus pneumoniae isolates collected from 2002 to 2003 at Beijing Children's Hospital. MICs of azithrhomycin, clarithromycin, acetylspiramycin and clindamycin for 147 erythromycin-resistant isolates were detected by the agar dilution methods. For phenotyping, macrolide resistance induction tests were used in erythromycin-resistant isolates. PCR was used to determine the presence of the erythromycin-resistant genes.
Of 200 Streptococcus pneumoniae isolates, 89.5% were resistant to erythromycin. In 147 erythromycin-resistant isolates, resistance rates were as follows: azithromycin, 100%; clarithromycin, 100%; acetylspiramycin, 95.2%; and clindamycin, 95.9%. The most common macrolide resistance phenotype was the cMIS phenotype (95.9%), 1.4% had the iMLS phenotype and 2.7% the M phenotype. Erythromycin-resistant isolates were characterized for the underlying resistance genotype, with 79.6% having the ermB genotypes, 17.7% having both ermB and mefA, 2.7% having the mefA, and none having neither ermB nor mefA genotypes.
The rates of carriage of macrolide-resistant Streptococcus pneumoniae by children were high in Beijing during 2002 - 2003. cMLS was the most prevalent phenotype among erythromycin-resistant Streptococcus pneumoniae isolates, and ribosomal modification (ermB gene coded) was the main resistance mechanism against macrolides in Beijing region.
分析北京地区儿童肺炎链球菌对大环内酯类抗生素耐药的机制。
采用E-test法测定2002年至2003年在北京儿童医院收集的200株肺炎链球菌分离株对青霉素和红霉素的最低抑菌浓度（MIC）。采用琼脂稀释法检测147株红霉素耐药分离株对阿奇霉素、克拉霉素、乙酰螺旋霉素和克林霉素的MIC。对于表型分析，对红霉素耐药分离株进行大环内酯类耐药诱导试验。采用聚合酶链反应（PCR）检测红霉素耐药基因的存在情况。
200株肺炎链球菌分离株中，89.5%对红霉素耐药。在147株红霉素耐药分离株中，耐药率如下：阿奇霉素100%；克拉霉素100%；乙酰螺旋霉素95.2%；克林霉素95.9%。最常见的大环内酯类耐药表型是cMIS表型（95.9%），1.4%为iMLS表型，2.7%为M表型。对红霉素耐药分离株的潜在耐药基因型进行了鉴定，79.6%具有ermB基因型，17.7%同时具有ermB和mefA，2.7%具有mefA，无一株既无ermB也无mefA基因型。
2002 - 2003年北京地区儿童肺炎链球菌大环内酯类耐药携带率较高。cMLS是红霉素耐药肺炎链球菌分离株中最常见的表型，核糖体修饰（由ermB基因编码）是北京地区肺炎链球菌对大环内酯类抗生素耐药的主要机制。
