北京地区儿童鼻咽部肺炎链球菌对大环内酯类抗生素耐药的检测

目的 研究北京地区儿童携带肺炎链球菌(SP)对大环内酯类抗生素的耐药特点。方法 对2002～2003年上呼吸道感染儿童鼻咽部200株SP分离株对4种大环内酯类抗生素、青霉素和克林霉素的最低抑菌浓度进行检测;耐药诱导试验分析部分耐药菌株大环内酯类耐药表型;PCR检测红霉素耐药基因ermB和mefA。结果 200株SP中179株对红霉素耐药。红霉素和青霉素的药敏结果无明显关连性。耐红霉素的147株SP中,阿奇霉素、克拉霉素、乙酰螺旋霉素和克林霉素的耐药率分别是100％,100％,95．2％,95．9％。耐药表型以结构型大环内酯类、林可酰胺类和链阳性菌素B耐药表型(cMLS)为主,占红霉素耐药株的95．9％。耐药基因检测中,仅携带ermB基因的菌株为79．6％,同时携带ermB和mefA基因菌株为17．7％,仅携带mefA基因的菌株为2．7％。结论 2002～2003年北京上呼吸道感染患儿携带的SP对红霉素耐药率达89．5％,分离株在对红霉素耐药同时也对其他大环内酯类药物和克林霉素耐药。耐大环内酯SP表型以cMLS为主,基因型以ermB为主。

Macrolide-resistant Streptococcus pneumoniae in the pediatric population in Beijing

OBJECTIVE: To analyze the mechanisms of macrolide resistance in Streptococcus pneumoniae from children in Beijing. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.