Servicio de Bacteriología, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda, Madrid, Spain.
BMC Microbiol. 2012 Sep 21;12:215. doi: 10.1186/1471-2180-12-215.
Group A Streptococcus (GAS) causes human diseases ranging in severity from uncomplicated pharyngitis to life-threatening necrotizing fasciitis and shows high rates of macrolide resistance in several countries. Our goal is to identify antimicrobial resistance in Spanish GAS isolates collected between 1994 and 2006 and to determine the molecular epidemiology (emm/T typing and PFGE) and resistance mechanisms of those resistant to erythromycin and tetracycline.
Two hundred ninety-five out of 898 isolates (32.8%) were erythromycin resistant, with the predominance of emm4T4, emm75T25, and emm28T28, accounting the 67.1% of the 21 emm/T types. Spread of emm4T4, emm75T25 and emm28T28 resistant clones caused high rates of macrolide resistance. The distribution of the phenotypes was M (76.9%), cMLSB (20.3%), iMLSB (2.7%) with the involvement of the erythromycin resistance genes mef(A) (89.5%), msr(D) (81.7%), erm(B) (37.3%) and erm(A) (35.9%).Sixty-one isolates were tetracycline resistant, with the main representation of the emm77T28 among 20 emm/T types. To note, the combination of tet(M) and tet(O) tetracycline resistance genes were similar to tet(M) alone reaching values close to 40%. Resistance to both antibiotics was detected in 19 isolates of 7 emm/T types, being emm11T11 and the cMLSB phenotype the most frequent ones. erm(B) and tet(M) were present in almost all the strains, while erm(A), mef(A), msr(D) and tet(O) appeared in less than half of them.
Spanish GAS were highly resistant to macrolides meanwhile showed minor resistance rate to tetracycline. A remarkable correlation between antimicrobial resistance and emm/T type was noticed. Clonal spread of emm4T4, emm75T25 and emm28T28 was the main responsable for macrolide resistance where as that emm77T28 clones were it to tetraclycline resistance. A wide variety of macrolide resistance genes were responsible for three macrolide resistance phenotypes.
A 组链球菌（GAS）可引起从轻度咽炎到致命坏死性筋膜炎等多种人类疾病，并且在多个国家表现出高比例的大环内酯类耐药性。我们的目标是确定 1994 年至 2006 年间收集的西班牙 GAS 分离株的抗菌药物耐药性，并确定对红霉素和四环素耐药的菌株的分子流行病学（emm/T 型和 PFGE）和耐药机制。
898 株分离株中有 295 株（32.8%）对红霉素耐药，其中 emm4T4、emm75T25 和 emm28T28 占主导地位，占 21 种 emm/T 型的 67.1%。emm4T4、emm75T25 和 emm28T28 耐药克隆的传播导致大环内酯类药物耐药率高。表型分布为 M（76.9%）、cMLSB（20.3%）、iMLSB（2.7%），涉及红霉素耐药基因 mef(A)（89.5%）、msr(D)（81.7%）、erm(B)（37.3%）和 erm(A)（35.9%）。61 株对四环素耐药，20 种 emm/T 型中主要代表 emm77T28。值得注意的是，tet(M)和 tet(O)四环素耐药基因的组合与单独的 tet(M)相似，接近 40%。在 7 种 emm/T 型的 19 株菌中检测到对两种抗生素的耐药性，其中 emm11T11 和 cMLSB 表型最为常见。erm(B)和 tet(M)几乎存在于所有菌株中，而 erm(A)、mef(A)、msr(D)和 tet(O)则不到一半。
西班牙 GAS 对大环内酯类药物高度耐药，同时对四环素的耐药率较低。抗菌药物耐药性与 emm/T 型之间存在显著相关性。emm4T4、emm75T25 和 emm28T28 的克隆传播是大环内酯类耐药的主要原因，而 emm77T28 克隆则是导致四环素耐药的原因。多种大环内酯类耐药基因导致了三种大环内酯类耐药表型。
