Ghamari Mahsa, Jabalameli Fereshteh, Emaneini Mohammad, Beigverdi Reza
Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Medical Mycology and Bacteriology Research Center, Kerman University of Medical Sciences, Kerman, Iran.
New Microbes New Infect. 2022 Jan 17;45:100957. doi: 10.1016/j.nmni.2022.100957. eCollection 2022 Jan.
Group B Streptococcus (GBS or ) is an important pathogen causing severe invasive diseases in neonates, pregnant women, and adults with underlying medical conditions.
To investigate the incidence of resistance to macrolide, lincosamide and streptogramin type B (MLS antibiotics, macrolide and tetracycline resistance determinants and genetic relationships, a total of 146 clinical isolates of GBS were collected from Tehran, Iran. The genetic relationships between erythromycin-resistant strains were determined by multilocus variable tandem repeat analysis (MLVA).
All isolates were susceptible to penicillin, vancomycin, linezolid, and quinupristin-dalfopristin, but were resistant to tetracycline (96.6%, 141/146), erythromycin (28.1%, 41/146) and clindamycin (16.4%, 24/146). Among the 41 erythromycin-resistant GBS (ERGBS), the most common antimicrobial resistance gene was detected in 92.7% (38/41) of the isolates followed by and found in 65.8% (27/41) and 29.3% (12/41) of isolates, respectively. Of the 41 ERGBS, 95% (39/41) exhibited the constitutive MLS phenotype, 2.4% (1/41) displayed inducible MLS and 2.4% (1/41) had M phenotype. The methylase genes were widely related to MLS phenotype isolates, while the gene was associated with M phenotype. MLVA analysis performed on the 41 ERGBS revealed that 34 MLVA types (MTs). MLVA analysis showed that infections due to ERGBS have been caused by a variety of genotypes, suggesting that ERGBS were clonally unrelated and dissemination of these isolates was not due to a clonal outbreak.
Careful usage of macrolide antibiotics in therapy, continued surveillance of resistance rate and appropriate infection control measures can help to reduce spreading of resistance isolates.
B族链球菌（GBS或无乳链球菌）是导致新生儿、孕妇及有基础疾病的成人发生严重侵袭性疾病的重要病原体。
为调查B族链球菌对大环内酯类、林可酰胺类和B型链阳菌素（MLS抗生素）的耐药发生率、大环内酯类和四环素类耐药决定因素及遗传关系，从伊朗德黑兰共收集了146株GBS临床分离株。采用多位点可变串联重复序列分析（MLVA）确定红霉素耐药菌株之间的遗传关系。
所有分离株对青霉素、万古霉素、利奈唑胺和奎奴普丁-达福普汀敏感，但对四环素（96.6%，141/146）、红霉素（28.1%，41/146）和克林霉素（16.4%，24/146）耐药。在41株红霉素耐药GBS（ERGBS）中，最常见的抗菌耐药基因在92.7%（38/41）的分离株中检测到，其次分别在65.8%（27/41）和29.3%（12/41）的分离株中检测到和。在41株ERGBS中，95%（39/41）表现为组成型MLS表型，2.4%（1/41）表现为诱导型MLS，2.4%（1/41）具有M表型。甲基化酶基因与MLS表型分离株广泛相关，而基因与M表型相关。对41株ERGBS进行的MLVA分析显示有34种MLVA类型（MTs）。MLVA分析表明，ERGBS感染由多种基因型引起，提示ERGBS在克隆上无相关性，这些分离株的传播并非由于克隆性暴发。
在治疗中谨慎使用大环内酯类抗生素、持续监测耐药率以及采取适当的感染控制措施有助于减少耐药菌株的传播。
