Laboratorio de Inmunoquímica y Biotecnología, CIVETAN (CONICET), Facultad de Ciencias Veterinarias, Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPBA), 7000, Tandil, Argentina.
Servicio Neumotisiología, Nueva Clínica Chacabuco, 7000, Tandil, Argentina.
Curr Microbiol. 2022 Nov 3;79(12):392. doi: 10.1007/s00284-022-03050-w.
Streptococcus agalactiae (GBS) is a colonizing agent in pregnant women, the main cause of invasive neonatal infections, and the reason of serious diseases in non-pregnant adults. Several virulence determinants are involved in the pathogenesis. These include capsular polysaccharide, surface-localized proteins, and toxins. Penicillin is considered the first choice antibiotic for the treatment and prophylaxis; erythromycin, clindamycin and fluoroquinolones are recommended alternatives for penicillin-allergic GBS carriers or patients. Our objective was to investigate the virulence genetic characteristics and the antimicrobial susceptibility of 162 GBS colonizing and infective isolates recovered in Argentina. Serotypes Ia and III were the most prevalent ones, followed by Ib, II, V, IV and non-typeable. In relation to the 13 virulence genes screened, cpsA, cylE, hylB, lmb, and scpB were the most prevalent and could be postulated as vaccine epitopes; bca, rib, bac, hvgA, spb1, PI, PI-2a, and PI-2b were detected in lesser frequencies. No significant association was found between serotypes or virulence genes and colonizing or infective isolates but, on the contrary, significant association was observed between some genes and the most prevalent serotypes, la and III. The cluster analysis showed 52 virulence profiles and, antimicrobial resistance tests, 16 profiles, some with up to 4 resistances. Tetracycline resistance was significantly associated with colonizing isolates. Genes tetM and ermB conferring resistance to tetracyclines and macrolides, respectively, were the most commonly identified. Our findings show that GBS colonizing and infective isolates circulating in Argentina share similar features in terms of serotype and virulence genes and show a high level of antimicrobial resistance.
无乳链球菌（GBS）是孕妇定植菌，是侵袭性新生儿感染的主要原因，也是非妊娠成年人严重疾病的原因。一些毒力决定因素参与了发病机制。这些包括荚膜多糖、表面定位蛋白和毒素。青霉素被认为是治疗和预防的首选抗生素；对于青霉素过敏的 GBS 携带者或患者，推荐使用红霉素、克林霉素和氟喹诺酮类药物作为替代药物。我们的目的是研究在阿根廷分离的 162 株定植和感染的无乳链球菌的毒力遗传特征和抗菌药物敏感性。血清型 Ia 和 III 是最常见的，其次是 Ib、II、V、IV 和非定型。在筛选的 13 个毒力基因中，cpsA、cylE、hylB、lmb 和 scpB 最为常见，可以作为疫苗表位；bca、rib、bac、hvgA、spb1、PI、PI-2a 和 PI-2b 的检出频率较低。血清型或毒力基因与定植或感染分离株之间没有显著相关性，但相反，某些基因与最常见的血清型 Ia 和 III 之间存在显著相关性。聚类分析显示了 52 种毒力谱，抗菌药物耐药性测试显示了 16 种谱，其中一些具有多达 4 种耐药性。四环素耐药与定植分离株显著相关。分别赋予四环素和大环内酯类药物耐药性的 tetM 和 ermB 基因是最常见的识别基因。我们的研究结果表明，在阿根廷流行的无乳链球菌定植和感染分离株在血清型和毒力基因方面具有相似的特征，并表现出高水平的抗菌药物耐药性。
