Streptococcus agalactiae, also known as group B Streptococcus, is an aetiological agent of urinary tract infection (UTI) in adults, including cystitis, pyelonephritis and asymptomatic bacteriuria (ABU). Whereas ABU-causing S. agalactiae (ABSA) have been shown to grow and achieve higher culture denstity in human urine compared to uropathogenic S. agalactiae (UPSA) other phenotypic distinctions between S. agalactiae isolated from different forms of UTI are not known. Here, we define the hemolytic activities and biofilm-formation of a collection of clinical isolates of UPSA, ABSA and recurrent S. agalactiae bacteriuria (rSAB) strains to explore these phenotypes in the context of clinical history of isolates. A total of 61 UPSA, 184 ABSA, and 47 rSAB isolates were analyzed for relative hemolytic activity by spot assay on blood agar, which was validated using a erythrocyte lysis suspension assay. Biofilm formation was determined by microtiter plate assay with Lysogeny and Todd-Hewitt broths supplemented with 1% glucose to induce biofilm formation. We also used multiplex PCR to analyze isolates for the presence of genes encoding adhesive pili, which contribute to biofilm formation. Comparing the hemolytic activities of 292 isolates showed, surprisingly, that ABSA strains were significantly more likely to be highly hemolytic compared to other strains. In contrast, there were no differences between the relative abilities of strains from the different clinical history groups to form biofilms. Taken together, these findings demonstrate a propensity of S. agalactiae causing ABU to be highly hemolytic but no link between clinical history of UTI strains and ability to form biofilm.

无乳链球菌，也称为 B 组链球菌，是成人尿路感染 (UTI) 的病原体，包括膀胱炎、肾盂肾炎和无症状菌尿 (ABU)。尽管与尿路致病性无乳链球菌(UPSA)相比，导致 ABU 的无乳链球菌(ABSA) 已被证明在人类尿液中生长并达到更高的培养密度，但从不同形式的 UTI 中分离出的无乳链球菌之间的其他表型差异尚不清楚。在这里，我们定义了一组 UPSA、ABSA 和复发性无乳链球菌的临床分离株的溶血活性和生物膜形成菌尿 (rSAB) 菌株以在分离株的临床历史背景下探索这些表型。通过血琼脂上的点检测分析了总共 61 个 UPSA、184 个 ABSA 和 47 个 rSAB 分离株的相对溶血活性，并使用红细胞裂解悬浮液检测进行了验证。生物膜形成通过微量滴定板测定法测定，其中溶原性和 Todd-Hewitt 肉汤补充有 1% 葡萄糖以诱导生物膜形成。我们还使用多重 PCR 来分析分离株中是否存在编码粘附菌毛的基因，这有助于生物膜形成。比较 292 个分离株的溶血活性，令人惊讶的是，与其他菌株相比，ABSA 菌株更可能具有高度溶血性。相比之下，来自不同临床病史组的菌株形成生物膜的相对能力之间没有差异。综上所述，这些发现表明无乳链球菌导致 ABU 高度溶血，但 UTI 菌株的临床病史与形成生物膜的能力之间没有联系。