Zakerifar Mona, Goli Hamid Reza, Kaboosi Hami, Rahmani Zahra, Peyravii Ghadikolaii Fatemeh
Department of Microbiology, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran.
Molecular and Cell Biology Research Centre, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari, Iran.
AMB Express. 2024 Jan 28;14(1):13. doi: 10.1186/s13568-024-01671-x.
Streptococcus agalactiae has different virulence factors, from which the capsule has the most significant role in the pathogenesis of this organism. We aimed to investigate the distribution of more prevalent capsular genes among different Random Amplified Polymorphic DNA (RAPD) types of S. agalactiae isolated from pregnant women. A total of 106 isolates were collected from 420 vaginal and rectal swabs obtained from pregnant women. The specimens were transferred using Todd Hewitt Broth and were cultured on a blood agar containing antibiotics. The S. agalactiae isolates were identified by the standard microbiological and biochemical tests. The genomic DNAs of S. agalactiae isolates were extracted using an extraction kit. Then, the PCR method was used to detection of the capsular genes. Moreover, The RAPD PCR was used to genotyping of the isolates. The colonization rate of the pregnant women was 25.23%, and there was a statistically significant correlation between the weeks of gestation and the probability of colonization (p-value < 0.05). Also, 31 (29.24%) and 18 (16.98%) pregnant women had a history of abortion and membrane rupture, respectively. In addition, 20 (18.86%), 32 (30.18%), 4 (3.77%), and 6 (5.66%) isolates carried genes encoding capsular types Ia, Ib, III, and V, respectively. None isolates had the type II capsular gene, and other 44 isolates were non-typeable. Nine clones (clusters) of S. agalactiae were observed in the present study with 70% similarity, and 53 different types were identified among the isolates. Except for capsular types III and V that belonged to clones 3, 5, 7, and 9, other capsular types were detected in different RAPD types. We found that the capsular types Ib and Ia were predominant among pregnant women in this area, indicating their significance for vaccine designation. Also, our isolates showed a lower genotypic diversity in RAPD typing. This may be due to the same sources of most isolates.
无乳链球菌具有不同的毒力因子，其中荚膜在该菌的致病机制中作用最为显著。我们旨在研究从孕妇分离出的不同随机扩增多态性DNA（RAPD）类型的无乳链球菌中更常见的荚膜基因的分布情况。从420份孕妇阴道和直肠拭子中总共收集了106株分离株。标本用托德-休伊特肉汤转运，并在含抗生素的血琼脂上培养。通过标准的微生物学和生化试验鉴定无乳链球菌分离株。使用提取试剂盒提取无乳链球菌分离株的基因组DNA。然后，采用PCR方法检测荚膜基因。此外，用RAPD-PCR对分离株进行基因分型。孕妇的定植率为25.23%，妊娠周数与定植概率之间存在统计学显著相关性（p值<0.05）。此外，分别有31名（29.24%）和18名（16.98%）孕妇有流产和胎膜破裂史。另外，分别有20株（18.86%）、32株（30.18%）、4株（3.77%）和6株（5.66%）分离株携带编码Ia、Ib、III和V型荚膜的基因。没有分离株携带II型荚膜基因，其他44株分离株无法分型。在本研究中观察到9个无乳链球菌克隆（簇），相似度为70%，在分离株中鉴定出53种不同类型。除了属于克隆3、5、7和9的III型和V型荚膜外，其他荚膜类型在不同的RAPD类型中被检测到。我们发现Ib型和Ia型荚膜在该地区孕妇中占主导地位，表明它们对疫苗设计的重要性。此外，我们的分离株在RAPD分型中显示出较低的基因型多样性。这可能是由于大多数分离株来源相同。
