Antigenic distribution of Streptococcus agalactiae isolates from pregnant women at Garankuwa hospital - South Africa

Martina O Chukwu; Rooyen Tinago Mavenyengwa; Charles M Monyama; John Y Bolukaoto; Sogolo L Lebelo; Motlatji Rb Maloba; Maphoshane Nchabeleng; Sylvester Rogers Moyo

doi:10.11599/germs.2015.1080

Antigenic distribution of Streptococcus agalactiae isolates from pregnant women at Garankuwa hospital - South Africa

Germs. 2015 Dec 2;5(4):125-33. doi: 10.11599/germs.2015.1080. eCollection 2015 Dec.

Authors

Martina O Chukwu¹, Rooyen Tinago Mavenyengwa², Charles M Monyama¹, John Y Bolukaoto¹, Sogolo L Lebelo³, Motlatji Rb Maloba⁴, Maphoshane Nchabeleng⁵, Sylvester Rogers Moyo⁶

Affiliations

¹ MSc, Department of Life and Consumer Science, School of Agriculture and Life Sciences University of South Africa (UNISA), Florida Campus, Pretoria, South Africa.
² MSc, DPhil, Department of Medical Microbiology, University of Zimbabwe College of Health Sciences, Harare, Zimbabwe, Department of Health Sciences, School of Health and Applied Sciences, Polytechnic of Namibia, Windhoek, Namibia.
³ MSc, PhD, Department of Life and Consumer Science, School of Agriculture and Life Sciences University of South Africa (UNISA), Florida Campus, Pretoria, South Africa.
⁴ MD, Department of Microbiological Pathology, University of Limpopo (MEDUNSA), Pretoria, South Africa.
⁵ MD, PhD, Department of Microbiological Pathology, University of Limpopo (MEDUNSA), Pretoria, South Africa.
⁶ MSc, DPhil, Department of Health Sciences, School of Health and Applied Sciences, Polytechnic of Namibia, Windhoek, Namibia.

Abstract

Introduction: Streptococcus agalactiae (group B streptococcus; GBS) is globally recognised as one of the leading causes of neonatal sepsis and meningitis. It also causes adverse pregnancy outcomes such as stillbirth and miscarriages. Incidence of invasive disease is increasing in non-pregnant adults with underlying medical conditions (e.g., diabetes mellitus). Epidemiological studies of GBS infections are based on capsular serotyping. Genotyping of the surface anchored protein genes is also becoming an important tool for GBS studies. Currently ten different GBS serotypes have been identified. This study was performed to determine the prevalence of GBS capsular types (CTs) and surface anchored protein genes in isolates from colonized pregnant women attending antenatal clinic, at Dr George Mukhari Academic Hospital, Garankuwa, Pretoria, South Africa.

Methods: The samples were collected over 11 months and cultured on selective media. GBS was identified using different morphological and biochemical tests. Capsular typing was done using latex agglutination test and conventional PCR. Multiplex PCR with specific primers was used to detect the surface anchored protein genes.

Results: Of the 413 pregnant women recruited, 128 (30.9%) were colonized with GBS. The capsular polysaccharide (CPS) typing test showed that CPS type III (29.7%) was the most prevalent capsular type followed by CPS type Ia (25.8%), II (15.6%), IV (8.6%), V (10.9%) and Ib (8.6%); 0.7% of the isolates were nontypeable. Multiplex PCR revealed that the surface proteins genes were possessed by all the capsular types: rib (44.5%), bca (24.7%), alp2/3 (17.9%), epsilon (8.6%) and alp4 (4.7%).

Conclusion: The common capsular types found in this study are Ia, III, and II. The most common protein genes identified were rib and bca, and the distribution of the surface protein genes among the isolates of different capsular types showed similar trends to the distribution reported from previous studies.

Keywords: Streptococcus agalactiae; pregnancy; serotypes; surface proteins.