Prevalence And Molecular Characterisation Of Group B Streptococcus In Pregnant Women From Hospitals In Ohangwena And Oshikoto Regions Of Namibia

ABSTRACT

BACKGROUND

Group B streptococcus (GBS) naturally colonises the lower gastrointestinal and female genitourinary tract. It poses a great risk of morbidity and mortality to infants born to colonised mothers. It is highly implicated in maternal infections such as endometritis and chorioamnionitis as well as neonatal infections such as pneumonia, meningitis and septicaemia. It also causes stillbirths and miscarriages in colonised women.

Group B streptococcus infection in neonates is classified in two clinical syndromes, which are Early Onset Disease (EOD) and Late Onset Disease (LOD). Early Onset Disease presents between day zero and day seven, and LOD between day eight and day ninetieth (third month) of the infant’s life. GBS is classified into capsular types Ia, Ib and II – IX, based on the polysaccharide capsular antigens of the bacterium. This study aimed at determining the prevalence rate, antimicrobial susceptibility patterns and molecular characteristics of Streptococcus agalactiae isolated from pregnant women at 35 weeks of gestation and above, who attended antenatal screening at selected hospitals in Ohangwena and Oshikoto regions of Namibia.

METHODOLOGY

A descriptive cross-sectional study was conducted from May to September 2018 at selected hospitals. A convenient sampling technique was used to recruit 210 pregnant women at 35+ weeks of gestation. Descriptive data was collected using structured questionnaires. In total, 210 lower vaginal and rectal swabs were collected from participants by trained registered nurses, and were submitted to the laboratory at 2 – 8°C for culture. Swabs were cultured onto 5% sheep blood agar and into Todd-Hewitt broth, both with colistin and nalidixic acid.

Plates were examined for the growth of whitish-grey and translucent colonies with big or narrow zone of beta haemolysis. Probable colonies were identified as GBS using the Christie, Atkins, Munch and Petersen (CAMP) test and polymerase chain reaction (PCR). Antimicrobial sensitivities were determined using Kirby-Bauer disc diffusion method and Vitek 2 methods. Gene based resistance and capsular types were examined using PCR. Statistical analysis was performed using the Pearson’s Chi square test, and a P value < 0.05 was considered statistically significant.