Association between serum zinc level and dynamics of Group B Streptococcus colonisation among pregnant women in South Africa
Date
2024
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of the Witwatersrand, Johannesburg
Abstract
Background
Maternal colonisation by Group B Streptococcus (GBS) is a major risk factor for early onset invasive GBS disease among newborns. Zinc micronutrient plays a critical role in several biological processes that are essential to prevent bacterial colonisation and/or invasion. The aim of this study was to investigate the association of serum zinc levels with GBS rectovaginal new acquisition and clearance from 20 to 37+ weeks gestation in pregnant women.
Methods
Vaginal and rectal GBS colonisation was determined at 20–25 weeks (visit-1), followed by 3 subsequent visits at 5–6 weeks intervals, until 37–40 weeks gestation (visit-4). Serum was collected at visit-1 and visit-4 and serum zinc was estimated by inductively coupled plasma mass spectrometry. “New acquisition” group was defined as participants for whom GBS culture was negative at visit-1 and acquired GBS in one of the subsequent visits. Participants not colonised with GBS at any visits were categorized as GBS “persistently uncolonised”. Participants who remained colonised throughout all study visits were defined as “persistently
colonised” group. GBS “clearance group” included participants who were colonised at enrolment (visit-1) and in whom GBS colonisation cleared by last visit (visit-4).
Results
Participants in persistently un-colonised group had significantly higher zinc geometric mean concentration (GMC) at visit-1 compared with those who had new acquisition (20.18 µmol/L; 95%CI 17.99-22.64 vs 13.68 µmol/L; 95%CI 12.59-14.87, p=0.03). Higher zinc concentration in the persistently un-colonised group when compared with new acquisition group was significantly associated with lower odds of GBS rectovaginal acquisition [Odds ratio (OR) 0.15, p=0.001]. The lowest zinc threshold significantly associated with 45% lower odds of new acquisition was ≥15 umol/L (27.2% in new acquisition vs 40.5% in persistently un-colonised; OR 0.55; 95%CI 0.31- 0.96; p=0.03). Furthermore, zinc concentration was higher among women in clearance group compared with those in persistently colonised group
(20.03 µmol/L; 95%CI 16.54-24.27 vs 16.45 µmol/L; 95%CI 13.32-20.31, p=0.04).
Conclusion
There was an inverse association between serum zinc levels in pregnant women and odds of GBS acquisition in those not initially colonised. Zinc supplementation in early pregnancy could reduce risk of invasive GBS disease in their newborns
Description
A research report submitted n partial fulfillment of the requirements for the degree of Master of Public Health 2024 to the Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, Johannesburg, 2024
Keywords
UCTD, Group B Streptococcus, Zinc, Pregnant women
Citation
Dhar, Nisha. (2024). Association between serum zinc level and dynamics of Group B Streptococcus colonisation among pregnant women in South Africa [Master’s dissertation, University of the Witwatersrand, Johannesburg]. WireDSpace. https://hdl.handle.net/10539/42701