(P461) Characterisation of vaginal Prevotella strains from a cohort of South African individuals with and without bacterial vaginosis

Wednesday, July 26, 2023

16:00 – 18:00 CST

Primary Presenter(s)

Kirsten Welp, BMedSc(Hons) (she/her/hers)

Student
Department of Pathology, Institute of Infectious Disease and Molecular Medicine (IDM), University of Cape Town, South Africa
Cape Town, Western Cape, South Africa

Co-author(s)

BK

Brian Kullin

Division of Medical Virology, Department of Pathology, University of Cape Town
Cape Town, Western Cape, South Africa
LP

Lynthia Paul

Department of Pathology, Institute of Infectious Disease and Molecular Medicine (IDM), University of Cape Town, South Africa ;National Health Laboratory Service (NHLS), Cape Town, South Africa
Cape Town, Western Cape, South Africa
CB

Christina Balle

Department of Pathology, Institute of Infectious Disease and Molecular Medicine (IDM), University of Cape Town, South Africa, United States
HJ

Heather Jaspan

Seattle Children’s’ Research Institute, University of Washington
Seattle, Washington, United States
HG

Hoyam Gamieldien

Institute of Infectious Disease and Molecular Medicine, University of Cape Town, South Africa
JP

Jo-Ann Passmore, n/a

Proffessor
University of Cape Town, Institute of Infectious Disease and Molecular Medicine
Cape Town, Western Cape, South Africa

Background: The burden of bacterial vaginosis (BV) in Sub-Saharan Africa (SSA) is amongst the highest worldwide. The vaginal microbiota in individuals with bacterial vaginosis is associated with adverse health outcomes, including obstetric complications, and increased risk of acquiring sexually transmitted infections (STI) and HIV. Prevotella bivia is an important member of biofilms which form part of the BV ecosystem and a critical driver of vaginal inflammation. However, to date very few isolates have been characterized from SSA

Methods: Prevotella spp. were isolated from lateral wall vaginal swabs obtained from BV-positive and BV-negative individuals participating in a study investigating hormonal contraceptive uptake. Putative isolates were confirmed by Prevotella genus-specific PCR and 16S rRNA gene sequencing and further characterised by whole genome sequencing (WGS). Antimicrobial susceptibility of the strains to standard-of-care (SOC) antibiotics was assessed by E-tests. Additionally, the ability of the strains to form biofilms over 120 hours was assessed and quantified in 96-well microtiter plates using a crystal violet staining procedure.

Results: A total of 37 Prevotella strains were isolated from 33 samples (22 BV-positive, 7-negative and 4 -intermediate); 35 strains were confirmed Prevotella bivia and 2 with a closest match to vaginal Prevotella melaninogenica. Metronidazole and clindamycin (BV SOC antibiotics) resistance was observed in 5.4% (2/37) and 8.41% (3/37) of isolates, respectively. Resistance rates to other antibiotics ranged from 24.33-56.76%. Strains resistant to clindamycin were co-resistant to azithromycin. Antimicrobial resistance (AMR) genes were detected in some strains: nimK (1/36), nimI (8/39) and ermF (1/36). The ability to form biofilms varied significantly (p < 0.0001) between isolates. Strains from the same sample, in two separate cases, showed significant difference in biofilm biomass (p=0.0214 and p=0.0466).

Conclusion: This study provides important phenotypic data from Prevotella strains isolated from South African individuals. Although resistance rates to metronidazole and clindamycin were relatively low, the presence of nim and erm genes poses a risk to develop resistance to metronidazole and clindamycin and the potential for horizontal gene transfer to other members of the vaginal microbiota. Strains were differentially able to form biofilms, and intra-sample variability in biofilm formation suggests population-level, inter-strain diversity.