Abstract
IntroductionPrevious studies have shown that alterations of the bacterial microbiota in the lower female genital tract influence susceptibility to HIV infection and shedding. We assessed geographic differences in types of genital microbiota between HIV-infected and uninfected women from Rwanda and the United States.MethodsGenera of lower genital tract bacterial microbiota were identified by high-throughput pyrosequencing of the 16S rRNA gene from 46 US women (36 HIV-infected, 10 HIV-uninfected) and 40 Rwandan women (18 HIV-infected, 22 HIV-uninfected) with similar proportions of low (0–3) Nugent scores. Species of Lactobacillus were identified by assembling sequences along with reference sequences into phylogenetic trees. Prevalence of genera and Lactobacillus species were compared using Fisher's exact tests.ResultsOverall the seven most prevalent genera were Lactobacillus (74%), Prevotella (56%), Gardnerella (55%), Atopobium (42%), Sneathia (37%), Megasphaera (30%), and Parvimonas (26%), observed at similar prevalences comparing Rwandan to US women, except for Megasphaera (20% vs. 39%, p = 0.06). Additionally, Rwandan women had higher frequencies of Mycoplasma (23% vs. 7%, p = 0.06) and Eggerthella (13% vs. 0%, p = 0.02), and lower frequencies of Lachnobacterium (8% vs. 35%, p<0.01) and Allisonella (5% vs. 30%, p<0.01), compared with US women. The prevalence of Mycoplasma was highest (p<0.05) in HIV-infected Rwandan women (39%), compared to HIV-infected US women (6%), HIV-uninfected Rwandan (9%) and US (10%) women. The most prevalent lactobacillus species in both Rwandan and US women was L. iners (58% vs. 76%, p = 0.11), followed by L. crispatus (28% vs. 30%, p = 0.82), L. jensenii (20% vs. 24%, p = 0.80), L. gasseri (20% vs. 11%, p = 0.37) and L. vaginalis (20% vs. 7%, p = 0.10).DiscussionWe found similar prevalence of most major bacterial genera and Lactobacillus species in Rwandan and US women. Further work will be needed to establish whether observed differences differentially impact lower genital tract health or susceptibility to genital infections.
Highlights
Previous studies have shown that alterations of the bacterial microbiota in the lower female genital tract influence susceptibility to HIV infection and shedding
All CVL samples were gently vortexed to evenly distribute cells before they were aliquotted; Rwandan Women’s Interassociation Study and Assessment (RWISA) CVL samples were processed within 2 hours of collection and Women’s Interagency HIV Study (WIHS) CVL samples were held on ice until processing within 6 hours of collection
Specimens from Rwandan women were collected before wide antiretroviral medication (ART) availability in Rwanda and between January 1995 and April 1997 for United States (US) women, when ART use was not yet optimal
Summary
Previous studies have shown that alterations of the bacterial microbiota in the lower female genital tract influence susceptibility to HIV infection and shedding. Many reproductive-aged women have lower genital tract microbiota that can be classified as either "healthy" microbiota or bacterial vaginosis (BV) [1,2,3,4,5,6]. While healthy microbiota generally are comprised mostly of Lactobacillus spp., in different women L. crispatus, L. iners, L. jensenii or L. gasseri can be the dominant species [7,8,9]and there are significant differences in the beneficial effects of each [10,11,12,13,14,15,16]. A substantial heterogeneity in BV has been confirmed in other recent studies using molecular-based methods [7,17]
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