Vaginal microbiota in women with spontaneous preterm labor versus those with term labor in Kenya: a case control study

Abstract

Background Preterm birth is a global problem with about 12% of births in sub-Saharan Africa occurring before 37 weeks of gestation. Several studies have explored a potential association between vaginal microbiota and preterm birth, and some have found an association while others have not. We performed a study designed to determine whether there is an association with vaginal microbiota and/or placental microbiota and preterm birth in an African setting. Methods Women presenting to the study hospital in labor with a gestational age of 26 to 36 weeks plus six days were prospectively enrolled in a study of the microbiota in preterm labor along with controls matched for age and parity. A vaginal sample was collected at the time of presentation to the hospital in active labor. In addition, a placental sample was collected when available. Libraries were constructed using PCR primers to amplify the V6/V7/V8 variable regions of the 16S rRNA gene, followed by sequencing with an Illumina MiSeq machine and analysis using QIIME2 2022.2. Results Forty-nine women presenting with preterm labor and their controls were enrolled in the study of which 23 matched case–control pairs had sufficient sequence data for comparison. Lactobacillus was identified in all subjects, ranging in abundance from < 1% to > 99%, with Lactobacillus iners and Lactobacillus crispatus the most common species. Over half of the vaginal samples contained Gardnerella and/or Prevotella; both species were associated with preterm birth in previous studies. However, we found no significant difference in composition between mothers with preterm and those with full-term deliveries, with both groups showing roughly equal representation of different Lactobacillus species and dysbiosis-associated genera. Placental samples generally had poor DNA recovery, with a mix of probable sequencing artifacts, contamination, and bacteria acquired during passage through the birth canal. However, several placental samples showed strong evidence for the presence of Streptococcus species, which are known to infect the placenta. Conclusions The current study showed no association of preterm birth with composition of the vaginal community. It does provide important information on the range of sequence types in African women and supports other data suggesting that women of African ancestry have an increased frequency of non-Lactobacillus types, but without evidence of associated adverse outcomes.

Microbiota dynamics, metabolic and immune interactions in the cervicovaginal environment and their role in spontaneous preterm birth

“…The cervicovaginal environment of approximately 16% of pregnant women in Pemba Island, Tanzania, are colonized by at least three of four STI (sexually transmitted infection) infectious agents (i.e., Chlamydia trachomatis , Trichomonas vaginalis , Neisseria gonorrhoeae , and Mycoplasma genitalium ); therefore, adverse pregnancy outcomes may not necessarily be instigated by a single infectious agent ( 79 ). In Kenya, more than fifty percent of the vaginal microbiota consisted of Gardnerella and/or Prevotella , with lactobacilli ranging from 1% – 99%, but without a clear link between variation in composition and term or sPTB ( 94 ). In a longitudinal study involving pregnant Nigerian women (n=38), the prevalent cervicovaginal bacterium was L. iners ( 40 ).…”

The Maternal Microbiome and Gestational Diabetes Mellitus: Cause and Effect

“…These findings suggest that the diversity of the vaginal microbiome may play a role in the risk of preterm birth, were women with decreased levels of protective bacterial species and increased levels of harmful bacteria may be at greater risk. In contrast to these findings, a study conducted in an African population showed no association between preterm birth and the composition of the vaginal community [ 93 ]. Differences observed between these studies may be due to sample size and ethnicity.…”

“…These findings emphasize the need for dental hygiene as an integral component of prenatal care. Recently, the placental microbiome has been associated with preterm birth [ 95 , 96 ], although conflicting findings exist [ 93 , 97 ]. Discrepancies observed between studies may be due to difficulty in recovering viable DNA samples from the placenta or the detection of low bacterial loads that are indistinguishable from negative controls or potential sources of contaminants.…”

Antibiotic-free vaginal microbiota transplant with donor engraftment, dysbiosis resolution and live birth after recurrent pregnancy loss: a proof of concept case study

“…VD is a severe challenge worldwide in women’s health leading to infertility, pregnancy loss and major obstetrical complications such as PPROM and preterm labor. 7 , 8 , 24 Moreover, due to high recurrence rates and increasing resistance to antibiotics, there is a need to develop alternative and durable treatments for this condition. 1 , 12 , 13 Ideally, a therapy without the use of antibiotics could prove to be a better and potentially more sustainable solution.…”