Objective The protective role of Lactobacillus iners in the vaginal microbiota has been questioned. Recent studies have shown that L. iners is the dominating taxon in a large subset of women worldwide. The aim of this study was to identify sociodemographic, behavioural and clinical variables associated with L. iners-dominated community state type (CST) III in Brazilian women of reproductive age.
Participants and methods This study leveraged microbiota compositional data generated by sequencing of the V3-V4 16S rRNA gene from vaginal samples collected from 442 participants enrolled in a previous cross-sectional study that included 609 women in five geographical regions of Brazil. A total of 167 (27.4%) participants were excluded from the current study as they did not present a Lactobacillus-dominated vaginal microbiota. Data on sociodemographic and behavioural characteristics of the study population were obtained through face-to-face interviews. Participants were assigned to two study groups: those with L. iners-dominated CST III (n=222) and those with three distinct CSTs (I, II or V) dominated by another Lactobacillus spp. (n=220). Logistic regression analysis using a stepwise method was performed to test association between CST III and participants’ characteristics, considering their OR and 95% CIs.
Results Among the population characteristics assessed, L. iners-dominated CST III was independently associated with having two or more sexual partners (OR 3.27; 95% CI 1.50 to 7.11) and microscopic detection of Candida sp. on vaginal smears (OR 2.24; 95% CI 1.02 to 4.89). Other characteristics were inversely associated with CST III, including condom use (OR 0.59; 95% CI 0.38 to 0.91), higher educational level (OR 0.61; 95% CI 0.41 to 0.91) and diet containing milk/dairy intake (OR 0.43; 95% CI 0.20 to 0.90).
Conclusion Unprotected sex practices, number of sexual partners and lower educational levels may be useful for identifying women with L. iners-dominated microbiota and its suboptimal protective properties. L. iners microbiota does not seem to provide optimal protection against Candida sp. colonisation, warranting further investigation.
- bacterial infections
- molecular biology
- vaginal smears
- sexual behaviour
Data availability statement
No data are available. Not available.
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Handling editor Francesca Ceccherini-Silberstein
Contributors CM and MGS designed the study. CSTF, ART and CM lead the clinical study and biological sample collection. JN, CM and CSTF performed laboratory analysis. JR and BM obtained and processed sequencing data. JN and CM conducted the statistical analysis and interpreted the data. JN drafted the manuscript under the supervision of CM and MGS. JR and AdRT edited the manuscript. All authors reviewed and approved the submitted version of the manuscript.
Funding This study has received funding by developmental funds granted by São Paulo Research Foundation − FAPESP (grant number 2012/16800-3) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior − Brasil − CAPES (Master’s scholarship number 1680048).
Disclaimer The sponsor not been involved in the conduct of the research or the preparation of the article.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
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