Impact of asymptomatic genital tract infections on in vitro Fertilization (IVF) outcome

PLoS One. 2018 Nov 16;13(11):e0207684. doi: 10.1371/journal.pone.0207684. eCollection 2018.


Background: Infertility is estimated to affect approximately 9-30% of reproductive-aged couples. Several conditions involving one or both partners may contribute to infertility. The aim of this study is to evaluate the role of asymptomatic genital tract infections in the outcome of In Vitro Fertilization (IVF) in couples with infertility.

Methods: A total of 285 infertile couples were enrolled in the study. Vaginal/endocervical swabs and semen samples were collected and subjected to microbiological analysis. Spermiograms were carried out on semen specimens, and lactobacilli were quantified in vaginal swabs. Data were associated with IVF results and analysed by using non parametric tests and multivariate analysis.

Results: Microbiological analysis showed that 46.3% of couples presented with an asymptomatic genital tract infection. Spermiogram results showed a significantly diminished motility of sperm cells in samples positive to microbiological testing compared to negative specimens. Enterococcus faecalis was the most prevalent species (11.6%) in positive semen samples and was found to negatively affect both sperm morphology (p = 0.026) and motility (p = 0.003). Analysis of genital swabs from females showed that the presence of E. faecalis (p<0.0001), Escherichia coli (p = 0.0123), Streptococcus agalactiae (p<0.0001), and Gardnerella vaginalis (p = 0.0003) was significantly associated to reduced levels of vaginal lactobacilli. Association of microbiological data with IVF outcome showed that 85.7% of IVF+ couples was microbiologically negative, while IVF was successful in just 7.5% of couples infected with E. faecalis and/or U. urealyticum and/or M. hominis (p = 0.02).

Conclusions: The results show the negative impact of E. faecalis on sperm quality and the association of definite bacterial pathogens with reduced levels of vaginal lactobacilli. The presence of E. faecalis and/or U. urealyticum and/or M. hominis in genital samples of infertile couples is predictive for a negative outcome of IVF.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteria / classification
  • Bacteria / isolation & purification*
  • Enterococcus faecalis / isolation & purification
  • Escherichia coli / isolation & purification
  • Female
  • Fertilization in Vitro
  • Gardnerella vaginalis / isolation & purification
  • Gestational Sac / diagnostic imaging*
  • Humans
  • Male
  • Pregnancy
  • Reproductive Tract Infections / complications
  • Reproductive Tract Infections / epidemiology*
  • Reproductive Tract Infections / microbiology
  • Semen / microbiology*
  • Semen / physiology
  • Sperm Motility
  • Streptococcus agalactiae / isolation & purification
  • Vagina / microbiology*

Grants and funding

The study was supported by the Italian Ministry of Education, University and Research (Ministero dell’Istruzione, dell’Università e della Ricerca; MIUR), ‘Progetti di Rilevante Interesse Nazionale’ (PRIN) 2012 to GP.