Microbiota unbalance in relation to high-risk human papillomavirus cervical infection

Objectives: To assess vaginal dysfunction using basic vaginal states and the presence of lactobacillary microbiota in patients with human papillomavirus (HPV) infection with no squamous intra-epithelial lesions (SIL), with low-grade squamous intra-epithelial lesions (L-SIL), and with high-grade squamous intra-epithelial lesions (H-SIL) or squamous cell carcinoma compared with a control group (HPV-negative); to establish the prevalence of bacterial vaginosis, candidiasis, and trichomoniasis in the different age groups; and to characterize the species of lactobacilli according to the type of lesion.

Methods: A cross-sectional study was carried out of patients who underwent clinical examination and collection of vaginal fornixes to study basic vaginal states and culture. Species identification of lactobacilli was performed by mass spectrometry. The results were analyzed using the χ² and Fisher's tests; p<0.05 was considered significant. High-risk viral types were determined using a multiplex real-time polymerase chain reaction test.

Results: A total of 741 patients were analyzed and divided into three age groups: Group 1 aged 18-24 years (n=138), Group 2 aged 25-50 years (n=456), and Group 3 aged >50 years (n=147). All groups were further divided into an HPV-negative (control) group and an HPV-positive group without lesions, with L-SIL, or with H-SIL/squamous cell carcinoma. The prevalence of unbalanced basic vaginal states in patients with H-SIL/squamous cell carcinoma was 72.7% (p=0.03) in Group 1, 53.1% (p=0.05) in Group 2, and no cases of unbalance were detected in Group 3. The prevalence of bacterial vaginosis in women with H-SIL/squamous cell carcinoma in Group 1 was 54.5% and in Group 2 was 43.7%. Patients with H-SIL/squamous cell carcinoma had a prevalence of 21.4% of Lactobacillus crispatus, 42.9% of L. jensenii, and 14.3% of L. iners.

Conclusions: A greater unbalance of vaginal microbiota was observed in patients with SIL, especially in those with H-SIL/squamous cell carcinoma. In this group, an increase in L. jensenii and L. iners compared with control was found. L. crispatus had a similar prevalence to the control group. It is important to characterize the lactobacilli species since the unbalance alters the vaginal microenvironment and acts as a co-factor in the persistence of HPV infection.