Gardnerella bacteria in the cervicovaginal microbiome may serve as a biomarker to identify women infected with human papillomavirus (HPV) who are at risk for progression to precancer, according to a new study.

HPV infection is one of the most common sexually transmitted infections and the causal agent of cervical cancer. But it is still not clear why only a small proportion of high-risk HPV infections progress to cervical cancer. To investigate the potential role of the cervicovaginal microbiome, Burk, Usyk and their collaborators evaluated cervical samples from 273 women who had high-risk HPV infection and were participating in the Costa Rica HPV Vaccine Trial.

They found that the abundance of Lactobacillus iners was associated with clearance of high-risk HPV infections. By contrast, Gardnerella bacteria were the dominant biomarker for progression of a high-risk HPV. Additional analyses revealed that the effect of Gardnerella is mediated by increased cervicovaginal bacterial diversity directly preceding the progression of a persistent infection to precancer. The findings suggest that monitoring the presence of Gardnerella and the subsequent elevation in microbial diversity could be used to identify women with persistent high-risk HPV infection at risk for progression to precancer. If future studies support a causal role of the cervicovaginal microbiome and disease progression, then it might be possible to manipulate the cervicovaginal microbiome in a manner to activate a local immune response and prevent disease progression.

The authors add, «The investigators prospectively demonstrate that progression of a persistent high-risk HPV infection to cervical precancer is in part explained by unique features of the cervicovaginal microbiota.»

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