Lactobacillus iners (L. iners)

Lactobacillus iners is a Gram-positive, facultative anaerobic bacterium that is a prominent member of the human vaginal microbiota (Petrova et al., 2017). While it is a lactic acid-producing bacterium, it is often characterized as a pathobiont because its dominance is frequently associated with vaginal dysbiosis, such as bacterial vaginosis (BV), and an increased risk of adverse reproductive health outcomes, including preterm birth and susceptibility to sexually transmitted infections (Borgdorff et al., 2014). Unlike other vaginal lactobacilli like L. crispatus, L. iners produces only L-lactic acid and expresses inerolysin, a pore-forming toxin that can form pores in host cell membranes, potentially facilitating the transition to a diseased state (Rampersaud et al., 2011). In clinical practice, L. iners is notable for its relative resistance to metronidazole, the standard treatment for BV, which often leads to its persistence or recurrence of dysbiosis after therapy (Muzny et al., 2019). Research into targeting L. iners or its specific metabolic pathways is ongoing to develop more effective treatments for restoring a healthy vaginal microbiome (Macklaim et al., 2013).

Other names

L. inersCST III dominant species

Antibiotics targeting L. iners typically act by inhibiting cell wall synthesis (e.g., Penicillins), protein synthesis (e.g., Clindamycin), or DNA synthesis, although L. iners exhibits unique metabolic pathways that confer resistance to metronidazole (Muzny et al., 2019).