Objectives As pelvic inflammatory disease (PID) aetiology is not completely understood, we examined the relationship between select novel bacteria, PID and long-term sequelae.

Methods Fastidious bacterial vaginosis (BV)-associated bacteria (Sneathia (Leptotrichia) sanguinegens, Sneathia amnionii, Atopobium vaginae and BV-associated bacteria 1 (BVAB1)), as well as Ureaplasma urealyticum and Ureaplasma parvum were identified in cervical and endometrial specimens using organism-specific PCR assays among 545 women enrolled in the PID Evaluation and Clinical Health study. Risk ratios and 95% CIs were constructed to determine associations between bacteria, histologically confirmed endometritis, recurrent PID and infertility, adjusting for age, race, gonorrhoea and chlamydia. Infertility models were additionally adjusted for baseline infertility.

Results Persistent detection of BV-associated bacteria was common (range 58% for A. vaginae to 82% for BVAB1) and elevated the risk for persistent endometritis (RR_adj 8.5, 95% CI 1.6 to 44.6) 30 days post-cefoxitin/doxycycline treatment, independent of gonorrhoea and chlamydia. In models adjusted for gonorrhoea and chlamydia, endometrial BV-associated bacteria were associated with recurrent PID (RR_adj 4.7, 95% CI 1.7 to 12.8), and women who tested positive in the cervix and/or endometrium were more likely to develop infertility (RR_adj 3.4, 95% CI 1.1 to 10.4). Associations between ureaplasmas and PID sequelae were modest.

Conclusions To our knowledge, this is the first prospective study to demonstrate that S. sanguinegens, S. amnionii, BVAB1 and A. vaginae are associated with PID, failure of the Centers for Disease Control and Prevention-recommended treatment to eliminate short-term endometritis, recurrent PID and infertility. Optimal antibiotic regimens for PID may require coverage of novel BV-associated microbes.