Do women treated with ceftriaxone and doxycycline for PID benefit from added metronidazole to broaden anaerobic coverage?

Study strengths and limitations

This well-designed randomized, double-blinded clinical trial was performed by clinical investigators experienced in the clinical diagnosis of PID. The demography of the population and their history of C trachomatis, N gonorrhoeae, plus the concurrent diagnosis of bacterial vaginosis make the diagnosis believable and real world, and these factors contribute to the generalizability of the study results.

However, PID is an imprecise clinical diagnosis (specificity averages 65%) when held to the gold standard of diagnostic laparoscopy to confirm the presence of acute salpingitis. Given the reticence of investigators and clinicians to embark on such an invasive procedure to confirm this diagnosis, endometrial biopsy showing evidence of histologic acute endometritis has been offered as an alternative gold standard. Confirmation of acute endometritis in the trial participants would have enhanced the validity of this study.

This study challenges a long held, but never proven, belief that the combination of doxycycline and metronidazole would be poorly tolerated as a combination antimicrobial regimen. It also further solidifies the role of anaerobic bacteria as major players in the microbial etiology of acute PID. In addition, it appears that treating bacterial vaginosis concurrently may lessen the likelihood of endometrial recolonization with anaerobic bacteria. ●