Abnormal vaginal pH and Mycoplasma genitalium infection.

Study Objective: Mycoplasma genitalium (MG) is a sexually transmitted pathogen linked to female morbidity, but testing for MG is not standardized. We aimed to determine which point-of-care (POC) vaginal tests could predict MG infection.

Design, Setting, Participants: A cross sectional study recruited sexually active adolescent women, aged 14-22 y (n = 217) from an urban medical center.

Interventions And Main Outcome Measures: Vaginal swabs were POC tested for pH, amines, clue cells, sialidase, and Trichomonas vaginalis (TV). MG was detected by research-use-only transcription mediated amplification (TMA) assay. Presence of Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) were confirmed using TMA. Three criteria were required for diagnosis of clinical BV: pH > 4.5, presence of amines, and >20% clue cells. Associations were assessed using logistic regression (LR).

Results: TMA detected MG in 30 (14%), CT in 49 (23%), and NG in 21 (10%) of the samples tested. POC vaginal tests were positive for TV in 21%, amines in 52%, clue cells in 33%, sialidase in 22%, pH > 4.5 in 56%, and clinical BV in 19% of the samples tested. Using LR, pH > 4.5 was a predictor of MG (odds ratio 4.4, P < .05). Of 131 women without clinical BV or TV, 25% of those with pH > 4.5 had MG, compared to 9% of those with pH ≤ 4.5 (P = .02).

Conclusions: Until standardized, approved testing for MG is available, pH may be a useful indicator to suspect MG, especially in the absence of BV and TV.