Men and Women Have Similar Neisseria gonorrhoeae Bacterial Loads: a Comparison of Three Anatomical Sites

Neisseria gonorrhoeae is a common bacterial sexually transmitted infection (STI). Currently, there are limited data on the bacterial load in both men and women and on both genital and extragenital sites. Therefore, we quantified N. gonorrhoeae bacterial loads in a large population of women, heterosexual men, and men who have sex with men (MSM) at three different anatomical sites. N. gonorrhoeae-positive samples (n = 1265) of STI clinic consultations (n = 944) were tested for N. gonorrhoeae with the Roche Cobas 4800 system, and quantification cycle (Cq) values were used as an inversely proportional measure for N. gonorrhoeae bacterial load after interpolation from a standard curve. Bacterial loads were compared between sample materials and sexes using t tests. The following mean N. gonorrhoeae loads were observed: urine, 4.5 +/- 1.0 log(10) CFU/ml; vaginal swabs, 4.3 +/- 1.1 log(10) CFU/ml; anorectal swabs (women), 4.0 +/- 1.2 logic, CFU/ml; anorectal swabs (men), 4.5 +/- 1.3 log(10) CFU/ml; oropharyngeal swabs (women), 2.8 +/- 0.9 log(10) CFU/ml; and oropharyngeal swabs (men), 3.2 +/- 1.0 log(10) CFU/ml. Oropharyngeal swabs had a significantly lower N. gonorrhoeae load (P <0.001) than genital and anorectal samples. Loads did not differ between men and women. This is the first study that determined N. gonorrhoeae load in both women and men at three anatomical sites. The substantial N. gonorrhoeae load at all sample sites suggest that all sites may have transmission potential. However, the oropharyngeal site presents the lowest bacterial load. Men and women have a similar N. gonorrhoeae loads on separate anatomical sites, arguing for similar transmission potential and similar clinical relevance.