News
MSM Can Effectively Self-Test for Chlamydia, Gonorrhea
Major Finding: The only time a provider’s test was positive and a patient’s test was negative was a single case of pharyngeal gonorrhea.
QUEBEC CITY – Be sure to screen men who have sex with men for gonorrhea, and don’t ignore the rectum, based on data from 1,076 MSM.
"Rectal gonorrhea probably predisposes individuals to HIV infection," said Dr. Marcus Chen of the University of Melbourne.
Gonorrhea infection of the pharynx and rectum is usually asymptomatic, but data show that these areas can be reservoirs of infection that can be transmitted during oral or anal sex, Dr. Chen said.
Understanding the natural history and transmissibility of the infection may help control the spread of gonorrhea in MSM, but data on the transmissibility of gonorrhea from the pharynx and rectum are limited, said Dr. Chen, who presented the data at the congress of the International Society for Sexually Transmitted Diseases Research.
In this study, Dr. Chen and his colleagues identified the gonococcal bacterial loads at the pharynx and rectum.
The study population included 1,076 consecutive MSM who were tested for gonorrhea at a single health center between January 2010 and April 2010. The mean age of the study population was 32 years.
Rectal and pharyngeal swabs were taken from each patient, and the samples were testing using both culture and polymerase chain reaction (PCR). A total of 1,011 rectal samples and 1,076 pharyngeal samples were analyzed.
Overall, the prevalence of pharyngeal gonorrhea was 4%, the prevalence of rectal gonorrhea was 5%, and the prevalence of gonorrhea in both locations was 1%. There were no symptomatic pharyngeal infections, but the prevalence of symptomatic rectal infections was 16%.
The bacterial loads were significantly higher in rectal infections, compared with pharyngeal (18,960 vs. 2,100 copies per swab), and higher in symptomatic rectal infections, compared with asymptomatic samples (278,800 vs. 13,980 copies per swab), Dr. Chen noted.
The sensitivity of the gonorrhea culture, compared with PCR, was 39% with a specificity of 53%, Dr. Chen noted. Consequently, bacterial loads were significantly higher in the positive cultures, compared with the negative cultures, for both types of gonorrhea.
The study is the first to compare the bacterial loads of gonorrhea in the pharynx and the rectum, Dr. Chen said. "Lower bacterial loads in the pharynx, compared with the rectum, point to possible lower transmission risk," he said. But more research is needed, including prospective studies to quantify the transmission of gonorrhea between MSM partners, he added.
Findings from additional studies could help doctors design more effective ways to screen for and control gonorrhea in the MSM population, Dr. Chen said.
Dr. Chen said that he had no financial conflicts to disclose.