EXPERT ANALYSIS FROM THE ANNUAL INTERNAL MEDICINE PROGRAM
ESTES PARK, COLO. (FRONTLINE MEDICAL NEWS) – Close to 80% of men who have sex with men who had gonorrhea or chlamydia in a recent study were infected only at extragenital sites – and therein lies a tale for primary care physicians.
“Five or six years ago my infectious diseases colleagues were pushing extragenital testing in MSM, and I thought then it was a little over the top and excessive. But I now think this is something we should be doing. Two studies from last year highlight this. I think we’re probably missing a lot of infections if we’re only doing genitourinary testing,” John Koeppe, MD, said at a conference on internal medicine sponsored by the University of Colorado.
The testing is quite simple. The same type of swab employed in sampling the urethra or vagina is used to sample the pharynx and rectum and then sent to the laboratory for analysis by nucleic acid amplification test (NAAT). But it’s important to understand that many laboratories are certified to do NAAT only on urethral and vaginal samples.
“It takes labs quite a while to get certified for extragenital testing. Many of my colleagues were sending samples to noncertified labs as urethral samples even though they were actually from the rectum or pharynx. The results were probably reliable. I’ll let you decide if that’s ok,” said Dr. Koeppe, an internist and infectious diseases specialist at the university.
He highlighted one recent potentially practice-changing study in which University of Pittsburgh investigators tested 224 MSM and 175 women with a history of receptive anal intercourse for genitourinary, rectal, and oral gonorrhea and chlamydia. A total of 22.8% of men and 3.4% of women had gonorrhea, while 21.9% of men and 12.6% of women had chlamydia. The major finding: 79.6% of the chlamydia infections and 76.5% of the gonorrhea infections in men were detected by NAAT only in the pharynx or rectum. So were 18.2% of chlamydia and 16.7% of gonorrhea infections in women ( Sex Transm Dis. 2016 Feb;43:105-9 ).
“So in gay men we’d be potentially missing more than three-quarters of infections by only doing genitourinary testing. And in women, it would be more than 16%,” Dr. Koeppe observed.
Moreover, in a national cross-sectional study of 1,071 MSM and bisexual men known as the One Thousand Strong Panel, the prevalence of gonorrhea and chlamydia in urine testing was 0.5% and 1.4%, respectively, whereas in rectal samples the rates were more than threefold higher at 1.8% for gonorrhea and 4.4% for chlamydia.
“Our finding that insertive CAS [condomless anal sex acts] was associated with rectal GC/CT highlights that providers should screen patients for GC/CT [gonococcus/Chlamydia trachomatis] via a full range of transmission routes, lest GC/CT go undiagnosed” the investigators concluded ( Sex Transm Dis. 2016 Mar;43:165-71) .
Dr. Koeppe noted that major guidelines are in discord regarding chlamydia and gonorrhea screening in men. The U.S. Preventive Services Task Force and American Academy of Family Physicians don’t recommend the practice, while the Centers for Disease Control and Prevention and the Canadian STD guidelines do. The Canadian guidelines even include a series of specific questions to ask men to determine if they are at increased risk. If any of the answers raise a concern, then the guidelines urge testing, since chlamydia and gonorrhea are often asymptomatic.
Dr. Koeppe believes the CDC and the Canadians got it right.
“I think it makes sense to screen men. The CDC’s STD surveillance data indicate the incidence of chlamydia infection in U.S. women is twice as high as in men. That probably has a lot to do with the fact that all of the guidelines recommend screening sexually active women under age 25. I don’t think women are getting most of their chlamydia from other women, they’re probably getting it from men who we’re not screening,” said Dr. Koeppe.
He reported having no financial conflicts regarding his presentation.