On November 14, Mana Rao, second year fellow, presented at journal club recent article Clinical Infectious Diseases.  The main question of her presentation revolved around how effectively are patients at risk of non-urethral Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) being screened.  The population focus of the study was men who have sex with men (MSM).  In this population, receptive partners should have rectal and pharyngeal screened annually in addition to urethral screening.

A significant public health concern exists given approximately 50% of CT infections being diagnosed in Non-urethral sites in this population.  While single centers or regional public health organizations may have data regarding the frequency of testing may reflect local patterns, this study took at different approach: The authors complied data from the entire US from one laboratory corporation (LABCORP).  Then they looked at repeat testing over time. The study period was 30 months.

Most importantly, they used an index rectal CT/GC  test being sent in a male patient (regardless of result) as the inclusion criteria of the study. This functioned as a proxy marker for the population.  The lab data does not have other demographic data that could be used, but this is the key population in which these tests would be sent.  Overall there were 1.6 million patients included in the study.

A few important findings were discussed:

• 17% of index (rectal) specimens were positive- 8% GC, 6% CT and 3% both
• On the index date, pharyngeal and rectal GC were strongly correlated (37-41%), while urine GC was less correlated with Rectal GC (20-30%)
• In patients with initial positive test (GC or CT), repeat testing rate of urine/rectum was 18-19% in the first 3 months, 11-14% for pharyngeal testing during this time
• After 6 months, repeating testing of all sites except urine dropped to 10-15% in the high risk (initial positive) population
• Negative testing at index test was associated with decreased frequency of repeat testing at all sites

Overall this data, which is robust from a numerical standpoint, gives support for multi-site testing in this population (MSM).  Due to lack of clinical data other than basic demographic s (age/gender/region), it is hard to draw additional conclusions as the population is likely heterogeneous.   Comprehensive sexually transmitted infection care (as part of primary care, public health clinic, specialty care) must include sexual history to help direct multi-site screening in appropriate patients.   Controversy still exist regarding reliability of different  non-FDA approved testing for non-rectal PCR testing and the optimal strategy for management pharyngeal CT in asymptomatic patient s (though CDC guidelines err on the side of treatment to prevent possible transmission) (CDC STI Guidelines)

PUBMED:

Tao G  et al Rectal Infection With Neisseria gonorrhoeae and Chlamydia trachomatis in Men in the United States. Clinical Infectious Diseases 2016 Nov 15;63(10):1325-1331