Beyond the Guidelines: Clinic-Based Screening for Pharyngeal Chlamydia Trachomatis

Background: Gay, bisexual and other men who have sex with men (MSM) remain at high risk for HIV and other STDs. Strategies for STD control include identification of asymptomatically infected persons. CDC guidelines recommend screening MSM for both N. gonorrhoeae (GC) and C. trachomatis (CT) at urethral and anal sites, but only for GC at pharyngeal sites. In June 2010 Callen-Lorde Community Health Center, a clinic serving the LGBT community, added screening of pharyngeal sites for both GC and CT after validating the Gen-Probe's APTIMA Combo-2 NAAT test.

Objectives: To determine the prevalence and characteristics of CT pharyngeal infections among clinic clients

Methods: Results of CT and GC testing from all anatomic sites obtained between 6/1/2010 and 9/30/2011 were reviewed. Positive CT pharyngeal specimens were evaluated to determine characteristics of infection, including presence of symptoms and concurrent site-specific GC/CT infections.

Results: 110 of 5851 pharyngeal tests performed were positive for CT (1.9%). Prevalence was highest amongst HIV infected clients (2.5%). Of the 110 cases, 82% occurred in men (98% MSM) and 10% in transgender clients. 84% of pharyngeal CT infections were asymptomatic. 54.5%  had a second site positive for CT or GC infection; 12.7% had concurrent GC pharyngeal infection, 38.2% had anal CT and 5% had urethral CT. Presence of pharyngeal symptoms was not influenced by GC co-infection.

Conclusions: Pharyngeal CT infections were generally asymptomatic. Rates were highest in HIV-positive clients. Following current CDC guidelines, less than half of the cases would have been treated as a result of detecting concurrent anal or urethral CT infection. Implementing pharyngeal screening resulted in higher rates of detection and treatment of pharyngeal CT.

Implications for Programs, Policy, and Research: The availability of validated CT NAAT testing of oropharyngeal specimens improves detection of pharyngeal CT and should be explored as an additional screening test for those at risk.