LB-19. Time for a Paradigm Shift:  Testing Men Who Have Sex with Men (MSM) for Urethral Infection with C. trachomatis and N. gonorrhoeae Identifies Less than 60% of Infected Men
Session: Poster Abstract Session: Late Breaker Posters
Saturday, October 22, 2011
Room: Poster Hall B1
  • IDSAposter2011.pdf (49.6 kB)
  • Background: We evaluated the performance of nucleic acid amplification tests (NAATs) in diagnosing  urethral, oropharyngeal (ORO) and rectal (R) infection with  C. trachomatis (CT) and N. gonorrhoeae (GC) in MSM. Opportunistic testing for urethral infection has long been the norm. We now report how poor this approach was in identifying infected men.

    Method: We recruited 1089 MSM attending an STD clinic. We tested first catch urine (FCU), ORO and R swabs by ProbeTec (SDA , Becton Dickinson & Co), APTIMA Combo2 (AC2, Gen-Probe Inc) and cultured swabs for CT and GC. Unique NAAT positives were confirmed by repeat testing with alternate primers.

    Result: Of 664 (61%) symptomatic men 285 (43%) had urethral symptoms (32(11.2%) had CT,  93 (32.6%) had GC). Overall prevalence for CT at any site was 12.4% (135/1089) and 21.2% (231/1089) for GC. Prevalence of R infection was 6.7% CT, and 7.7% GC; of ORO infection it was 0.9% CT and 7.3% GC; and FCU+ was 6.7% CT and 13.2% GC.  Testing FCU only would miss 62 (46%) CT and 87 (38%) GC infections in men positive at other sites. CT culture would have detected only 18 R and 4 ORO infections (AC2 detected 62 and 10). GC culture would have detected 37 ORO and 37 R infections (AC2 detected 79 and 84). Thus CT culture sensitivity was 40% for ORO, 29% for R; sensitivity of GC culture was 47% for ORO, 44% for R.  SDA, while more sensitive than culture, detected  >20% fewer ORO and R infections than AC2 (data not shown).

    Conclusion: When evaluating high risk MSM for STDs, testing only for urethral infections is simply inadequate. Adding testing of ORO and R sites with NAATs identified 40% more CT and GC infected MSM than testing only FCU. The use of NAATs made such an observation possible, as culture is too insensitive (AC2 detected twice as many infections). Routine testing of MSM for CT and GC should be based on the client’s sexual activity, and use NAATs.

    Subject Category: C. Clinical studies of bacterial infections and antibacterials including sexually transmitted diseases and mycobacterial infections (surveys, epidemiology, and clinical trials)

    Julius Schachter, PhD and Jeanne Moncada, MT, Univ of CA, San Francisco, San Francisco, CA


    J. Schachter, GenProbe: Investigator, Research support and research support >5 years ago
    Be4cton Dickinson: Investigator, Research support and research support >5 years ago

    J. Moncada, None

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