Background: In 2010, the Centers for Disease and Control and Prevention recommended using nucleic acid amplification tests (NAATs) for extragenital gonorrhea (GC) and chlamydia (CT) testing because of NAATs’ improved sensitivity compared with culture.
Methods: In 2011, the Public Health–Seattle & King County Sexually Transmitted Disease Clinic introduced NAAT-based testing for extragenital GC and CT infection in men who have sex with men (MSM) using AptimaCombo2. We compared extragenital GC and CT test positivity and infection detection yields in the last year of culture-based testing (2010) to the first year of NAAT testing (2011).
Results: Test positivity of GC increased by 8% for rectal infections (9.0%–9.7%) and 12% for pharyngeal infections (5.8%–6.5%) from 2010 to 2011; CT test positivity increased 61% for rectal infections (7.4%–11.9%). Pharyngeal CT was identified in 2.3% of tested persons in 2011 (not tested in 2010). We calculated the ratio of extragenital cases per 100 urethral infections to adjust for a possible decline in GC/CT incidence in 2011; the GC rectal and pharyngeal ratios increased 77% and 66%, respectively, and the CT rectal ratio increased 127%. The proportion of infected persons with isolated extragenital infections (i.e., extragenital infections without urethral infection) increased from 43% in 2010 to 57% in 2011.
Conclusions: Extragenital testing with NAAT substantially increases the number of infected MSM identified with GC or CT infection and should continue to be promoted.
Nucleic acid amplification test increases detection of extragenital gonorrhea and chlamydia infections among men who have sex with men at the Public Health–Seattle & King County Sexually Transmitted Disease Clinic.
From the *Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, WA; †Public Health–Seattle & King County HIV/STD Program, Seattle, WA; and ‡Department of Epidemiology, University of Washington, Seattle, WA.
Funding support: This work was supported by Public Health–Seattle & King County, the National Institutes of Health Sexually Transmitted Diseases Training Grant (T32 67-4198 to L.A.B.), the National Institutes of Mental Health (K23MH090923 to J.C.D.), the National Institutes of Allergy and Infectious Diseases (K01 AI095060 to R.P.K.), and the University of Washington Center For AIDS Research, a National Institutes of Health–funded program (P30 AI027757) that is supported by the following National Institutes of Health institutes and centers: National Institutes of Allergy and Infectious Diseases, National Cancer Institute, National Institutes of Mental Health, National Institute on Drug Abuse, National Institute of Child Health and Human Development, National Heart, Lung, and Blood Institute, and National Institute on Aging
Conflicts of interest: L.A.B., J.C.D., and R.P.K. have nothing to disclose. M.R.G. received research support from Genprobe Diagnostics, Cempra Pharmaceuticals, and Pfizer Pharmaceuticals.
Correspondence: Lindley Barbee, MD, MPH, 325 9th Ave, Box 359777, Seattle, WA 98104. E-mail: firstname.lastname@example.org.
Received for publication March 14, 2013, and accepted December 16, 2013.