Background/introduction:  The FTD™ Urethritis Plus (FTDU) nucleic acid amplification test (NAAT) detects seven pathogens associated with urethritis: Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Mycoplasma genitalium, Trichomonas vaginalis (TV), Mycoplasma hominis, Ureaplasma urealyticum and Ureaplasma parvum.  
Aim(s)/objectives:  To perform an initial diagnostic evaluation of FTDU performance for NG and CT, compared to routine clinic NAAT (BD Viper), in prospectively collected samples from symptomatic patients or contacts of someone with CT/NG/TV/Non-Specific Urethritis;.
Methods:  Alongside routine clinical samples, additional samples (n=632) were taken from: females (vulvovaginal swabs; VVS), men-who-have-sex-with-women (MSW) (urine) and men-who-have-sex-with-men (MSM) (rectal and pharyngeal swabs; urine). FTDU results were compared with routine clinic NAAT results.
Results:
	CT	NG
Sample type (n)	Females (303)	MSW (103)	MSM Urine
(68)	MSM Rectal
(76)	MSM Pharynx
(82)	Females
(303)	MSW
(103)	MSM Urine
(68)	MSM Rectal
(76)	MSM Pharynx
(82)
Clinic NAAT Positivity (%) 	8.1	19.4	5.3	6.8	3.9	1.5	6.3	20.0	27.4
	23.7
Sensitivity % (95% CIa)	100 (85.8-100b)	100 (83.9-100b)	66.7 (9.4-99.2)	60.0 (14.7-94.7)	50.0 (1.3-98.7)	80.0 (28.4-99.5)	83.3 (35.9-99.6)	50.0 (18.7-81.3)	78.9 (54.4-93.9)	64.7 (38.3-85.8)
Specificity % (95% CIa)	99.6 (97.9-100)	97.4 (90.9-99.7)	98.1 (89.9-100)	96.8 (88.8-99.6)	100 (94.8-100b)	99.6 (98.0-100)	100 (96.1-100b)	100 (92.3-100b)	83.3 (69.8-92.5)	96.4 (87.5-99.6)
Positive Predictive Value  (PPV) (97.5% CIa)	96.0 (79.6-99.9)	91.3 (72.0-98.9)	66.7 (9.4-99.2)	60.0 (14.7-94.7	100
(2.5-100b)	80 (28.4-99.5)	100 (47.8-100b)	100 (47.8-100b)	65.2 (42.7-83.6)	84.6 (54.6-98.1)
Negative Predictive Value (NPV) (95% CIa)	100(98.6-100b)	100 (95.2-100b)	98.1 (89.9-100)	96.8 (88.8-99.6)	98.6 (92.3-100)	99.6 (98.0-100)	98.9 (94.2-100)	90.2 (78.6-96.7)	90.9 (78.3-97.5)	89.8 (79.2-96.2)
a Binomial Exact bone sided, 97.5% Confidence Interval
Discussion/conclusion: FTDU was accurate for detecting CT from genital sites, fulfilling the British Association for Sexual Health and HIV (BASHH) guidelines of a PPV >90% for a NAAT to be selected.   However, it had poor sensitivity for NG at all sampling sites, and with PPVs <90%, supplementary testing would be required to confirm diagnosis.  Further work is required to establish FTDU’s suitability for detecting the other organisms claimed.

Comparison of the FTD™ Urethritis Plus (7-Plex) detection kit with routine sexual health clinic nucleic acid amplification testing for detection of <i>Neisseria gonorrhoeae</i> and <i>Chlamydia trachomatis</i> in urine, vaginal, pharyngeal and rectal samp

Comparison of the FTD™ Urethritis Plus (7-Plex) detection kit with routine sexual health clinic nucleic acid amplification testing for detection of Neisseria gonorrhoeae and Chlamydia trachomatis in urine, vaginal, pharyngeal and rectal samp