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Should we consider alternatives to combined cervical and urethral swabs for detection of Chlamydia trachomatis in females?
  1. M Mahto1,
  2. H Mallinson2
  1. 1Genitourinary Medicine Department, Macclesfield District General Hospital, Macclesfield, UK
  2. 2Clinical Microbiology and Health Protection Agency Collaborating Laboratory, University Hospital Aintree, Liverpool, UK
  1. Correspondence to:
 Dr M Mahto
 GUM department, Macclesfield District General Hospital, Victoria Road, Macclesfield SK10 3BL, UK; mrinalini.mahto{at}


Background: The optimum approach for detecting Chlamydia trachomatis (CT) is considered to be combined cervical and urethral testing.

Objective: To assess the contribution of female urethral swabs in CT diagnosis and to examine alternatives.

Method: Urethral and endocervical samples for CT were performed on 757 sexually active female patients, >16 years, attending the genitourinary medicine clinic at Macclesfield District General Hospital from October 2005 to November 2006. Swabs were collected and transported to the laboratory in separate AC2 sample collection tubes and were tested by AC2 assay.

Results: Of the 757 patients tested simultaneously by both endocervical and urethral swab, a total of 90 had CT identified by either method giving a positivity rate of 11.9%. Results for urethral and endocervical swabs were concordant in 77 patients (85.6%). Eighty two infections (91.1%) would have been diagnosed by swabbing the cervix only but an additional 8 (8.9%) were picked up by urethral swab. Urethral symptoms had been mentioned by 1 of these 8 women.

Conclusion: 8.9% infected women were positive only on urethral swab. One of these would have been picked up owing to presenting symptoms, hence reducing the extra yield to 7.8% and leaving only 7 positives on 757 urethral swabs with a detection rate of 1% of all urethral swabs. Considering the low yield and the discomfort of urethral swabbing, an additional urethral swab appears unwarranted on grounds of both cost and patient care. As a small number of cases were detected at the urethra but not the cervix, it may be worthwhile investigating the performance of AC2 when placing an endocervical swab in first catch urine. An effective and simpler approach may be a switch to testing vaginal swabs by AC2.

  • AC2, Aptima Combo 2
  • CT, Chlamydia trachomatis
  • CVS, clinician collected vaginal swab
  • FCU, first catch urine
  • PVS, patient collected vaginal swab

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  • Published Online First 4 July 2007

  • Competing interests: None.

  • This study was presented as a poster at the BASHH conference in Blackpool 2–4th May 2007, poster no 47 and published as an abstract ( Int J STD AIDS2007;(Suppl 1):) .