Testing for GC and Chlamydia with a self-swab

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Testing for GC and Chlamydia with a self-swab

Dr Robin Clouston PGY3 , FMEM, Dalhousie University

Reviewed by Dr David Lewis

 

Chlamydia is one of the most common sexually transmitted infections we see in the ED and prevalence is highest in ages 15 to 24. The chlamydia incidence rate among youth and young adults in NB increased by 57% between 2007 and 2011, going from 960 to 1,510 per 100,000 persons aged 15 to 24. In Zone 2 of New Brunswick, which includes Saint John, 24% of the population is aged 15 to 24 (data form 2012).1 Three in four cases of chlamydia are seen in this age group and 73% of cases of chlamydia are seen in women. Many cases are asymptomatic and remain undiagnosed. Symptomatic cases may present with cervicitis or urethritis.

In women, signs and symptoms of cervicitis may include mucopurulent endocervical discharge and easily induced endocervical bleeding. Both women and men may present with urethritis, including pyuria, dysuria and increased urinary frequency. In women, the risk of a missed diagnosis of chlamydia is progression to pelvic inflammatory disease, ie spread from the lower reproductive tract (vagina and cervix) to the upper reproductive tract (ie uterus, fallopian tubes, ovaries).2

In the past, testing for chlamydia in women was invasive and required an endocervical sample, necessitating a speculum exam. However, the CDC (Centre for Disease Control) now recommends that vaginal swabs are as sensitive and specific as endocervical swabs for both gonorrhoea and chlamydia.2 A vaginal swab may be self collected with instruction from the clinician. In a large multi-centre trial, women found this testing strategy highly acceptable.3

At SJRHEM we use the Cobas® PCR female swab sample packet, which is suitable for vaginal sampling via clinician-instructed patient self-collection and handling.4 This swab tests for both chlamydia and gonorrhoea. According to CDC guidelines, any patient in whom you suspect chlamydia should also be tested for GC.2

 

 

swab

Instructions for self collection using the Cobas® PCR female swab sample packet:

cobas

 

 

In both men and women presenting with symptoms of urethritis, a urine sample may be used for GC/chlamydial diagnosis. This should be a first-catch urine with no urination in the previous hour. Women who are menstruating cannot use this testing method.4

If a women presents with mucopurulent vaginal discharge as well as abdominal pain, fever or dyspareunia, consider pelvic inflammatory disease rather than a lower-tract chlamydial infection. In this case, a bimanual exam should be performed to test for cervical motion tenderness (CMT), uterine tenderness and adnexal tenderness and masses.5 A vaginal PCR swab may be collected by the clinician at the time of bimanual exam.

Key Message:

Non-invasive self-collection of specimens for chlamydia and gonorrhea can improve diagnosis and increase patient and provider satisfaction. The available evidence suggests that a self-swab is as sensitive as more invasive methods and adopting this strategy is likely to increase the number of test performed in a busy department. So the next time you have a female patient presenting with signs and symptoms of a lower tract chlamydial infection, consider patient self-collection.

 

References:

  1. Office of the Chief Medical Officer of Health (July 2013). New Brunswick Health Indicators. Retrieved June 29 2015, from http://www2.gnb.ca/content/dam/gnb/Departments/h-s/pdf/en/Publications/Health%20Indicators%208_Youth%20sexual%20health_July2013.pdf
  2. CDC 2015 Sexually Transmitted Disease Treatment Guidelines: Chlamydial Infections in Adolescents and Adults. Retrieved July 13 2015 from http://www.cdc.gov/std/tg2015/chlamydia.htm.
  3. Schachter J, Chernesky MA, Willis DE, et al. Vaginal swabs are the specimens of choice when screening for Chlamydia trachomatis and Neisseria gonorrhoeae:  results from a multicenter evaluation of the APTIMA assays for both infections. Sex Transm Dis 2005;32:725–8.
  4. Cobas PCR Sample Kits: The first step to an accurate CT/NG result. Retrieved July 13 2015 from: http://www.roche-diagnostics.ch/content/dam/corporate/roche-dia_ch/documents/broschueren/molecular_diagnostics/hpv_microbiology/PCR_SampleKitBroch_A4_FINAL.pdf
  5. CDC 2015 Sexually Transmitted Disease Treatment Guidelines: Pelvic Inflammatory Disease. Retrieved July 13 2015 from: http://www.cdc.gov/std/tg2015/pid.htm

 

 

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