Chlamydia trachomatis is the most prevalent sexually transmitted bacterial infection in the UK, with more than 200,000 cases diagnosed in 2008.1 However, many thousands of cases remain undiagnosed. Population-based studies such as NATSAL (National Survey of Sexual Attitudes and Lifestyles) and the Chlamydia Screening Study (ClaSS) indicate a prevalence of 2%–6% in people aged under 25 years.2,3 Opportunistic testing programs such as the pilot studies in Portsmouth and the Wirral, and the Healthy Respect project in Scotland suggest that as many as 1 in 10 people aged under 25 years may be infected.4–6 In light of the high prevalence of chlamydia, sexually active people who are under the age of 25 years are offered testing either through a screening program (as in England) or opportunistically (as in Scotland).
However, further exploration of the epidemiology reveals that such an approach is not targeted efficiently at those at highest risk of infection. Unsurprisingly the highest prevalence (60%–75%) is found in the sexual partners of people diagnosed with chlamydia, and testing of partners is advocated by the British Association for Sexual Health and HIV guideline.7 Individuals who have previously been diagnosed with chlamydia have the second highest prevalence.8 A systematic review found re-infection rates of 21–30 per hundred person-years in follow up of women aged 16–24 years who attended general practice, family planning, and genitourinary medicine (GUM) clinics in the UK.9 The reasons for this high prevalence include failure to treat past and present partners as well as new ones. As such, the main recommendations of the updated SIGN guideline on C. trachomatis relate to improved management of cases, with a view to reducing re-infection.8
Testing for chlamydia
There are a number of obvious symptoms that should prompt testing for chlamydia, such as urethral discharge and/or dysuria in men. Although the SIGN guideline highlights vaginal discharge in women as a symptom that should prompt testing for chlamydia,8 candidiasis and bacterial vaginosis are much more likely causes, particularly when there has been no recent change in sexual partner.10 Unexpected bleeding, either postcoital and/or intermenstrual, is a more important symptom that indicates the need for testing. Similarly, if during a speculum examination the cervix appears friable and/or bleeds on probing, a chlamydia swab should be taken.8 Chlamydial salpingitis can cause abdominal pain that is relatively mild and intermittent; testing is therefore important in any sexually active woman with lower abdominal pain.8
There is much discussion about which diagnostic specimens should be taken from women. Previously, the two choices were clinician-obtained cervical swabs or first void urine (FVU). However, many studies have now shown that vaginal swabs taken by a clinician are as accurate as cervical swabs, and that self-obtained vulvo-vaginal swabs give results that are as accurate as swabs taken by a clinician. Therefore in women undergoing a speculum examination, either a cervical or vaginal swab can be sent. In women not undergoing speculum examination, either a self-obtained swab or FVU sample can be submitted.8
All healthcare services struggle to test young men for chlamydia, largely because of the lack of opportunistic testing alongside contraceptive advice to young women. However, there is some evidence that postal testing kits may be useful in improving testing rates (see below).8
Identifying groups for screening
The original SIGN guideline on the management of chlamydia11 and the National Chlamydia Screening Programme in England (www.chlamydiascreening.nhs.uk) advocate testing in men and women aged under 25 years without any attempt to prioritise within that large number of individuals. In men, prevalence is similar between the age groups of 15–19 years and 20–24 years.12 In contrast, a systematic review of chlamydia prevalence in women across the UK shows that rates are highest among those aged under 20 years, compared with women aged 20–24 years (see Table 1).12
Therefore, the SIGN guideline recommends that chlamydia testing in women aged 15–19 years be given priority over women aged 20–24 years.8 In all age groups, testing is particularly advised for those who have had two or more sexual partners in the previous 12 months. Testing should also be offered to sexual partners of patients with confirmed or suspected but undiagnosed chlamydial infection (pelvic inflammatory disease or epididymo-orchitis).8
Table 1: Comparison of chlamydia prevalence in different settings in
women below the age of 20 years and those aged 20–24 years old12
|Estimated prevalence of chlamydia (%)|
(95% CI 13.6 to 21.8)
(95% CI 8.9 to 14.9)
(95% CI 6.4 to 23.2)
(95% CI 4.2 to 15.7)
|Termination of pregnancy clinic||12.3
(95% CI 9.8 to 15.3)
(95% CI 6.4 to 10.1)
(95% CI 8.3 to 13.8)
(95% CI 5.1 to 9.6)
|Family planning clinic||10.0
(95% CI 8.7 to 11.5)
(95% CI 5.5 to 7.8)
(95% CI 6.5 to 9.9)
(95% CI 4.3 to 6.3)
|GUM=genitourinary medicine; CI=confidence interval|
An essential component of managing a case of chlamydial infection is partner notification, also referred to as contact tracing. In GUM clinics, this process is traditionally carried out by sexual health advisers, although increasingly all members of the multidisciplinary team can undertake straightforward partner notification. The SIGN guideline recommends that patients diagnosed with chlamydia must receive a partner notification interview. The name, age or date of birth, address, and (mobile) telephone number of recent sexual partners are documented, and agreement is reached as to how these partners are to be contacted. There are three choices:8
- Patient referral: where the index case advises partners to attend
- Provider referral: where a healthcare provider advises partners anonymously to attend
- Conditional referral: where the healthcare provider advises partners to attend if the index case has not done so after an agreed period of time.
If a male index case is symptomatic, all partners in the 4 weeks prior to symptoms should be contacted. In women and asymptomatic men, all sexual partners from the previous 6 months (or the last sexual partner if >6 months ago) should be contacted.8 A follow-up interview at 2–4 weeks (usually by telephone) is carried out to ensure treatment was completed without event, partners have been contacted, and that there was no resumption of sex with an untreated partner.
In settings outside a GUM clinic, a lack of staff dedicated to the task of partner notification often means that this is done poorly or not at all. In primary care there is some evidence that practice nurses trained and supported by GUM health advisers can undertake adequate partner notification,13 but in the absence of specific funding this may prove difficult to implement. In some areas, positive cases of chlamydia are routinely referred to GUM health advisers regardless of where the test was performed, and they are then responsible for follow up and partner notification. This clearly requires agreement with the patient at the time of testing.
Testing for other sexually transmitted infections
The need to test for other sexually transmitted infections (STIs) is controversial, either in patients who ask for chlamydia testing or in those found to be chlamydia-positive. In some parts of the UK, such as most of Scotland, heterosexual patients whose partners do not include intravenous drug users, bisexual men, or people who have had unprotected sex with partners from high-risk geographical areas abroad, are unlikely to be infected with gonorrhoea, syphilis, or human immunodeficiency virus. This does not apply to men who have sex with men or in heterosexual populations in many inner cities in England.8 General practitioners are recommended to take advice from their local GUM clinic or laboratory regarding prevalence of other STIs in their local population. Some laboratories already use combined chlamydia and gonorrhoea tests on a single sample, and the availability of these dual tests is likely to increase. Heterosexual people whose partners include intravenous drug users, bisexual men, or people who have had unprotected sex in high-risk geographical areas abroad should be offered tests for other STIs.
Treatment of chlamydia
Both the 2000 and the updated 2009 version of the SIGN guideline on the management of C. trachomatis recommend azithromycin as first-line treatment on the grounds that single-dose administration, often observed directly, removed concerns over non-adherence.8,11 However, the 2000 SIGN guideline recommended treatment with erythromycin or amoxicillin for pregnant women. Given the high rate of gastrointestinal side-effects with erythromycin and questions about the efficacy of a penicillin in treating chlamydia, this recommendation was deemed unsatisfactory. With growing usage and no evidence of teratogenicity, the advantage of single-dose administration makes azithromycin a preferred option in pregnancy as recommended in the updated guideline.8
General practitioners may be consulted by patients whose partners have been treated for chlamydia at a GUM or sexual health clinic. Delay in treating partners is a significant factor in re-infection, so it is recommended that partners be treated at first consultation without waiting for laboratory confirmation.8 A test should still be undertaken, as a positive result serves as a driver to further partner notification. Patients diagnosed with chlamydia, and their partners should be advised to abstain from sex for at least 7 days after both have completed treatment.
The high rates of re-infection following a diagnosis of chlamydia led SIGN to recommend a repeat test 3–12 months later, or sooner if there is a new partner.8 This is likely to be a challenge, as many patients will not be in contact with services during that time. This role might well fall to GUM health advisers, possibly sending reminders by text to mobile phones. Services that have access to postal testing kits might use these to facilitate re-testing.
Implementation of the guideline
Current trends in testing for chlamydia do not reflect the prevalence of infection. For example in Scotland in 2007, 90,000 tests were carried out in women aged 25–49 years, with a positivity rate of only 4%. In men aged 15–24 years, the positivity rate was 18%, but only 22,000 tests were performed in this group.14 As many tests are carried out in primary care, GPs have an important role in reducing unnecessary testing in the older age groups. This is not always easy as many tests are requested by patients who believe they have been at risk. However, at the very least there is no indication to include routine chlamydia tests for women aged over 25 years during other consultations (e.g. at the time of taking a cervical cytology smear or when providing contraceptive advice).
Reducing the re-infection rate in patients diagnosed with chlamydia will require more intensive follow up and this will undoubtedly be a challenge for primary care. Closer links with specialist sexual health services will be required, either through shared protocols or transfer of responsibility for ongoing management.
A high level of testing in older age groups is wasteful of scarce resources that should be redirected towards those who are most likely to be infected. Better management of the resulting positive cases should lead to fewer re-infections and ultimately contribute to a reduction in chlamydia prevalence. Primary prevention remains crucial, and GPs have an important role in emphasising the benefits of delaying sexual debut, reducing the number of sexual partners, and using condoms routinely.
Current testing strategies are failing to maximise the number of diagnosed cases of chlamydia. Efforts should be concentrated on those most likely to be infected: partners of those diagnosed with chlamydia and those who have been infected before.
Management of individual cases should be improved by undertaking better partner notification and follow-up. This will require closer liaison between general practitioners and GUM clinics.
- The SIGN guideline recommends the use of more targeted screening to detect and treat chlamydial infection
- Effective contact tracing identifies recent sexual partners of index cases who are at the highest risk
- PBC commissioners should discuss with their local public health department local performance against chlamydia screening targets (a national priority)
- Effective contact tracing and follow up could be agreed locally and commissioned from primary and community care services as well as dedicated GUM clinics
- Self testing, postal methods, and community pharmacy led schemes may help reach young males
- Tariff price: GUM outpatient = £139 (new), £86 (follow up)a
- Health Protection Agency. Health protection report 2009; 3 (29). Available at: www.hpa.org.uk/hpr/archives/2009/news2909.htm
- Fenton K, Korovessis C, Johnson A et al. Sexual behaviour in Britain: reported sexually transmitted infections and prevalent Chlamydia trachomatis infection. Lancet 2001; 358 (9296): 1851–1854.
- Low N, McCarthy A, Macleod J et al. Epidemiological, social, diagnostic and economic evaluation of population screening for genital chlamydial infection. Health Technology Assess 2007; 11 (8): iii–iv, ix–xii, 1–165. Available at: www.ncchta.org/fullmono/mon1108.pdf
- Pimenta J, Catchpole M, Rogers P et al. Opportunistic screening for genital chlamydial infection. I: acceptability of urine testing in primary and secondary healthcare settings. Sex Transm Infect 2003; 79 (1): 16–21.
- Pimenta J, Catchpole M, Rogers P et al. Opportunistic screening for genital chlamydial infection. II: prevalence among healthcare attenders, outcome, and evaluation of positive cases. Sex Transm Infect 2003; 79 (1): 22–27.
- Williamson L, Scott G, Carrick-Anderson K et al. Chlamydia trachomatis testing among 13–25 year-olds in non-genitourinary medicine settings. J Fam Plann Reprod Health Care 2007; 33 (3): 177–182.
- British Association for Sexual Health and HIV. 2006 UK National Guideline for the management of genital tract infection with Chlamydia trachomatis. BASHH, 2006.
- Scottish Intercollegiate Guidelines Network. Management of genital Chlamydia trachomatis infection. SIGN 109. Edinburgh: SIGN, 2009. Available at: www.sign.ac.uk/guidelines/fulltext/109/index.html
- Lamontagne D, Baster K, Emmett L et al; Chlamydia Recall Study Advisory Group. Incidence and reinfection rates of genital chlamydial infection among women aged 16–24 attending general practice, family planning and genitourinary medicine clinics in England: a prospective cohort study by the Chlamydia Recall Study Advisory Group. Sex Transm Infect 2007; 83 (4): 292–303.
- Spence D, Melville C. Vaginal discharge. BMJ 2007; 335 (7630): 1147–1151.
- Scottish Intercollegiate Guidelines Network. Management of genital Chlamydia trachomatis infection. SIGN 42. Edinburgh: SIGN, 2000.
- Adams E, Charlett A, Edmunds W, Hughes G. Chlamydia trachomatis in the United Kingdom: a systematic review and analysis of prevalence studies. Sex Transm Infect 2004; 80 (5): 354–362.
- Low N, McCarthy A, Roberts T et al. Partner notification of chlamydia infection in primary care: randomised controlled trial and analysis of resource use. BMJ 2006; 332 (7532): 14–19.
- Sexually Transmitted Infection Epidemiology Advisory Group. Scotland’s sexual health information. Chapter 2: sexually transmitted infections (expanded version). Health Protection Scotland, Information Services Division, 2008. Available at: www.documents.hps.scot.nhs.uk/bbvsti/sti/publications/sshi-chpt2-2008-11-25.pdf G