Screening and treatment of Chlamydia trachomatis infections

Chlamydia infection in women

Upper genital tract infection with C trachomatis can cause ectopic pregnancy and tubal factor infertility. A systematic review found estimated incidences of pelvic inflammatory disease of 0-30% in women with untreated infection but insufficient evidence to define the relation.5 A recent review of risk estimates of the complications of chlamydia infection concluded that 10-20% of women with pelvic inflammatory disease will develop tubal infertility and that chlamydia positive women have a 0.1-6% risk of developing tubal infertility.6

Ectopic pregnancy occurs in about one in 1000 conceptions in England (about 8000 cases a year treated in hospital), which is similar to other European countries.1 The relation between ectopic pregnancy and chlamydia infection is uncertain: three large retrospective cohort studies found a decreased risk of ectopic pregnancy in women with previous chlamydia infection,7 no difference,8 and an increased risk.9 The women in these studies had diagnosed infections and were presumably treated, so the findings do not reflect the risk of ectopic pregnancy in women with untreated infections. A study that used population registry data from Amsterdam estimated that women with current genital chlamydia infection had a 0.07% risk of ectopic pregnancy.10

Chlamydia infection in men

Chlamydia can cause epididymitis and epididymo-orchitis, but little is known about the epidemiology of complications in men.2

Infection in pregnancy

Adverse pregnancy outcomes that have been associated with asymptomatic chlamydia infection include premature rupture of membranes, preterm delivery, low birth weight, and neonatal conjunctivitis and pneumonia.^{w6 w7} Debate on management exists: National Institute for Health and Clinical Excellence guidance does not recommend chlamydia screening during pregnancy,11 whereas the US guidance does.2

Other sequelae

In both sexes infection with chlamydia can cause sexually acquired reactive arthritis and proctitis.^w8

An opportunistic screening approach

The English national chlamydia screening programme offers opportunistic screening because most young people in England visit primary care sexual health services and response rates to invitations to screening in this age group are low. Two UK pilot studies conducted in 2001 showed that this approach was feasible in young women, with a high rate of uptake, detection of infection, and treatment in primary care.^w16

Young men and women are offered tests when they visit primary care sexual health services such as community sexual and reproductive health services, general practice, and pharmacies. Repeat testing is recommended annually or after a change of sexual partner (fig 3⇓).

Fig 3 English national chlamydia screening programme flow chart

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Six other European countries offer opportunistic testing—Denmark, Estonia, Iceland, Latvia, Norway, and Sweden—but not as part of a national coordinated programme.1 The US Centers for Disease Control and prevention (CDC) recommends that all sexually active women aged 25 years and younger should be screened for chlamydia.2

Regardless of the approach to screening, primary prevention of infection through delivering information about safer sex practices must underpin any strategy to control chlamydia.

Does testing young men improve the outcome of screening?

Most sequelae of chlamydia infection affect women, and most screening activities worldwide target young women. We have no direct evidence that the burden of disease in women falls when men are screened, and most modelling studies find that screening men is less cost effective than screening women. However, screening men may be a cost effective adjunct to screening women if men at high risk are targeted.19

The English screening programme offers screening to both men and women under the age of 25 to encourage young men to take an active part in maintaining their own sexual health and that of their partners. Young men form a large pool of undiagnosed and untreated infection but are difficult to reach because they visit healthcare facilities less often than young women.^w17 The development of non-invasive tests for men, such as urine based nucleic acid amplification testing, has made screening acceptable.20 Consultation with young men has shown that many prefer testing for chlamydia via routes that prioritise anonymity, such as the internet.^w18

Samples

Nucleic acid amplification testing requires self taken vaginal swabs or urine samples,^w19 and a clinical examination is not needed. Men should provide a first void 15-50 ml sample of urine, and women should provide a similar sample or a self taken vaginal swab.

Tests

A 2002 review of tests from the 1990s onwards found that nucleic acid amplification is more sensitive and specific than enzyme immunoassay.^w20 Technology continues to develop, but currently no enzyme immunoassays, point of care tests, or DNA probe tests are recommended for the diagnosis of C trachomatis because of low sensitivity and specificity.21 Nucleic acid amplification has a high sensitivity (90-97%) and specificity (99%),^w21 and samples are suitable for testing several days after collection, even if kept at room temperature.^w22

Potential effects of chlamydia screening

Possible harms from chlamydia screening are the distress caused by a positive result and anxiety about partner notification.^w23 The positive effects include reassurance when tests are negative and the benefit of early treatment when tests are positive.^w24

Treating the infected person

Chlamydia infection is easily treated. A single dose of azithromycin (1 g orally) is highly effective—more than 95% of those treated are negative for chlamydia after two weeks.22 The single dose option increases compliance. Advise patients to avoid sexual contact during treatment and for seven days afterwards to prevent reinfection before the treatment has been effective. Box 1 gives a more comprehensive list of treatment options.

No test of cure is needed if treatment has been taken correctly and the advice to prevent reinfection has been followed. The exception is pregnant women, who have a reduced cure rate because increased hepatic clearance results in lower plasma concentrations of erythromycin,^w26 and a test six weeks after treatment is recommended. Reinfection is 20-30 per 100 person years23 and the CDC recommends retesting after three to four months, although the English programme does not.2

Treating partners

Two studies have shown that 57-75% of partners of people who test positive for chlamydia are also positive, so people who are diagnosed with chlamydia are at risk of reinfection if their partner is not treated. Treatment of partners is therefore an important part of the management of chlamydia infection.^{w27 w28}

We have no clear evidence to guide how far back in time partners of the index case should be traced and informed. For asymptomatic people, the British Association for Sexual Health and HIV advises six months or the last partner before diagnosis if the interval between last sexual activity and diagnosis is longer than six months. For those with symptoms this period is one month.^w25

Notifying partners

Partner notification is the process of informing sexual partners of people diagnosed with a sexually transmitted infection about their potential exposure to infection. It aims to increase testing and treatment among partners who are at high risk, to prevent reinfection of the index case, and to prevent onward transmission in the community. This is an important part of managing any sexually transmitted infection. The stigma attached to sexually transmitted infections can make partner notification difficult. More partners are likely to be treated if a health professional contacts them (provider referral) than if patients do this themselves (patient referral).24 In practice, however, both patients and doctors prefer patient referral.25 26 Current methods of patient referral reach only 40-60% of named sexual partners.25

New methods of partner management are emerging, and a systematic review of interventions to supplement simple patient referral found that involving index patients in the care of sexual partners improves the outcomes of partner notification for chlamydia, gonorrhoea, and non-specific urethritis. Patient delivered treatment for partners, home sampling, and additional information for partners were more effective than simple patient referral.24 Although patient delivered partner treatment is not licensed in the UK, a variant that includes referring partners to local pharmacies for treatment or giving index patients treatment for their partners after a telephone consultation with the partner are being piloted.^w29

Further screening for other sexually transmitted diseases

Patients who test positive for chlamydia should be offered more comprehensive screening and considered for referral to specialist services.2 Many screening tests can be initiated in primary care such as blood tests for HIV and syphilis. Some primary care services offer dual nucleic acid amplification testing for chlamydia and gonorrhoea on a self taken vaginal swab or urine sample, but routine dual testing is not recommended unless the local prevalence of gonorrhoea is high.27

General practice

Young people find screening in a general practice acceptable and most visit their doctor at least once a year.^w30 With appropriate training, general practices are well placed to screen for and treat chlamydia and to offer partner notification.^w31 In England, general practitioners, practice nurses, and healthcare assistants play an important role in offering chlamydia testing. An offer of screening can easily be made during any consultation and could fit in with a wider discussion about relationships, sexual health, and general lifestyle advice.

A routine offer of screening to all young people stops them feeling that they are being targeted because of their sexual behaviour.28 Young people prefer not to be seen asking for, or being asked to take, chlamydia tests; this may mean that tests should not be initiated by doctors’ receptionists (box 2).29

In England the national chlamydia screening programme has stimulated more discussion of sexual health in general practice, and chlamydia tests in this setting increased from 2341 in 2003-4 to 106 886 in 2008-9.^w5

Pharmacies

UK pharmacies are increasingly important providers of chlamydia screening. About 79% of the UK population lives within 0.6 mile (1 km) of a pharmacy, pharmacies have long opening hours, and they already offer some sexual health services. Chlamydia screening has been shown to be acceptable in this setting,^w33 and some pharmacies offer NHS funded treatment for people under 25 and their partners with chlamydia.

Community sexual reproductive health

Community sexual reproductive health services already reach large numbers of young people for contraception and since the inception of the national chlamydia screening programme have been the major provider of screening tests.^w34 The addition of chlamydia screening to these services is often a first step towards more holistic sexual health care in these settings.^w35