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Diagnosis and management of chlamydia: a guide for GPs

ELEANOR DRAEGER

SPL Chlamydia is a common sexually- transmitted infection caused by Chlamydia trachomatis bacteria. This article discusses its diagnosis and treatment, and considers the GP’s role in management.

hlamydia is the most common sexually-transmitted infection C(STI) in the UK, with 203,116 new diagnoses in England in 2017, of which 126,828 (62%) were in young people aged 15–24 years.1 Chlamydia is transmitted primarily through penetrative sex and infects the urethra and endocervix. It can also infect the throat and the rectum, and in some cases the conjunctiva. It is very infectious, with a concordance of up to 75% between sexual partners. There are many risk factors for chlamydia infection, including being under the age of 25 years, having a new sexual partner and inconsistent use of condoms. If a woman contracts chlamydia during pregnancy it can be transmitted to the baby at delivery, causing conjunctivitis or pneumonia.

Classification of chlamydia infections There are three species of chlamydia bacteria that can cause disease in humans: • Chlamydia psittaci – the natural host is birds, especially par- rots, but it can be transmitted to humans, causing psittacosis • Chlamydia pneumoniae – causes respiratory disease in humans • Chlamydia trachomatis – several different serovars can cause disease (including STIs) in humans, as detailed in Figure 1.

Symptoms The majority of genital chlamydia infections are asymptomatic, but they can cause significant symptoms. In women, chlamydia can cause vaginal discharge, dysuria, abdominal and pelvic pain, post-coital and intermenstrual bleeding, and deep dys- pareunia. In men, chlamydia can cause dysuria, urethral irrita- tion and urethral discharge. Rectal chlamydia is nearly always asymptomatic, but can be associated with anal discharge and discomfort. If a patient presents with proctitis then a diagnosis of lymphogranuloma venereum (LGV) should be considered.

Complications Although an uncomplicated chlamydia infection that is treated promptly carries very little morbidity, if left untreated it can lead

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Chlamydia trachomatis

Serovars A–C Serovars D–K Serovars L1, L2, L3

Trachoma Chlamydia: Lymphogranuloma venereum • urethritis (LGV) • cervicitis • pelvic inflammatory disease (PID) • neonatal pneumonia

Figure 1. Infections caused by the serovars of Chlamydia trachomatis to multiple complications. In women, it can lead to chronic pel- have an annual chlamydia screen, along with a screen when vic pain, pelvic inflammatory disease (PID), ectopic pregnancy, changing sexual partners. Most local authorities also now offer tubal infertility and sexually acquired reactive arthritis (SARA). online STI testing kits (see Box 1). In men, it can lead to epididymo-orchitis and SARA. The cost of The UK’s National Chlamydia Screening Programme (NCSP) treating one episode of PID has been estimated to be around aims to increase early detection and control the transmission £163, which in London alone, with 7000 cases per year, would of chlamydia infection through opportunistic screening of young equate to more than £1 million a year.2 people (see Box 2).

Diagnosis Differential diagnosis The gold-standard test for chlamydia is a nucleic acid amplifi- The differential diagnosis of conditions whose symptoms may cation test (NAAT). Enzyme immunoassay (EIA) tests are rarely resemble chlamydia is summarised in Table 1. performed now, as they are not as sensitive or specific as NAAT. Asymptomatic men should be offered a first-catch urine test Treatment options and asymptomatic women should be offered a vulvo-vaginal First-line treatment self-swab. If women are symptomatic and having a speculum For uncomplicated urogenital, throat and rectal infection, the examination anyway, then a cervical swab can be done, but recommended first-line treatment is doxycycline 100mg twice vulvo-vaginal self-swabs have been shown to be more sensitive, even in symptomatic women.3 It is important to remember that Most local authorities now offer online STI-testing kits – chlamydia can cause dysuria in both men and women, so that if these are self-swabs and/or urine pots, which are posted to a patient has a midstream specimen of urine (MSU) that shows the patient and then processed at a lab in the normal way. ‘sterile pyuria’ then a chlamydia test should be considered. The results are then normally texted to the patient, with Both rectal and throat swabs can be taken by the patient, information as to where to attend for any treatment that and this can be offered for asymptomatic patients. A recent might be indicated. This means that a patient could come review found that rectal chlamydia in heterosexual women was to your surgery with a text message telling them that they common, in that 68.1% of those who had urogenital chlamydia have chlamydia. also had rectal chlamydia, and this was not associated with reported anal intercourse.4 In 2017, 10% of chlamydia tests in those aged 15–24 Patients with proctitis should have an LGV test performed years were done via an online service.1 There have been at the same time as their chlamydia test. This should be done concerns that those who do online tests will not attend for at proctoscopy, and patients should ideally be seen in a gen- treatment, but a 2015 Cochrane review found that there itourinary medicine (GUM) clinic. In addition, asymptomatic was no difference between home-based and clinic-based HIV-positive men who have sex with men (MSM) who have a specimen collections in the proportion of people who positive chlamydia diagnosis should have a test for LGV, as they completed diagnosis and treatment.5 are more likely to have LGV than those who are HIV negative. Anyone under 25 years old who is sexually active should Box 1. Online sexually-transmitted infection (STI) testing prescriber.co.uk Prescriber January 2019 ❚ 13 ■ PRESCRIBING IN PRACTICE l Chlamydia

the four weeks preceding any symptoms and since the diagno- Symptoms Differential diagnosis sis should be contacted. For all other patients, all sexual part- Dysuria Urinary tract infection, gonorrhoea, ners in the six months prior to diagnosis should be contacted. genital herpes All those contacts should be tested for chlamydia and offered epidemiological treatment and a full STI screen. Vaginal discharge Thrush, bacterial vaginosis, In addition, patients and any sexual partners should Trichomonas vaginalis, gonorrhoea, abstain from any sexual activity until treatment has been com- foreign body, physiological pleted. This means abstaining during the week that they are taking doxycycline, or a week after completing the course of Abdominal pain Constipation, urinary tract infection azithromycin. A test of cure, in which you check if the treatment is work- Pelvic pain Endometriosis, pelvic inflammatory ing by retesting the patient, is not routinely recommended for disease chlamydia but one should be done three weeks after completing treatment in the following situations: Rectal discharge Gonorrhoea, inflammatory bowel disease • In rectal infection if an extended course of azithromycin has been used as treatment8 Conjunctivitis Viral, allergic or gonococcal conjunctivitis • In pregnancy Post-coital or Cervical ectropion, cervical cancer, • When symptoms persist intermenstrual pregnancy • Where poor compliance or LGV is suspected. bleeding Routine retesting should also be done three to six months after Table 1. Differential diagnosis of conditions with symptoms that treatment in patients under the age of 25 years. resemble chlamydia GP’s role in management daily orally for seven days. In patients who are allergic to tetra­ GPs are well placed to screen for chlamydia, treat uncompli- cyclines, use azithromycin 1g orally as a single dose, then cated infections and undertake basic partner notification. It 500mg per day for two days. is also important to test for other STIs in the event that the chlamydia test is positive – a basic STI screen consists of Second-line treatment tests for chlamydia, gonorrhoea, HIV and syphilis. While it is The recommended second-line treatment options are: erythro- true that some patients would rather attend a sexual health mycin 500mg twice daily for 10–14 days; or ofloxacin 200mg clinic for any STI-related concerns, there is no reason why they twice daily or 400mg once daily for seven days.7 shouldn’t be able to access their GP for STI screens and treat- ment. Additionally, GPs should consider chlamydia (or other HIV-positive patients STIs) both as a differential diagnosis in patients with related Treatment for urogenital and pharyngeal infection in HIV-positive symptoms and as a screening test in asymptomatic patients, patients remains the same as for HIV-negative patients. Rectal particularly those who are under 25 years. infection should be treated as if it were LGV (unless a nega- If a baby presents with a sticky eye within 30 days of birth, tive LGV result is available) – with three weeks of doxycycline a chlamydia diagnosis should be considered. If the chlamydia 100mg twice daily. The UK’s National Chlamydia Screening Programme (NCSP) Pregnancy was set up in April 2003, and its aims are to: Doxycycline and ofloxacin are contraindicated in pregnancy. • Prevent and control chlamydia through early detection and Recommended treatments are either: azithromycin 1g orally as treatment of asymptomatic infection a single dose, then 500g a day for two days; or erythromycin • Reduce onward transmission to sexual partners 500mg four times daily for seven days; or erythromycin 500mg • Prevent the consequences of untreated infection twice daily for 14 days; or amoxicillin 500mg three-times daily • Raise awareness and skills of health professionals to screen for seven days. for chlamydia, and provide the information young adults need to reduce the risk of infection and transmission.6 Partner notification and test of cure Because chlamydia can be asymptomatic in so many patients, This involves opportunistic screening of young people and because the complications can cause such significant between the ages of 16 and 24 years, with the tests taking morbidity, it is vital that prompt and comprehensive partner place in specialist sexual health services, GP practices and notification is undertaken for all positive diagnoses. This has community settings. It should also include antenatal clinics traditionally been done in GUM clinics but can also be done by (for those under 25 years) and termination services. the GP or practice nurse, with the appropriate training. For male patients with symptoms, all sexual partners within Box 2. National Chlamydia Screening Programme

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test is then positive, it is important to remember that, alongside imens in women and its association with anal intercourse: a systematic the baby, the mother and her partner(s) will also need to be review and meta-analysis. Sex Transm Infect 2018;94(5):320–6. tested and treated. 5. Fajardo-Bernal L, et al. Home-based versus clinic-based specimen col- lection in the management of Chlamydia trachomatis and Neisseria gon- Conclusion orrhoeae infections. Cochrane Database Syst Rev 2015;9:CD011317. Available from: http://dx.doi.org/10.1002/14651858.CD011317. Chlamydia is an infection that is easily missed, but also easily pub2 treated. Due to it being an STI there are additional aspects 6. Public Health England. National Chlamydia Screening Programme to consider with treatment, such as partner notification and standards. 7th edn. October 2016. Available from: https://www.gov. repeat testing to ensure the infection has been eradicated, uk/government/publications/ncsp-standards but all of these things can, and should, be done by GPs where 7. Nwokolo NC, et al. 2015 UK national guideline for the man- appropriate. agement of infection with Chlamydia trachomatis. Int J STD AIDS 2016;27(4):251–67. References 8. BASHH Clinical Effectiveness Group. Update on the treatment of 1. Public Health England. Sexually transmitted infections and Chlamydia trachomatis (CT) infection. September 2018. Available screening for chlamydia in England, 2017. Health Protection Report from: https://www.bashhguidelines.org/media/1191/update-on-the- volume 12, number 20. June 2018. Available from: https://www. treatment-of-chlamydia-trachomatis-infection-final-16-9-18.pdf gov.uk/government/statistics/sexually-transmitted-infections-stis- annual-data-tables Declaration of interests 2. Aghaizu A, et al. What is the cost of pelvic inflammatory disease and None to declare. how much could be prevented by screening for chlamydia trachoma- tis? Cost analysis of the Prevention of Pelvic Infection (POPI) trial. Sex Transm Infect 2011;87(4):312–7. Dr Draeger is currently on a career break from clinical 3. Schoeman SA, et al. Assessment of best single sample for finding medicine and is currently working as a sex education trainer chlamydia in women with and without symptoms: a diagnostic test and freelance medical writer; she previously worked as study. BMJ 2012;345:e8013. a consultant in genitourinary medicine at Lewisham and 4. Chandra NL, et al. Detection of Chlamydia trachomatis in rectal spec- Greenwich NHS Trust

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