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MRCGP hot topics - chlamydia

Dr Andrew Perry gives an overview of a topic that could come up in either the new or old MRCGP exams

Dr Andrew Perry gives an overview of a topic that could come up in either the new or old MRCGP exams

Chlamydia trachomatisis is a sexually acquired bacterial infection of the genital tract and is one of the most common STIs in the young population. Estimates of incidence vary but in 2005 there were around 110,000 diagnoses made in GUM clinics in the UK. The highest rates of infection are in 16 to 19-year-old females and 20 to 24-year-old males. This rate has continued to increase over the last decade1.

Signs and symptoms

Estimates show that up to 80% of females and 40% of males are asymptomatic when infected with Chlamydia. In females symptoms include:-

• intra-menstrual bleeding / breakthrough bleeding when on oral contraceptive pill

• postcoital bleeding

• vaginal discharge

• lower abdominal pain

• mucopurulent cervicitis

In males the usual presenting symptoms are discharge and/or urethritis.


The most concerning complication of untreated Chlamydia infection is pelvic inflammatory disease with the potential for future infertility. Left untreated, Chlamydia infection causes pelvic inflammatory disease in around 30 to 40% of patients. After one episode of PID tubal fertility has been found to occur in 11% of women. In addition to this the risk of ectopic pregnancy is increased2,3. In men ascending Chlamydia can cause epididymitis, but there is limited evidence of its effects on male fertility.


The incubation period for Chlamydia can be 14 to 21 days and this should be considered in patients who often present quite soon after a particular episode of unprotected sexual intercourse. In males chlamydia can be diagnosed using first pass urine held for at least one hour prior to voiding. Preferably though men should hold urine for around four hours. In females best diagnosis is achieved by an endocervical swab. However urine and self-taken high vaginal swab now offer a reasonable level of detection and are often more acceptable to patients. In all circumstances the samples are analysed using Nucleic Acid Amplification Techniques (NAAT). Often this is using Strand Displacement Assays which in some centres is also now being used to detect Neisseria Gonorrhoea as well.


Azythromycin 1g as a stat dose is indicated in chlamydia infection. While not licensed, it is considered to be safe in pregnancy and lactation. Alternatively doxycycline 100mg bd for seven days may be used; or erythromycin 500mg qds for 14-day in pregnancy. Patients must be advised to abstain from sexual intercourse during and for seven days after completing treatment.


Partner tracing and epidemiological treatment of contacts is a vital part of managing chlamydia. Patients are best referred to GUM departments who have health advisers specifically trained in dealing with these issues in a sensitive and discrete manner. It is standard to offer epidemiological treatment to all contacts of chlamydia prior to testing. Some centres advocate arranging a test of curse [WOT? check] five to six weeks after completion of treatment.

The national Chlamydia screening programme

This was set up as part of The Department of Health's national strategy for sexual health and HIV. Screening programmes began in April 2002 in 10 areas. The scheme now covers the whole of England managed under the Health Protection Agency. Questions still exist about the funding of screening in primary care and where the responsibility lies for treatment and follow-up of cases.

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