Chlamydia Flashcards
What is chlamydia?
Chlamydia trachomatis is a gram-negative bacteria. It is an intracellular organism, meaning it enters and replicates within cells before rupturing the cell and spreading to others. Chlamydia is the most common sexually transmitted infection in the UK and a significant cause of infertility.
What % of chlamydia is asymptomatic?
A large number of cases are asymptomatic (50% in men and 75% in woman). Asymptomatic patients can still pass the infection on.
Briefly describe the National Chlamydia Screening Programme (NCSP)
Public Health England has set out a National Chlamydia Screening Programme (NCSP). This program aims to screen every sexually active person under 25 years of age for chlamydia annually or when they change their sexual partner. Everyone that tests positive should have a re-test three months after treatment. This re-testing is to ensure they have not contracted chlamydia again, rather than to check the treatment has worked.
What STIs are tcommonly tested for at a GUM clinic?
In general, when a patient attends a GUM clinic for STI screening, as a minimum, they are tested for:
- Chlamydia
- Gonorrhoea
- Syphilis (blood test)
- HIV (blood test)
What are the 2 main swab types in sexual health testing?
There are two types of swabs involved in sexual health testing:
- Charcoal swabs
- Nucleic acid amplification test (NAAT) swabs
Briefly describe the use of charcoal swabs
Charcoal swabs allow for microscopy (looking at the sample under the microscope), culture (growing the organism) and sensitivities (testing which antibiotics are effective against the bacteria). Charcoal swabs look like a long cotton bud that goes into a tube with a black transport medium at the end. The transport medium is called Amies transport medium, and contains a chemical solution for keeping microorganisms alive during transport.
Microscopy involves gram staining and examination under a microscope. A stain is used to highlight different types of bacteria with different colours. Charcoal swabs can be used for endocervical swabs and high vaginal swabs (HVS).
What conditions are diagnosed with charcoal swabs?
Charcoal swabs can confirm:
- Bacterial vaginosis
- Candidiasis
- Gonorrhoeae (specifically endocervical swab)
- Trichomonas vaginalis (specifically a swab from the posterior fornix)
- Other bacteria, such as group B streptococcus (GBS)
Briefly describe the use of nucleic acid amplification tests (NAAT) swabs
Nucleic acid amplification tests (NAAT) check directly for the DNA or RNA of the organism. They are not useful for other pelvic infections (except where specifically testing for Mycoplasma genitalium). In women, a NAAT test can be performed on a vulvovaginal swab (a self-taken lower vaginal swab), an endocervical swab or a first-catch urine sample. The order of preference is endocervical, vulvovaginal, and then urine. In men, a NAAT test can be performed on a first-catch urine sample or a urethral swab. It is worth noting that the NAAT swabs will specify on the packet whether the swabs are for endocervical, vulvovaginal or urethral use. A specific kit is used for first-catch urine NATT testing.
Rectal and pharyngeal NAAT swabs can also be taken to diagnose chlamydia in the rectum and throat. Consider these swabs where anal or oral sex has occurred.
Where gonorrhoea is suspected or demonstrated on a NAAT test, an endocervical charcoal swab is required for microscopy, culture and sensitivities.
What conditions are diagnosed with NAAT swabs
NAAT testing is used to test specifically for chlamydia and gonorrhoea.
They are not useful for other pelvic infections (except where specifically testing for Mycoplasma genitalium).
How does chlamydia present in women?
The majority of cases of chlamydia in women are asymptomatic. Consider chlamydia in women that are sexually active and present with:
- Abnormal vaginal discharge
- Pelvic pain
- Abnormal vaginal bleeding (intermenstrual or postcoital)
- Painful sex (dyspareunia)
- Painful urination (dysuria)
It is worth considering rectal chlamydia and lymphogranuloma venereum in patients presenting with anorectal symptoms, such as discomfort, discharge, bleeding and change in bowel habits.
How does chlamydia present in men?
Consider chlamydia in men that are sexually active and present with:
- Urethral discharge or discomfort
- Painful urination (dysuria)
- Epididymo-orchitis
- Reactive arthritis
It is worth considering rectal chlamydia and lymphogranuloma venereum in patients presenting with anorectal symptoms, such as discomfort, discharge, bleeding and change in bowel habits.
How does chlamydia present on examiantion?
- Pelvic or abdominal tenderness
- Cervical motion tenderness (cervical excitation)
- Inflamed cervix (cervicitis)
- Purulent discharge
Briefly describe the diagnosis of chlamydia
Nucleic acid amplification tests (NAAT) are used to diagnose chlamydia. This can involve a:
- Vulvovaginal swab
- Endocervical swab
- First-catch urine sample (in women or men)
- Urethral swab in men
- Rectal swab (after anal sex)
- Pharyngeal swab (after oral sex)
What is the first-line treatment for uncomplicated chlamydia?
First-line for uncomplicated chlamydia infection is doxycycline 100mg twice a day for 7 days.
Why is azithromycin no longer used as a first line treatment for chlamydia?
The guidelines previously recommended a single dose of azithromycin 1g orally as an alternative. This recommendation has been removed due to Mycoplasma genitalium resistance to azithromycin, and azithromycin being less effective for rectal chlamydia infection.
