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Chlamydia trachomatis - Dr Deac Pimp

Definition

  • A very common bacterial STI caused by Chlamydia trachomatis

 

Risk factors

  • Sex without a condom
  • Age 16-25
  • MSM
  • Multiple partners
  • Chemsex

 

Differential diagnoses

  • Gonorrhoea
  • Bacterial vaginosis
  • Trichomoniasis
  • Mycoplasma
  • Herpes
  • Ureaplasma
  • Adenovirus
  • UTI
  • Candida
  • PID

 

Epidemiology

  • 90 million cases worldwide a year
  • 200,000 diagnosed cases in UK in 2016
  • Makes up 49% of all STI diagnoses
  • In 2016, 62% of diagnoses were in 15-24 age group
  • 2% decline in chlamydia diagnoses in 2016 from 2015
  • 9% decline in chlamydia tests in 2016 from 2015

 

Aetiology

  • Caused by Chlamydia trachomatis
    • Gram negative (pink gram stain)
    • Obligate intracellular
    • Very small – not seen by light microscopy
    • Serovars D-K cause ‘standard’ chlamydial infection, type L causes Lymphogranuloma venereum (LGV):
      • Caused lumps which ulcerate
      • Spread to lymph nodes and cause enlargement
      • Causes proctocolitis with ulcers, scarring, adhesions and fistulae
      • Histologically indistinguishable from IBD
      • Treat with 3 weeks of doxycycline

 

Clinical features

  • Asymptomatic in 50% males, 70-80% females
  • Discharge
    • Clear
    • Not usually offensive or coloured
  • Urethritis
    • Pain
    • Dysuria
  • Cervicitis
    • Bleeding
    • Dyspareunia
  • Proctitis
    • Pain
    • Bleeding
  • Conjunctivitis (unilateral, unless from swimming pools)
  •  

 

Pathophysiology

  • Primary infection site is urethra and rectum in men, urethra and cervix in women
  • Incubation period is 7 days
    • Can reliably test from 2 weeks post exposure
  • Majority are asymptomatic and likely clear spontaneously
    • Mediated by Th1 lymphocytes and gamma interferon
    • Some women may have Th2 response, which may lead to scarring

 

Investigations

  • Test from 2 weeks after exposure
  • First-catch urine (held for <1 hour) 15ml
  • Self-taken vulvo-vaginal swab is best in women
  • Cervical, rectal, urethral, pharyngeal swabs can also be taken
  • NAATS testing (nucleic acid amplification test)
    • High specificity and sensitivity
    • Self-taken swabs are better than via speculum
    • For PCR
  • Screen for other STDs
  • Microscopy showing >5 polymorphonuclear leukocytes without diplococci indicates non-gonococcal urethritis, but not specific to chlamydia

 

Management

  • Doxycycline 100mg BD for 7 days OR
  • Azithromycin 1g STAT
  • Test of cure not necessary, but advised after 4-6 weeks
    • Failure rate is 5%
  • Contact tracing if necessary
    • From previous 6 months
  • Follow up 2-4 weeks after treatment (often telephone)
  • Test of re-infection
    • Rate is 21-29%
  • If pregnant or breastfeeding:
    • Erythromycin 500mg BD for 14 days
    • Azithromycin 1g STAT (unlicensed but safe)
    • Test of cure at 1 month

 

 

Prognosis

  • Complications of untreated or repeated infection:
    • Endometritis
    • Salpingitis
    • PID (acute or chronic)
      • In 10-30% untreated
      • 1 episode PID = 21% infertility rate
      • 2 episodes PID = 75% infertility rate
      • Chlamydia responsible for 60% of PID
    • Reduced fertility from fibrosis
      • Worse with every infection
    • Ectopic pregnancy
      • Chlamydia accounts for 60% ectopic pregnancies
    • Arthritis
      • From immune response/antibodies produced NOT presence of bacteria in joints
    • Epididimo-orchitis
    • Fitz-Hugh Curtis Syndrome
      • Presents as acute cholangitis/cholecystitis
    • Co-infection of oncogenic HPV and chlamydia may increase cervical cancer risk
  • Risks in pregnancy and childbirth
    • Vertical transmission rate is 50%
    • Associated with
      • Miscarriage
      • Preterm birth
      • Preterm prolonged rupture of membranes
      • Low birth weight
    • In infants can cause:
      • Conjunctivitis
      • Pneumonitis
        • Staccato cough
        • Failure to thrive
        • Tachypnoea
        • 4-12 weeks after delivery
        • Develops in 10-20% of babies infected with chlamydia
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