Chlamydia is a bacterial STI.

• Caused by Chlamydia trachomatis, naturally found living only inside human cells. Chlamydia trachomatis is an organism responsible for the most prevalent STD in the USA, and is 1 of the 4 bacterial species in the genus Chlamydia. C trachomatis is a gram negative bacterium. It is ovoid in shape and non-motile. The bacteria are non-spore forming but the elementary bodies act as a spore when released into the host. C trachomatis includes 3 human biovars, including:
  • Serovars Ab, B, Ba, or C, cause trachoma: infection of the eyes, which can lead to blindness
  • Serovars D-K, cause urethritis, PID, ectopic pregnancy, neonatal pneumonia, and neonatal conjunctivitis
  • Serovars L1, L2 and L3, cause lymphogranuloma venereum (LGV)
• Many, but not all, C trachomatis strains have an extrachromosomal plasmid. Chlamydia can exchange DNA between its different strains, thus the evolution of new strains is common
• Can be transmitted by oral, anal, or vaginal sex
• The bacteria can be manifested in the vagina, penis, throat, or anus

• Hx of chlamydial, or other STI's
• New or multiple sex partners
• Inconsistent condom use

• Asymptomatic (50% of women, and 75% of men)
• Vaginal discharge
• Abnormal vaginal bleeding
• Dysuria (pain whilst urinating)
• Fever, nausea, vomiting
• Dyspareunia (pain during sex)
• Eye disease
• Between 50-75% of women who have cervicitis [due to chlamydia] are asymptomatic
• Urethritis in men however, is asymptomatic, causing white discharge, with or without dysuria (pain urinating)

• NAAT, e.g. PCR, performed on swabs sampled from the cervix (women) or urethra (men), or self-collected vaginal swabs, or on voided urine
• NAAT has largely replaced culture, the historical gold standard for chlamydia. However, culture remains useful in selected circumstances, such as testing non-genital specimens

• Prevention, including:
  • Screening:
    • Women<25yo should go for regular yearly testing
    • Women>25yo with new sex partners should be tested
    • All pregnant women should be tested
  • Use condoms
  • Advise partner of status
• Antibiotics, abstaining from sex whilst the infection clears up, including:
  • Azithromycin, 1g PO single dose
  • Erythromycin
  • Doxycycline, 100mg PO TDS for 7 days, noting that during pregnancy we can NOT use doxycycline
• Tx partners, and contact tracing if necessary

• Left untreated, can spread to the upper genital tract causing:
  • Pelvic inflammatory disease (PID) in women. PID can in turn can cause scarring inside the reproductive organs, which can cause chronic pelvic pain, infertility, and ectopic pregnancy
  • Epididymitis in men

• Most commonly reported STI
• Most people with chlamydia do not know they are infected
• Chlamydia conjunctivitis is a common cause of blindness worldwide
• Notifiable disease

• Gonorrhea (another bacterial STI)
• Vaginal discharge