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Urogenital Chlamydia

Chlamydia trachomatis

For medical students2 min readUpdated 2026-10-10

Urogenital chlamydia is an anthroponotic infection caused by the intracellular bacterium Chlamydia trachomatis. The disease primarily affects the urogenital tract, is frequently asymptomatic, and can lead to severe complications, including infertility.

Pathogen*Chlamydia trachomatis*
Incubation period5 to 30 days
Target in womenCervix
Target in menUrethral epithelium
Risk factorAsymptomatic course in 70–80% of women

Epidemiology and Transmission

Chlamydiae are not part of the normal human microbiota. Their detection always indicates an infectious process, even in the absence of symptoms. The primary source of infection is an infected individual, with women being of particular epidemiological significance due to the frequent asymptomatic course (70–80% of cases).

Modes of transmission:

Pathogenesis and Clinical Presentation

The portal of entry for the infection is the mucous membranes of the genital organs. Initially, C. trachomatis infects the urethral epithelium in men and the cervix in women. The incubation period lasts from 5 to 30 days.

Clinical manifestations are often described as "non-gonococcal urethritis." Symptoms (itching, dysuria, discharge) resemble gonorrhea, but are milder and have a torpid (indolent) course.

If left untreated, the infection spreads upward:

Complications and Reiter's Syndrome

Prolonged chronic inflammation leads to pelvic adhesions, fallopian tube obstruction, and consequently ectopic pregnancy or infertility (including immune infertility due to antisperm antibodies).

A special place among complications is occupied by the autoimmune Reiter's syndrome (urethro-oculo-synovial syndrome). It includes inflammation of the urethra, eye conjunctiva, and joints (primarily lower extremities). The cause lies in molecular mimicry: the heat shock protein (HSP) secreted by chlamydia shares structural similarities with human proteins, prompting the immune system to attack its own tissues.

Diagnosis and Immunity

Post-infection immunity does not develop after chlamydia, and antibodies do not protect against reinfection.

Diagnosis requires a comprehensive approach:

  1. Molecular-genetic methods (PCR, NAATs) and rapid tests (DFA, ELISA for MOMP antigen) are the most modern and accurate.
  2. Culture method is the "gold standard" (cell culture inoculation), but expensive and labor-intensive.
  3. Bacterioscopy – detection of Halberstaedter-Prowazek bodies. Effective for ocular forms, but of low diagnostic value for urogenital infections.
  4. Serology (detection of IgM) is mainly used to diagnose primary infection or neonatal pneumonia.

Principles of Treatment and Prevention

Since C. trachomatis is an intracellular parasite, therapy utilizes antibiotics capable of intracellular accumulation (macrolides, with azithromycin being the drug of choice). Beta-lactam antibiotics are ineffective due to the absence of a conventional peptidoglycan cell wall in chlamydia. Additionally, immunomodulators, local antiseptics, and probiotics are prescribed.

Specific prophylaxis (vaccine) does not exist. The basis for preventing spread is early detection and treatment of infected individuals, and barrier contraception. To prevent fetal infection, pregnant women are prescribed erythromycin (standard prophylaxis for ophthalmia neonatorum does not protect against chlamydia).

Mnemonic

Reiter's triad: "Can't see, can't pee, can't climb a tree" (conjunctivitis, urethritis, arthritis).

Frequently asked questions

What stages does the life cycle of Chlamydia trachomatis include?

The life cycle of Chlamydia trachomatis alternates between two forms (elementary and reticulate bodies) and includes six main stages.

  • Adsorption – attachment of the elementary body to the host cell plasma membrane.
  • Endocytosis (penetration) – invagination of the membrane forming a phagocytic vacuole.
  • Reorganization – transformation of the elementary body into the vegetative form (reticulate body).
  • Multiplication – division of reticulate bodies and formation of inclusions (Prowazek bodies).
  • Maturation – conversion of reticulate bodies back into elementary bodies via intermediate forms.
  • Release – destruction of the infected cell and release of new elementary bodies.
Which serotypes (serovars) of Chlamydia trachomatis cause urogenital chlamydia?

Urogenital chlamydia is caused by "genital" serovars of Chlamydia trachomatis. This group includes 11 serotypes: D, Da, E, F, G, H, I, Ia, J, Ja, and K. These serovars cause non-gonococcal urethritis and can lead to various extragenital complications, including the development of Reiter's syndrome. In newborns, infection with these serovars causes conjunctivitis and pneumonia.

What groups of antibiotics, besides macrolides, are used to treat urogenital chlamydia?

Besides macrolides, tetracyclines and fluoroquinolones are used to treat urogenital chlamydia.

  • Tetracyclines – e.g., doxycycline.
  • Fluoroquinolones – e.g., ofloxacin.

The choice of these groups is due to their ability to cross the host cell membrane and accumulate intracellularly at therapeutic concentrations, which is necessary to eradicate the intracellular parasite. However, in pediatric practice, the use of tetracyclines and fluoroquinolones is strictly limited due to high toxicity.

Why are chlamydiae obligate intracellular parasites?

Chlamydiae are obligate intracellular parasites because they act as "energy parasites." Their own metabolic functions are minimal, and they are incapable of independently synthesizing and accumulating energy (ATP and GTP). To sustain viability, growth, and replication, microorganisms depend entirely on the ATP and metabolites of a living host cell. This is why their replication is possible exclusively inside living cells.

What is Fitz-Hugh-Curtis syndrome, and in which complication of chlamydia does it occur?

Fitz-Hugh-Curtis syndrome is a complication of pelvic inflammatory disease (PID) manifested by perihepatitis. It occurs in disseminated chlamydial infection. Clinically, the syndrome is characterized by pain in the right upper quadrant of the abdomen with normal liver function tests. The pathological process is accompanied by adhesion formation between the liver and the anterior abdominal wall, which appear during laparoscopy like "violin strings." Imaging studies reveal free fluid near the liver.

What complications of urogenital chlamydia develop in men?

In men, urogenital chlamydia can lead to several local and systemic complications.

  • Ascending infection – development of epididymitis, orchitis, and prostatitis.
  • Impaired reproductive function – male infertility (including due to stimulation of antisperm antibody production).
  • Autoimmune processes – development of Reiter's syndrome (urethro-oculo-synovial syndrome), including the triad: urethritis, conjunctivitis, and polyarthritis (reactive arthritis).

Development of inguinal lymphogranuloma and proctitis is also possible.

Can you contract chlamydia in a swimming pool?

Yes, there is so-called "pool chlamydia," in which genital serovars reach the eye mucosa, causing keratoconjunctivitis.

Why do beta-lactams (penicillins) fail to treat chlamydia?

Chlamydiae lack a conventional peptidoglycan cell wall, which is the target for beta-lactam antibiotics.

Does immunity develop after the disease?

No, post-infection immunity does not form, making reinfection possible.

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