Chlamydia trachomatis: Properties, Disease, Lab Diagnosis

By Acharya Tankeshwar •  Updated: 05/04/22 •  3 min read

Chlamydia trachomatis, an obligate intracellular bacteria, causes significant infection and disease worldwide. It is the most common sexually transmitted bacterial pathogen and a major cause of pelvic inflammatory disease (PID) in the USA.

General Properties

Life Cycle of Chlamydia-trachomatis
Life Cycle of Chlamydia trachomatis
  1. Small group of non-motile cocciod bacteria with gram-negative cell wall
  2. Obligate intracellular bacteria (they were once regarded as viruses)
  3. Occurs in two forms:
    1. Elementary body (EB): Non replicating, infectious particle (that can be transmitted from infected person/site to noninfected person/site). #Infective form
    2. Reticulate body (RB): Intracellular growth or replicative form.
  4. Single genus: Chlamydia which contains species C. trachomatis, C. psittaci, and C. pneumonia (TWAR Strains).

Diseases caused by C. trachomatis

Subtypes Route(s) of Transmission Clinical Syndrome
A, B, Ba, CHand to eye from fomites, fliesEndemic trachoma
L1, L2, L3SexualLymphogranuloma venereum
D-KSexual, hand to eye by autoinoculation of genital secretions; eye to eye from infected secretions; neonatal.Urethritis, cervicitis, pelvic inflammatory disease, epididymitis, infant pneumonia and conjunctivitis

 Eyes infection:

 Sexually transmitted Genital and rectal infections:

 Disease caused by C. psittaci and C. pneumoniae

Route of transmission

a. Direct contact

b. Respiratory route: C. psittaci and C. pneumoniae

Laboratory diagnosis of C. trachomatis infection:

Most diseases caused by Chlamydia are diagnosed on the basis of their clinical manifestations. Laboratory diagnosis of C. trachomatis can be achieved by cytology, culture, direct detection of antigen or nucleic acid, and serologic testing.
Specimen: Scrapings from the eyes or urogenital tract, materials aspirated from epididymis, fallopian tubes, sera, tissue biopsy

  1. Cytologic examination of cell scrapings from the conjunctiva of newborns or persons with ocular trachoma by Giemsa staining. Inclusion bodies in scraped tissues can also be identified by iodine staining of glycogen present in the cytoplasmic vacuoles of infected cells and viewing under a microscope. Staining of C. trachomatis elementary bodies by fluorescent monoclonal antibodies.
  2. Serodiagnosis: Serologic testing has limited value for the diagnosis of urogenital infections in adults because most adults with chlamydial infection have had previous exposure to C. trachomatis and are therefore seropositive.  But negative serology can reliably exclude chlamydial infections. Complement fixation test can be used and antibody titer of 1: 64 is indicative of lymphogranuloma venerum (LGV). Detection of C. trachomatis specific IgM is useful in the diagnosis of neonatal infections.
  3. In situ DNA hybridization with cloned C. trachomatis DNA probes in tissue biopsy specimens.
  4. Cultivation/Culture: It is a highly specific test but has lower sensitivity than amplification tests.  Unfortunately, it is highly expensive, technically complex and has stringent transport requirements in terms of both time and temperature.  Cell lines that have been used to isolate C. trachomatis  in cell culture  are McCoy (cycloheximide treated), Hela, Monkey kidney cells

Acharya Tankeshwar

Hello, thank you for visiting my blog. I am Tankeshwar Acharya. Blogging is my passion. As an asst. professor, I am teaching microbiology and immunology to medical and nursing students at PAHS, Nepal. I have been working as a microbiologist at Patan hospital for more than 10 years.

Keep Reading

2 responses to “Leprosy: Etiology, Pathogenesis, Lab Diagnosis”

  1. mwadini says:

    Trichuris trichiura, Trichomonas vaginalis

  2. DEBRA E RODGERS MD says:

    WHO DISCOVERED THAT INJECTION INTO THE ARMADILLO FOOT PAD COULD REPLICATE AN INFECTION WITH ASSOCIATED NEUROPATHY? WHY EVEN MENTION THE MICE SINCE THEY DONOT DEVELOP A DISEASE STATE WHEN INJECTED.?

We love to get your feedback. Share your queries or comments

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: