Chlamydia primarily affects which type of cell?

Appeared in: AIIMS CRE, SNO-2024

Explanation

Chlamydia trachomatis is an obligate intracellular bacterium, meaning it must live and replicate inside a host cell.
It has a specific affinity, or tropism, for columnar epithelial cells.
These cells are found lining the mucous membranes of the cervix, urethra, rectum, and conjunctiva, which are the primary sites of chlamydial infection.
The infection of these specific cells leads to common clinical presentations like cervicitis and urethritis.

Option A: Chlamydia does not infect red blood cells. These cells lack a nucleus and the necessary cellular machinery for the bacterium to replicate.
Option C: Mature stratified squamous epithelium, which lines the adult vagina and skin, is generally resistant to infection by Chlamydia trachomatis.
Option D: Chlamydia is not a neurotropic organism and does not infect nerve cells.

Visual 1: Diagram - The biphasic life cycle of Chlamydia trachomatis, showing the infectious elementary body entering a columnar epithelial cell and transforming into the replicative reticulate body.
Visual 2: Micrograph - A stained image of cervical cells showing intracellular chlamydial inclusions within the cytoplasm of columnar epithelial cells.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Cellular tropism of Chlamydia trachomatis infection as background academic context rather than a clinical decision trigger.
Understanding that Chlamydia targets columnar epithelial cells explains why diagnostic swabs are taken from the endocervix or urethra, not the outer vagina.
This knowledge is crucial for patient education regarding sites of infection and modes of transmission (genital, anal, oral).
The high rate of asymptomatic infection is partly because the initial infection is contained within the epithelial layer and may not cause systemic symptoms until it ascends to cause Pelvic Inflammatory Disease (PID).

How to Approach the Question

Identify the core of the question: It asks for the specific cell type targeted by the pathogen 'Chlamydia'.
This is a factual recall question based on microbiology and pathology.
Recall or deduce the nature of Chlamydia infection. It is a common sexually transmitted infection (STI) that affects mucous membranes.
Consider the primary sites of chlamydial STIs: the cervix and urethra.
Identify the type of epithelium that lines these areas. The endocervix and urethra are lined predominantly by columnar epithelial cells.
Evaluate the other options. Red blood cells (malaria), nerve cells (rabies, herpes), and squamous cells (HPV) are targets for other specific pathogens, making them incorrect for Chlamydia.

Concept Tested & Keywords

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