Chlamydial Genitourinary Infections
- Author: Kelley Struble, DO; Chief Editor: Burke A Cunha, MD more...
Background
Chlamydiae are small gram-negative obligate intracellular microorganisms that preferentially infect squamocolumnar epithelial cells.
Chlamydia trachomatis is one of the 4 species (also including Chlamydia puerorum, Chlamydia psittaci, and Chlamydia pneumoniae) in the genus Chlamydia. C trachomatis can be differentiated into 18 serovars (serologically variant strains) based on monoclonal antibody–based typing assays. Serovars A, B, Ba, and C are associated with trachoma (a serious eye disease that can lead to blindness), serovars D-K are associated with genital tract infections, and L1-L3 are associated with lymphogranuloma venereum (LGV).
Pathophysiology
The pathophysiologic mechanisms of chlamydiae are poorly understood at best. The initial response to infected epithelial cells is a neutrophilic infiltration followed by lymphocytes, macrophages, plasma cells, and eosinophilic invasion. The release of cytokines and interferons by the infected epithelial cell initializes this inflammatory cascade.
Infection with chlamydial organisms invokes a humoral cell response, resulting in secretory immunoglobulin A (IgA) and circulatory immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies and a cellular immune response. Recent studies have implicated a 40-kd major outer membrane protein (MOMP), as well as 10- and 60-kd chlamydial heat-shock proteins (cHSP), in the immunopathologic response, but further studies are needed to better understand these cell-mediated immune responses.[1]
Chlamydiae have a unique biphasic life cycle that is adaptable to both intracellular and extracellular environments. In the extracellular milieu, the so-called elementary body (EB) is found. EBs are metabolically inactive infectious particles; functionally, they are spore-type structures. Once inside a susceptible host cell, the EB prevents phagosome-lysozyme fusion and then undergoes reorganization to form a reticulate body (RB).
The RB synthesizes its own DNA, RNA, and proteins but requires energy in the form of adenosine triphosphate (ATP) from the host cell. After a sufficient amount of RBs have formed, some transform back into EBs, exiting the cell to infect others.
Epidemiology
Frequency
United States
Chlamydia is the most commonly reported infectious disease in the United States; 1.1 million infections were reported in 2007, with the highest prevalence among sexually active females aged 15-24 years.[2]
International
In recent reports, the World Health Organization (WHO) estimated 140 million cases of C trachomatis infection worldwide.[3]
Mortality/Morbidity
Although urogenital carriage of chlamydiae often is asymptomatic, the most common manifestation of disease is local mucosal inflammation associated with a discharge, urethritis in the male, and urethritis/vaginitis/cervicitis in the female.
- Chlamydia is one of the leading causes of pelvic inflammatory disease (PID) and infertility in women. The risk of ectopic pregnancy in women who have had PID is 7-10 times greater than that for women without a history of PID. In 15% of women who have contracted PID, chronic abdominal pain is a long-term manifestation that most likely is related to pelvic adhesions in the ovaries and fallopian tubes.
- Chlamydial infections increase the risk for acquiring HIV infection by increasing genital mucosal inflammation.
- Pregnant women infected with chlamydia can pass the infection on to their infants during delivery, which may develop into chlamydial pneumonia or chlamydial conjunctivitis.
Race
The incidence of chlamydial infection is not related to race per se but rather to the sexual histories of the individuals and, particularly, to the frequency and use (or nonuse) of barrier protection.
Sex
Although the presence of asymptomatic infection with genitourinary chlamydiae can differ, acquisition is similar for both sexes.
Age
Age factors in chlamydial genitourinary infection relate to the age of first sexual exposure and the frequency of exposure.
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