Chlamydia spp.
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Chlamydia spp.
Chlamydia is a genus of bacteria that are obligate intracellular parasites. Chlamydia infections are the most common bacterial sexually transmitted infections in humans and are the leading cause of infectious blindness worldwide.
The three Chlamydia species include Chlamydia trachomatis (a human pathogen), Chlamydia suis (affects only swine), and Chlamydia muridarum (affects only mice and hamsters).[2] Prior to 1999, the Chlamydia genus also included the species that are presently in the genus Chlamydophila: Two clinically relevant species, Chlamydophila pneumoniae and Chlamydophila psittaci were moved to the Chlamydophila genus.
| Kingdom | Bacteria |
|---|---|
| Phylum | Chlamydiae |
| Order | Chlamydiales |
| Family | Chlamydiaceae |
| Genus | Chlamydophila |
[edit] Surface Characteristics
The surface consists of specific LPS structures. LPS is composed of three parts: (1) lipid A, (2) core polysaccharide, and (3) O antigen. The lipid A region contains two glucosamine sugar derivatives, each with three fatty acids and phosphate or pyrophosphate attached. The core polysaccharide has KDO and attached to lipid A. The side chain O is small polysaccharide chain extending outward from the core, it has several peculiar sugars and varies in composition between bacterial strains.
[edit] Pathogenic Activity
Most of the times, chlamydial infections do not cause symptoms. Usually, people who engaged in sexual activities with a potentially infected individual may request several tests to diagnose the condition. It is estimated that over 3 million new cases of Chlamydial infections appear every year only in the United States, and overall, 70% of women and 50% of men do not experience symptoms.
Chlamydia can be detected through culture tests, or non-culture tests. The main non-culture tests include Fluorescent Monoclonal Antibody Test, enzyme immunoassay, DNA probes, rapid Chlamydia tests and leukocyte esterase tests. Whereas the first test can detect the major outer membrane protein or the LPS, the second detects a colored product converted by an enzyme linked to an antibody. The rapid Chlamydia tests use antibodies against the LPS, the leukocyte esterase tests detect enzymes produced by leukocytes containing the bacteria in urine.
The non-culture tests may however return a false positive results and are often considered unreliable.
Culture tests are considered 100% reliable. However, results may take up to a week to be obtained and the culture may be easily contaminated.
The most dangerous thing about chlamydia when transmitted sexually is that 75% of women and 50% of men are asymptomatic, and are completely unaware that they are infected. Chlamydia infection is a major cause of infertility, not only in women, but in men as well. Women are subject to pelvic inflammatory disease (PID), and ectopic pregnancy. 40% of women with chlamydia will develop PID and of that 40%, 20% will become infertile and 9% will have a potentially fatal ectopic pregnancy. Recently, research has shown that women infected with chlamydia are 3-5 times more likely to contract HIV. In men, infections often begin in the urethra, with urethritis, and can progress to the upper genital tract, causing epididymitis and prostatitis. In addition it can attach to sperm, which increases the risk of transmission to women. It has been shown that chlamydia can affect sperm health, contributing to male infertility. When infected with chlamydia, sperm show a dramatic decrease in motility, and viability.
Chlamydia has a very unique life-cycle, in which in alternates between a non-replicating, infectious elementary body, and a replicating, non-infectious reticulate body. The elementary body is the dispersal form of the pathogen, and is analogous to the spore. The bacterium induces its own endocytosis upon contact with potential host cells. Once inside a cell the elementary body germinates as the result of interaction with glycogen, and converts to its vegetative, reticulate form. The reticulate form divides every 2-3 hours, and has an incubation period of about 7-21 days in its host. After division, the pathogen reverts back to its elementary form and is released by the cell through exocytosis. They are extremely temperature sensitive, and must be refrigerated at 4 degrees celsius as soon as a sample is obtained.
