Chlamydia

A type of bacteria that causes an infection very similar to gonorrhea in the way that it is spread, the symptoms it produces, and the long-term consequences. Like gonorrhea, chlamydia is found in the cervix and urethra and can also live in the throat or rectum. Like gonorrhea, it is highly destructive to the tubes (the fallopian tubes), the conduits through which the eggs voyage from the ovary to the womb. As a consequence, it causes infertility and tubal pregnancies (pregnancies that implant ectopically in the tubes, a potential disaster). Again like gonorrhea, chlamydia is a prime cause of severe pelvic inflammatory disease (PID). Because women newly infected with chlamydia tend not to have symptoms (to be "silent" or symptom-free), chlamydia often goes undetected and untreated, the disease can progress in a stealthy way to wreck extensive destruction of the fallopian tubes and lead to infertility. Once again like gonorrhea, chlamydia is associated with an increased incidence of preterm births (premies). Women with a history of chlamydia have an increased risk of developing cancer of the cervix. The infant can also acquire the disease during his or her passage through the birth canal, leading the baby to have eye disease or pneumonia. This is one of the reasons that all newborns are treated with eye drops after birth. The drops contain an antibiotic which treats chlamydia. Treatment of all newborns is routine because of the large number of infected women without symptoms and the dire consequences of chlamydial conjunctivitis to the newborn. Chlamydia can cause a spectrum of disease in men including urethritis (inflammation of the urethra), epididymitis (inflammation of the epididymis) and proctitis (inflammation of the rectum). About 4 million Americans — most of them teenagers and young adults — contract chlamydia each year. Home tests for chlamydia may help prevent the long-term complications of the infection. The home test for chlamydia has been available since 1996. Before that, the infection was detected only through swab samples taken by doctors. The home test involves mailing a urine sample to a lab, saves time and provides privacy.

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The only genus of the family Chlamydiaceae, including all the agents of the psittacosis-lymphogranuloma-trachoma disease groups; c. are obligatory intracellular spherical or ovoid bacteria with a complex intracellular life cycle; the infective form is the elementary body, which penetrates the host cell, replicating as the rediculate body by binary fission; replication occurs in a vacuole called the inclusion body; c. lack peptidoglycan in their cell walls; the type species is C. trachomitis. Formerly called Betsonia. SYN: Chlamydozoon. [G. chlamys, cloak]

- C. pneumoniae a bacterial species first isolated in 1986 and currently recognized as a common cause of pneumonia, bronchitis, rhinosinusitis, and pharyngitis in both adults and children. SYN: TWAR.C. pneumoniae is responsible for about 25% of cases of acute bronchitis and 10% of community-acquired pneumonia. Recent studies have suggested that it may also play a role in the genesis of cardiovascular disease and late-onset Alzheimer dementia. Like C. trachomatis and C. psittaci, this organism is an occasional cause of myocarditis and endocarditis. Elevated levels of antibody to C. pneumoniae are found in persons with acute myocardial infarction (MI), and in persons showing significant atheroma formation at autopsy, significantly more often than in control groups. The organism has been detected by immunocytochemistry, polymerase chain reaction, and electron microscopy in macrophages and smooth muscle cells of atheromatous plaques of the aorta, coronary arteries, and carotid arteries (surgical and autopsy specimens), but not in normal arteries. The incidence of acute infection in MI patients, as detected by throat culture, is higher than in the general public. A retrospective review of medical records of persons with acute MI showed that they were less likely than matched controls to have been treated during the preceding 3 years with tetracycline or quinolone antibiotics, which are active against C. pneumoniae. To date, however, prospective studies have not shown an association between the presence of IgG antibody to C. pneumoniae and an increased risk of atherothrombotic disease. Researchers have speculated that infection with C. pneumoniae may be one of several factors capable of initiating changes that culminate in atherosclerosis, or that reinfection may trigger coronary atherothrombosis. Antibody to C. pneumoniae is also found in persons with severe hypertension at about twice the incidence rate for the general public. In addition, the organism has been detected in microglia and astroglia of the hippocampus and temporal cortex in persons with late-onset Alzheimer disease with much greater frequency than in normal brains.

- C. psittaci bacterial organisms that resemble C. trachomatis, but that form loosely bound intracytoplasmic microcolonies up to 12 μm in diameter, do not produce glycogen in sufficient quantity to be detected by iodine stains, and are not susceptible to sulfadiazine. Various strains of this species cause psittacosis in humans and ornithosis in nonpsittacine birds; pneumonitis in cattle, sheep, swine, cats, goats, and horses; enzootic abortion of ewes; bovine sporadic encephalomyelitis; enteritis of calves; epizootic chlamydiosis of muskrats and hares; encephalitis of opossum; and conjunctivitis of cattle, sheep, and guinea pig s.

- C. trachomatis spherical nonmotile bacteria that are obligatory intracellular organisms; they form compact intracytoplasmic microcolonies up to 10 μm in diameter which (by division) give rise to infectious spherules 0.3 μm or more in diameter, accumulate glycogen for a limited period in sufficient quantity to be detected by iodine stain, and are usually susceptible to sulfadiazine, tetracycline, and quinalones; various strains of this species cause trachoma, inclusion and neonatal conjunctivitis, lymphogranuloma venereum, mouse pneumonitis, nonspecific urethritis, epididymitis, cervicitis, salpingitis, proctitis, and pneumonia; chief agent of bacterial sexually transmitted diseases in the U.S.; the type species of the genus Chlamy dia.

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chla·myd·ia klə-'mid-ē-ə n

1) cap the type genus of the family Chlamydiaceae comprising coccoid to spherical gram-negative intracellular parasitic bacteria and including one (C. trachomatis) that causes or is associated with various diseases of the eye and genitourinary tract including trachoma, lymphogranuloma venereum, cervicitis, and some forms of nongonococcal urethritis

2) pl -i·ae -ē-.ē, -.ī also -ias

a) a bacterium of the genus Chlamydia

b) an infection or disease caused by chlamydiae

chla·myd·ial -ē-əl adj

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n.

a genus of Gram-negative bacteria that are obligate intracellular parasites in humans and other animals, in which they cause disease. Chlamydia psittaci causes psittacosis, and C. trachomatis is the causative agent of the eye disease trachoma. Some strains of Chlamydia, especially C. trachomatis, are a common cause of sexually transmitted infections, being responsible for nonspecific urethritis in men, pelvic inflammatory disease in women, and inclusion conjunctivitis in the newborn. C. pneumoniae causes pneumonia.

• chlamydial adj.

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Chla·my·dia (klə-midґe-ə) [Gr. chlamys, gen. chlamydos cloak] a genus of bacteria of the family Chlamydiaceae, consisting of gram-negative, glycogen-producing, coccoid organisms that multiply only within a host cell and have a unique growth cycle (see Chlamydiales). They are common pathogens. Some former members of this genus are now classified in the genus Chlamydophila. The type species is C. trachoґmatis.