chlamydia: Definition and Much More from Answers.com
- ️Wed Jul 01 2015
A genus of bacteria with a growth cycle differing from that of all other microorganisms. Chlamydiae grow only in living cells and cannot be cultured on artificial media. Although capable of synthesizing macromolecules, they have no system for generating energy; the host cell's energy system fuels the chlamydial metabolic processes. The genome is relatively small; the genomes of C. pneumoniae and C. trachomatis have been completely sequenced.
The chlamydial infectious particle, called the elementary body, is round and about 350–450 nanometers in diameter. It enters a susceptible host cell and changes to a metabolically active and larger (approximately 800–1000 nm in diameter) reticulate body that divides by binary fission. The entire growth cycle occurs within a vacuole that segregates the chlamydia from the cytoplasm of the host cell. The reticulate bodies change back to elementary bodies, and then the cell lyses and the infectious particles are released. The growth cycle takes about 48 h.
Human diseases are caused by three species of Chlamydia. Chlamydia trachomatis is almost exclusively a human pathogen, and one of the most common. Infections occur in two distinct epidemiologic patterns. In many developing countries, C. trachomatis causes trachoma, a chronic follicular keratoconjunctivitis. It is the world's leading cause of preventable blindness, affecting approximately 500 million people. In areas where this condition is highly endemic, virtually the entire population is infected within the first few years of life. Most active infections are found in childhood. By age 60, more than 20% of a population can be blinded as a result of trachoma. See also Eye disorders.
Chlamydia trachomatis is the most common sexually transmitted bacterial pathogen; an estimated 3–4 million cases occur each year in the United States, and there are close to 90 million worldwide. The most common manifestation is nongonococcal urethritis in males. The cervix is the most commonly infected site in women. Ascending infections can occur in either sex, resulting in epididymitis in males or endometritis and salpingitis in females. Chlamydial infection of the fallopian tube can cause late consequences such as infertility and ectopic pregnancy, even though the earlier infection is asymptomatic. The infant passing through the infected birth canal can acquire the infection and may develop either conjunctivitis or pneumonia. A more invasive form of C. trachomatis causes a systemic sexually transmitted disease called lymphogranuloma venereum. See also Sexually transmitted diseases.
Chlamydia psittaci is virtually ubiquitous among avian species and is a common pathogen among lower mammals. It is economically important in many countries as a cause of abortion in sheep, cattle, and goats. It causes considerable morbidity and mortality in poultry. Chlamydia psittaci can infect humans, causing the disease psittacosis. Psittacosis can occur as pneumonia or a febrile toxic disease without respiratory symptoms.
Chlamydia pneumoniae appears to be a human pathogen with no animal reservoir. It is of worldwide distribution and may be the most common human chlamydial infection. It appears to be an important cause of respiratory disease.
Azithromycin is the drug of choice for uncomplicated chlamydial infection of the genital tract. Two therapeutic agents require longer treatment regimens: doxycycline, a tetracycline antibiotic, is the first alternate treatment; erythromycin may be used for those who are tetracycline-intolerant, as well as for pregnant women or young children. See also Medical bacteriology.
Definition
Chlamydia is the most common sexually transmitted disease (STD) in the United States, with about three million new cases diagnosed in the country each year. The disease is caused by a bacterium called Chlamydia trachomatis. The following areas in the body can be affected:
- cervix
- fallopian tubes, which carry ova (eggs) from the ovaries to the uterus
- urethra, which carries urine from the bladder to outside the body
- epididymis, a small organ attached to the testicles that is responsible for sperm production
- prostate gland, a gland at the base of the penis which provides nutrients for sperm
- anus
- throat
- eyes
In addition, Chlamydia trachomatis also causes lung and eye infections in newborns whose mothers have a chlamydial infection during the last part of their pregnancy.
Description
Chlamydia is most often found in sexually active adolescents aged 15–19. Data gathered by the Centers for Disease Control (CDC) suggest that sexually active girls in this age group may account for up to 46% of chlamydial infections.
According to the CDC, approximately 40% of women infected with chlamydia will develop pelvic inflammatory disease (PID). If untreated, 18% of women with PID will have chronic inflammatory pain. In addition, chlamydia may cause extensive damage to the fallopian tubes. Scarring can block the tube and prevent the egg from being fertilized. As a result, one of every five women with PID will not be able to conceive. Tube scarring may also cause the fertilized egg to be trapped inside the tube, unable to reach the uterus. When the fertilized egg develops inside the tube rather than in the uterus, the condition is called tubal pregnancy. The condition is potentially fatal if the tube ruptures. In America, tubal pregnancy is the number one cause of death of women in early pregnancy.
Causes & Symptoms
Cause
Chlamydia is caused by a bacterial parasite called Chlamydia trachomatis. The organism lives inside humans, who act as hosts. It is dependent on humans for energy because it is unable to produce energy for itself. C. trachomatis often causes genital and urinary tract infections in sexually active men and women.
Mode of Transmission
A person can be infected with C. trachomatis by:
- having sex (oral, genital, or anal) with an infected partner
- sharing infected sex toys
- passing through the infected birth canal of a mother who has chlamydia
- sex abuse in children
Risk Factors
The following are risk factors for contracting chlamydia infections:
- Age. Young sexually active people aged 15–19 are most frequently affected.
- Race. Blacks contract this disease more often than whites or Hispanics.
- Marital status. Chlamydia is most often found in single women. Married women have the lowest risk.
- Behavioral factors. Douching increases risk of chlamydial infections. Smoking also increases one's risk of contracting this disease. Those who have sex with many different partners or with strangers are at high risk. Also at increased risk are those who have unprotected sex with partners of unknown disease status. Previous induced abortions also increase a woman's chance of getting this disease.
- Socio-economic status. Poor, uneducated women living in big cities are more often affected by this disease.
- Postpartum period. Increased risk of contracting chlamydia is observed during the period immediately
after giving birth or undergoing an induced abortion. This is because the cervix is not entirely closed, allowing more chance for becoming infected.
Symptoms
Approximately 75% of women do not have symptoms. If a woman is going to have any symptoms, they should develop one to three weeks after she is infected. Her symptoms may include:
- burning pain during urination
- more frequent urination
- abnormal vaginal discharge
- dull pelvic pain
- bleeding between periods and after sexual intercourse
- menstrual bleeding that is heavier than usual
- more painful periods
Chlamydia infection in men may develop in the urethra, epididymis and/or the prostate. Approximately 50% of infected men do not have any symptoms. If he is going to have symptoms, they should develop one to three weeks after he is infected. His symptoms may include:
- burning pain during urination
- more frequent urination
- white or yellow discharge from the penis
- redness at the tip of the penis
- itchy or irritated urethra (urethritis)
- pain and swelling in the testicles (epididymitis)
- pain between the scrotum and anal area and difficult and frequent urination (prostatitis)
On rare occasions, chlamydia infection in men and women can develop outside of the genital areas. These patients may have infections at the following sites:
- the eyes (due to a contaminated hand touching the eyes): itching, redness and itching of the eyelids
- the throat (following oral sex with infected men): throat irritation or no symptoms
- the anus (following anal intercourse with infected men): rectal bleeding, mucous rectal discharge, diarrhea, and pain with bowel movement.
Diagnosis
Diagnosis is based on patients' history, laboratory testing for chlamydia, and physical exam for men and pelvic exam for women to determine if the patient is infected and/or the extent of infection.
There are several tests available for chlamydial infection. They often require swipes from the site of infection or urine samples. Tests for chlamydia include:
- Cell culture test. This old test is reliable but requires 48–72 hours to complete. It is being replaced by faster and more convenient tests. In 2001, the U.S. Food and Drug Administration (FDA) receommended routine screening for chlamydia among sexually active young women. One year later, they approved a new test called ThinPrep, a new type of Pap smear that allows doctors to screen for chlamydia, gonorrhea, and the human papillomavirus at the same time women have annual pap exams for cervical cancer.
- Direct fluorescent antibody (DFA) staining. This test is faster than the traditional culture test.
- Enzyme immunoassay (EIA). It is easy to perform and also faster than the traditional culture test but is not as accurate.
- DNA probe. This test is expensive but is more specific and convenient than culture, EIA, or DFA tests. Genital swipe samples are not necessary. Urine tests can provide accurate results.
- Nucleic acid amplification (PCR and LCR) tests. These tests look for genetic material of the organism. These are the tests of choice because they are the most sensitive (more than 90% accurate) and the most specific. They are also convenient because they can be performed on urine samples and do not require a pelvic exam.
In 2002, a presentation to gynecologists pointed out that more doctors should assume some overlap when patients present with symptoms of urinary tract infections. These may signal hidden chlamydia as well. In fact, the two conditions often can be present at the same time.
Treatment
Alternative therapy should be complementary to antibiotic therapy. Because of the potentially serious nature of this disease, patients should first consult an allopathic physician to start antibiotic treatment for infections. Traditional medicine is better equipped to quickly eradicate the infection while alternative treatments can help the body fight the disease and relieve symptoms associated with this disease. Some alternative treatments include nutritional therapy, herbal remedies, traditional Chinese medicine, and homeopathy.
Nutritional Therapy
The following dietary changes may be helpful:
- Following a low-fat, high-fiber diet. The diet should include a variety of fresh fruits and vegetables. These foods contain high amounts of phytonutrients and essential vitamins that help keep the body strong and stimulate the immune system to fight infections.
- Limited intake of fat, sugar, highly processed foods, caffeine, and alcohol, which depresses the immune function.
- Taking a multivitamin/mineral supplement daily.
- Drinking cranberry juice. Cranberry juice helps prevent urinary tract infections.
- Taking acidophilus pills to prevent yeast infections while on antibiotics.
- Eating fresh garlic or taking garlic pills to help fight infection.
Herbal Treatment
Echinacea and berberine-containing herbs such as saw palmetto (Serenoa repens) and goldenseal are natural antibiotics. These herbs can assist the action of prescription antibiotics.
Traditional Chinese Medicine
An experienced Chinese herbalist will prepare a specific herbal mixture based on a patient's specific condition and symptoms.
Homeopathy
A homeopathic practitioner may prescribe a patient-specific remedy to help reduce some of the symptoms associated with disease. Remedies for chlamydial symptoms include Cannabis sativa, Cantharis, and Salidago virga.
Allopathic Treatment
Once detected, chlamydia can be easily treated with antibiotics. However, if not detected early enough, scarring of fallopian tubes (and resulting infertility) may not be preventable. The two most commonly used drugs are azithromycin and doxycycline. Azithromycin is a more expensive drug but is much more convenient to administer. Only one dose is needed to treat the disease. Doxycycline is cheaper but needs to be taken twice a day for more than seven days. Because patients tend to stop taking drugs after a few days, doxycycline is not as effective as azithromycin. Therefore, many doctors prefer to give azithromycin. Patients are advised to refrain from sex for a full week after taking azithromycin or until they finish doxycycline treatment.
An infected person should contact all partners within the last two months so that they can be treated for chlamydia.
Infected pregnant women should be given erythromycin for seven days, instead of other drugs, because this drug is safer during pregnancy.
Follow-up testing is done four weeks after drug treatment to see if the infection is eradicated. If tests continues to be positive, the patient will be given another course of antibiotics.
Expected Results
A woman's prognosis depends on the duration of infection, whether the infection has spread through the uterus and the fallopian tubes, and the number of previous chlamydial infections. If caught early, the disease can be completely cured with antibiotic treatment in seven days. However, if left untreated, chlamydia can spread through the uterus to the fallopian tubes and cause chronic pelvic inflammatory disease. Infertility may occur as a result of serious damage to the female reproductive tract. Potentially fatal tubal pregnancy is also a risk.
Prevention
Prevention is the most important means of stopping the spread of this disease. The following practices are recommended to prevent the spread of this and other sexually transmitted diseases:
- Abstinence. Abstinence is the only 100% way to prevent chlamydia and other STD infections.
- Monogamy. Having a mutually monogamous relationship with an uninfected partner reduces the chance of getting STD infections.
- Avoiding a sexual relationship with an unknown partner or a partner whose infection status is unknown.
- If having sex with an unknown partner, using a barrier contraceptive such as a condom (for men) or diaphragm (for women) is recommended. However, condoms (or diaphragms) are not 100% effective against chlamydia or other STDs.
- Refraining from douching.
- Avoiding sex soon after giving birth or undergoing an induced abortion.
- Getting tested for chlamydia at yearly pelvic examinations.
Resources
Books
"Chlamydia." In The Medical Advisor: The Complete Guide to Alternative & Conventional Treatment, home ed. Alexandria, VA: Time-Life, Inc., 1997.
"Chlamydia." In Reader's Digest Guide to Medical Cures & Treatments. Pleasantville, NY: Reader's Digest Assn., Inc., 1996.
"Chlamydial Infections." In 1997 Report of the Committee on Infectious Diseases, 2nd ed. Elk Grove Village, IL: American Academy of Pediatrics, 1997.
Jones, Robert B. and Byron E. Batteiger. "Introduction to Chlamydial Diseases." In Mandell, Douglas & Bennett's Principles & Practice of Infectious Diseases. 5th ed. Philadelphia: W. B. Saunders Co., 1999. http://home.mdconsult.com.
"Section I. Screening Part D. Infectious Diseases. Screening for Chlamydial Infections-Including Ocular Prophylaxis in Newborns." In Guide to Clinical Preventive Services: Report of the U. S. Preventive Services Task Force. 2nd ed. Philadelphia: Lippincott Williams & Wilkins, 1996. http://home.mdconsult.com.
The Burton Goldberg Group. "Sexually Transmitted Diseases." In Alternative Medicine: The Definitive Guide. Tiburon, CA: Future Medicine Publishing, Inc., 1999.
Tuomala, Ruth E. and Katherine T. Chen. "Gynecologic Infections. Part I." Kistner's Gynecology & Women's Health. 7th ed. St. Louis, MO: Mosby, Inc., 1999.
Zand, Janet, Allan N. Spreen and James B. LaValle. "Chlamydia." In Smart Medicine for Healthier Living. Garden City Park, NY: Avery Publishing Group, 1999.
Periodicals
"FDA: ThinPrep can Detect Chlamydia, Gonorrhea." TB & Outbreaks Week (July 2, 2002): 15.
Johnson, Kate. "Urinary Symptoms? Test for Chlamydia and UTI (Not Just Vaginal Symptoms)." OB GYN News (August 15, 2002): 12.
Torrey, Brian. "FDA Approval of Chlamydia and Gonorrhea Tests." American Family Physician (August 15, 2002): 690.
Organizations
CDC National STDs Hotline. (800) 227-8922.
NIH's National Institute of Allergy and Infectious Diseases. NIAID Office of Communications, 31 Center Drive (MSC-2520), Building 31, Room 7A50, Bethesda, MD 208922520. http://www.niaid.nih.gov/publications/stds.htm.
Other
Centers for Disease Control and Prevention. "CDC Fact Sheet: Some Facts about Chlamydia." WebMD.http://webmd.lycos.com/content/dmk/dmk_article_58818.
Nordenburg, Tamar. "Chlamydia's Quick Cure." WebMD.http://webmd.lycos.com/content/dmk/dmk_article_5462446.
Peeling, Rosanna W. "Chlamydiae as Pathogens: New Species and New Issues." Medscape.http://www.medscape.com.
U.S. Department of Health and Human Services. "Counseling to Prevent HIV Infection and Other Sexually Transmitted Diseases." WebMD.http://webmd.lycos.com/content/dmk/dmk_article_5462254.
[Article by: Mai Tran; Teresa G. Odle]
Chlamydia is a common sexually transmitted disease (STD) caused by Chlamydia trachomatis, a bacterium. Chlamydia can be transmitted during vaginal, anal, or oral sex. An estimated 3 million Americans are infected with chlamydia each year. Three-quarters of infected women and half of infected men have no symptoms. Sexually active girls and young women are especially susceptible to chlamydia because the cells that form the lining of the immature cervix are easily invaded by the bacteria. Women with symptoms might have an abnormal vaginal discharge or a burning sensation when urinating. When the infection spreads from the cervix to the fallopian tubes, some women still have no symptoms; others have lower abdominal pain, low back pain, nausea, fever, pain during intercourse, and bleeding between menstrual periods. Whenever the infection spreads past the cervix, permanent and irreversible damage can occur to the fallopian tubes, uterus, and tissues surrounding the ovaries. This damage can lead to chronic pelvic pain, infertility, and potentially fatal ectopic pregnancy.
Widely available laboratory tests can accurately detect chlamydia bacteria in a urine sample. Chlamydia can be treated and cured with antibiotics. Persons who engage in sexual behaviors that place them at risk of STDs should use latex or polyurethane condoms every time they have sex, limit the number of sex partners, and not alternate partners. All young, sexually active, unmarried persons who do not use condoms every time they have sex should be screened for chlamydia yearly. Infected persons should notify all sex partners so they can receive treatment.
(SEE ALSO: Sexually Transmitted Diseases)
Bibliography
Centers for Disease Control and Prevention (1998). "1998 Guidelines for Treatment of Sexually Transmitted Diseases." Morbidity and Mortality Weekly Report 47 (RR-1):53–59.
Stamm, W. E. (1999). "Chlamydia trachomatis Infections of the Adult." In Sexually Transmitted Diseases, 3rd edition, eds. K. Holmes, P. Mardh, P. Sparling et al. New York: McGraw-Hill.
— ALLISON L. GREENSPAN; JOEL R. GREENSPAN
Classification & external resources
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|---|---|
| Pap smear showing C. trachomatis (H&E stain) | |
| ICD-10 | A55.-A56.8, A70.-A74.9 |
| ICD-9 | 099.41, 483.1 |
| DiseasesDB | 2384 |
| eMedicine | med/340 |
Chlamydia is a common term for Chlamydiae. This term derives from the name of the bacterial genus Chlamydia in the family Chlamydiaceae, order Chlamydiales, class and phylum Chlamydiae, ultimately from Greek χλαμύδος "cloak". There are two genera in Chlamydiaceae: Chlamydia and Chlamydophila. There is still some controversy surrounding the establishment of a second genus as the rationale for this is poorly justified. The genus Chlamydia includes three species: C. trachomatis, C. muridarum, and C. suis. C. trachomatis infection is described below.
Chlamydia trachomatis is a major infectious cause of human eye and genital disease. C. trachomatis is naturally found living only inside human cells and is one of the most common sexually transmitted infections in people worldwide — about 2.8 million cases of chlamydia infection occur in the United States each year.[1] Not all infected people exhibit symptoms of infection. Between half and three-quarters of all women who have chlamydia have no symptoms and do not know that they are infected. It can be serious but is easily cured with appropriate antibiotics if detected in time. Equally important, chlamydia infection of the eye is the most common cause of preventable blindness in the world. Blindness occurs as a complication of trachoma (chlamydia conjunctivitis).[2]
There are many other species of Chlamydiae that live in the cells of animals (including humans), insects, or protozoa. Two of these species cause lung infection in humans: Chlamydia pneumoniae and Chlamydophila psittaci.
Symptoms
Chlamydia is an asymptomatic disease for 50-70% of the female population. Of those who have an asymptomatic infection that is not detected by their doctor, approximately half will develop pelvic inflammatory disease (PID), a generic term for infection of the uterus, fallopian tubes, and/or ovaries. PID can cause scarring inside the reproductive organs, which can later cause serious complications, including chronic pelvic pain, difficulty becoming pregnant, ectopic (tubal) pregnancy, and other dangerous complications of pregnancy. Chlamydia causes 250,000 to 500,000 cases of PID every year in the U.S. Women infected with chlamydia are up to five times more likely to become infected with HIV, if exposed.[1]
Chlamydia is known as the "Silent Epidemic" because in women, it may not cause any symptoms and will linger for months or years before being discovered. Symptoms that may occur include: unusual vaginal bleeding or discharge, pain in the abdomen, painful sexual intercourse, fever, painful urination or the urge to urinate more frequently than usual.
In men, chlamydia is symptomatic in greater than 90% of cases. Symptoms that may occur include: a painful or burning sensation when urinating, an unusual discharge from the penis, swollen or tender testicles, or fever. Discharge, or the purulent exudate, is generally less viscous and lighter in color than for gonorrhea.
Male patients may develop a white, cloudy or watery discharge (shown) from the tip of the penis.
Chlamydia in men can spread to the testicles, causing epididymitis, which can cause sterility if not treated within 6 to 8 weeks. Chlamydia causes more than 250,000 cases of epididymitis in the USA each year.
Chlamydia may also cause reactive arthritis, especially in young men. (Some forms of reactive arthritis formerly were known as Reiter's syndrome. The latter term has fallen out of favor owing to revelations about Hans Reiter's Nazi past and in particular his alleged active participation in horrific human experiments in concentration camps.) About 15,000 men develop reactive arthritis due to chlamydia infection each year in the USA, and about 5,000 are permanently affected by it.
As many as half of all infants born to mothers with chlamydia will be born with the disease. Chlamydia can affect infants by causing spontaneous abortion; premature birth; conjunctivitis, which may lead to blindness; and pneumonia. Conjunctivitis due to chlamydia typically occurs one week after birth (Compare with chemical causes (within hours) or gonorrhea (2-5 days)).
Detection
1. Heavy bleeding on periods. The diagnosis of genital chlamydial infections evolved rapidly from the 1990s through 2006. Nucleic acid amplification tests (NAAT), such as polymerase chain reaction (PCR), transcription mediated amplification (TMA), and the DNA strand displacement assay (SDA) now are the mainstays. As of January 2007, the most commonly used and widely studied chlamydia NAATs in the US and many other industrialized countries are Aptima (Gen-Probe), Probe-Tec (Becton-Dickinson), and Amplicor (Roche). The Aptima Combo II assay tests simltaneously for C. trachomatis and Neisseria gonorrhoeae, the cause of gonorrhea. NAAT for chlamydia may be performed on swab specimens collected from the cervix (women) or urethra (men), on self-collected vaginal swabs, or on voided urine. Urine and self-collected swab testing facilitates the performance of screening tests in settings where genital examination is impractical. At present, the NAATs have regulatory approval only for testing urogenital specimens, although rapidly evolving research indicates that the Aptima test may give reliable results on rectal specimens.
Because of improved test accuracy, ease of specimen management, convenience in specimen management, and ease of screening sexually active men and women, the NAATs have largely replaced culture, the historic gold standard for chlamydia diagnosis, and the non-amplified probe tests, such as Pace II (Gen-Probe). The latter test is relatively insensitive, successfully detecting only 60-80% of infections in asymptomatic women, and occasionally giving falsely positive results. Culture remains useful in selected circumstances and is currently the only assay approved for testing non-genital specimens.
Treatment
Chlamydia trachomatis inclusion bodies (brown) in a McCoy cell culture.
C. trachomatis infection can be effectively cured with antibiotics once it is detected. Current Centers for Disease Control guidelines provide for the following treatments:
- Azithromycin 1 gram oral as a single dose, or
- Doxycycline 100 milligrams twice daily for seven days.
- Tetracycline
- Erythromycin
Untested Treatments
- Ciprofloxacin 500 milligrams twice daily for 3 days.
- (Although this is not an approved method of treatment, as it is shown to be ineffective and may simply delay symptoms.)
β-lactams are not suitable drugs for the treatment of chlamydia. While they have the ability to halt growth of the organism (i.e. are microbistatic), these antibiotics do not eliminate the bacteria. Once treatment is stopped, the bacteria will begin to grow once more. (See below for Persistence.)
Pathophysiology
Chlamydial Life Cycle Chlamydiae are obligate, intracellular bacterial pathogens, which means they are unable to replicate outside of a host cell. However, to disseminate effectively, these pathogens have evolved a unique biphasic life cycle wherein they alternate between two functionally and morphologically distinct forms. The elementary body (EB) is infectious but metabolically inert, much like a spore, and can survive for limited amounts of time in the extracellular milieu. Once the EB attaches to a susceptible host cell, it mediates its own internalization through pathogen-specified mechanisms (via type III secretion system) that allows for the recruitment of actin with subsequent engulfment of the bacterium. The internalized EB, within a membrane-bound compartment, immediately begins differentiation into the reticulate body (RB). RBs are metabolically active but non-infectious and, in many regards, resemble normal replicating bacteria. The intracellular bacteria rapidly modifies its membrane-bound compartment into the so-called chlamydial inclusion so as to prevent phagosome-lysosome fusion. According to published data, the inclusion has no interactions with the endocytic pathway and apparently inserts itself into the exocytic pathway as it retains the ability to intercept sphingomyelin-containing vesicles. To date, no one has been able to detect a host cell protein that is trafficked to the inclusion through the exocytic pathway. As the RBs replicate, the inclusion grows as well to accommodate the increasing numbers of organisms. Through unknown mechanisms, RBs begin a differentiation program back to the infectious EBs, which are released from the host cell to initiate a new round of infection. Because of their obligate intracellular nature, chlamydiae has no tractable genetic system, like E. coli, which makes this and related organisms difficult to investigate.
Persistence Chlamydiae have the ability to establish long-term associations with host cells. When an infected host cell is starved for various nutrients such as amino acids (e.g. tryptophan), iron, or vitamins, this has a negative consequence for chlamydiae since the organism is dependent on the host cell for these nutrients. The starved chlamydiae enter a persistent growth state wherein they stop cell division and become morphologically aberrant by increasing in size. Persistent organisms remain viable as they are capable of returning to a normal growth state once conditions in the host cell improve. There is much debate as to whether persistence has in vivo relevance. Many believe that persistent chlamydiae are the cause of chronic chlamydial diseases. Some antibiotics such as β-lactams can also induce a persistent-like growth state, which can contribute to the chronicity of chlamydial diseases.
Diseases caused by Chlamydia trachomatis
Conjunctivitis due to chlamydia.
Chlamydia trachomatis can cause the following conditions:
Recent genetic discoveries
Recent phylogenetic studies have revealed that chlamydia shares a common ancestor with modern plants, and retains unusual plant-like traits (both genetically and physiologically). In particular, the enzyme L,L-diaminopimelate aminotransferase, which is related to lysine production in plants, is also linked with the construction of chlamydia's cell wall. The genetic encoding for the enzymes is remarkably similar in plants and chlamydia, demonstrating a close common ancestry.
This unexpected discovery may help scientists develop new treatment avenues: if scientists could find a safe and effective inhibitor of L,L-diaminopimelate aminotransferase, they might have a highly effective and extremely specific new antibiotic against chlamydia.
References
- ^ Chlamydia fact sheet from the Centers for Disease Control and Prevention
- ^ Belland R, Ojcius D, Byrne G (2004). "Chlamydia". Nat Rev Microbiol 2 (7): 530 – 1. PMID 15248311.
External links
Wikimedia Commons has media related to:
- "Chlamydia: Questions and Answers" from Planned Parenthood"
- NetDoctor Chlamydia fact sheet
- Links to chlamydia pictures (Hardin MD/Univ of Iowa)
- Resources for research on chlamydial infections
- eMedicine: Chlamydial Genitourinary Infections
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