Chlamydia Origin and Evolution
Recent phylogenetic studies have shown that Chlamydia and cyanobacteria, the community that includes the endosymbiont ancestor to modern plants' chloroplasts, have a shared ancestor. As a result, Chlamydia maintains unusual plant-like characteristics, both genetically and physiologically. The enzyme L, L-diaminopimelate aminotransferase, which is involved in plant lysine processing, is also involved in the formation of chlamydial cell walls. Plants, cyanobacteria, and Chlamydia all have remarkably similar genetic encoding for enzymes, indicating a nearly shared ancestor.
What is the Chlamydia Causative Agent?
The bacterium Chlamydia trachomatis is the chlamydia causative agent, which is a sexually transmitted infection. The majority of people who are infected show no signs or symptoms. When signs do emerge, they can appear just a few weeks after infection; the incubation period between exposure and the ability to infect others is estimated to be two to six weeks.
Chlamydia Classification
Domain: Bacteria
Phylum: Chlamydiae
Class: Chlamydiae
Order: Chlamydiales
Family: Chlamydiaceae
Genus: Chlamydia
Chlamydiae were once thought to be viruses because of their reliance on host biosynthetic machinery; however, they have a cell wall and contain DNA, RNA, and ribosomes, so they are now known as bacteria that causes chlamydia. Chlamydia is the only genus in the group (order: Chlamydiales, class: Chlamydiaceae). The species C. trachomatis and C. psittaci belong to the chlamydia genus, as does a new organism, the TWAR organism, which was recently proposed as a third species (C. pneumoniae). Human disease is caused by all three animals. Chlamydia psittaci infects a wide range of birds and rodents, while Chlamydia trachomatis is primarily found in humans.
Chlamydia Organism Developmental Cycle
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An elementary body and a reticulate body are two forms of Chlamydia bacteria. The nonreplicating infectious particle produced when infected cells rupture is known as the elementary body. It is similar to a spore and is responsible for the bacteria's ability to spread from person to person. The diameter of the elementary body can range from 0.25 to 0.30 m. A rigid cell wall protects this type (hence the combining form chlamyd- in the genus name). When exposed to target cells, the elementary body causes its own endocytosis. Typically, one phagolysosome creates 100–1000 elementary bodies.
Chlamydia may also take the form of a reticulate body, which is an intracytoplasmic form that plays an important role in the bacteria's replication and development. The reticulate body is significantly larger than the elementary body, with a maximum diameter of 0.6 m and a minimum diameter of 0.5 m. It is devoid of a cell wall. Reticulate bodies behave as inclusions in the cell when stained with iodine. The reticulate body stores the DNA genome, proteins, and ribosomes. This happens as a part of the bacteria's growth cycle. The reticular body is the structure where the chlamydial genome is translated into RNA, proteins are synthesised, and DNA is replicated.
The fusion lasts about three hours, with a 21-day incubation period possible. The reticulate body reverts to its elementary form after division and is released by the cell through exocytosis.
The infectious elementary body (EB) grows into a noninfectious reticulate body (RB) inside a cytoplasmic vacuole in the infected cell, according to studies on the growth cycle of Chlamydia trachomatis and Chlamydia psittaci in cell cultures in vitro. After the infectious particle enters the infected cell, there is a 20-hour eclipse period during which the infectious particle transforms into a reticulate body. After 36 to 50 hours after infection, the yield of chlamydial elementary bodies reaches its peak.
HctA and HctB, two histone-like proteins, play a part in regulating the differentiation of the two cell types. Until late RB to EB re-differentiation, the expression of HctA is tightly regulated and repressed by IhtA, a small non-coding RNA. Across Chlamydia species, the IhtA RNA is conserved.
Chlamydia Genus Symptoms and Pathology
Chlamydia genus symptoms: The majority of chlamydial infections are asymptomatic. Men, on the other hand, are more likely to experience a burning sensation while urinating. Odour and itching are two potential symptoms for women. As the infection progresses, both sexes may experience increased sebum development, which results in greasy sweat, an oilier skin, and can be misdiagnosed as acne eruptions rather than the body's secret battle to protect itself from an STD. Anyone who has had sexual contact with a possibly infected person could be given one of many tests to diagnose the disease.
Culture tests and nonculture tests can also be used to diagnose Chlamydia. Fluorescent monoclonal antibody tests, enzyme immunoassays, DNA probes, rapid Chlamydia tests, and leukocyte esterase tests are the most popular nonculture tests. The first test detects the main outer membrane protein (MOMP), while the second detects a coloured substance that has been transformed by an enzyme-linked to an antibody. Antibodies against the MOMP are used in rapid Chlamydia tests, while enzymes released by leukocytes containing the bacteria in the urine are detected in leukocyte esterase tests.
Chlamydia Bacteria Diseases
Ocular Infections: Trachoma and inclusion conjunctivitis are caused by Chlamydia trachomatis. The growth of follicles and inflamed conjunctivae are hallmarks of trachoma. Repeated infections can cause the cornea to become cloudy and vascularized, resulting in blindness. Inclusion conjunctivitis is a less severe inflammatory conjunctivitis that produces a purulent discharge.
Genital Infections: Nongonococcal urethritis in men and acute salpingitis and cervicitis in women are both infections caused by C trachomatis strains. Other strains cause lymphogranuloma venereum, a venereal disease characterised by genital lesions and involvement of regional lymph nodes (buboes).
Respiratory Infections: Psittacosis is an influenza-like illness caused by Chlamydia psittaci. In humans, Chlamydia pneumoniae (the TWAR organism) causes atypical pneumonitis.
Chlamydia Examples of Signs and Symptoms
Genital Diseases
Women -
Chlamydial infection of the cervix (womb's neck) is a sexually transmitted infection that affects about 70% of women without causing any symptoms. The infection is spread through vaginal, anal, or oral sex. About half of those that have an asymptomatic infection that goes unnoticed by their doctor will experience pelvic inflammatory disease (PID), a term for infection of the uterus, fallopian tubes, and/or ovaries.
PID can cause scarring of the reproductive organs, which can lead to serious complications such as constant pelvic pain, inability to conceive, ectopic (tubal) pregnancy, and other severe pregnancy complications.
Abnormal vaginal bleeding or discharge, stomach pain, painful sexual intercourse, fever, painful urination, or the need to urinate more often than usual are some of the signs and symptoms (urinary urgency). Screening is recommended for sexually active women who are not pregnant, particularly those under the age of 25 and those who are at risk of infection.
A history of chlamydial infection or another sexually transmitted infection, new or multiple sexual partners, and inconsistent condom usage are all risk factors.
Men -
In around half of all cases, men with a chlamydial infection experience signs of infectious urethral inflammation. A painful or burning feeling when urinating, an irregular discharge from the penis, testicular pain or swelling, or a fever are all possible symptoms.
Chlamydia in men can spread to the testicles, causing epididymitis, which can lead to sterility in extreme cases if not treated. Chlamydia can also cause prostatic inflammation in men, but the exact role it plays in prostatitis is difficult to determine due to urethritis contamination.
Eye Diseases
Chlamydia trachomatis causes trachoma, a chronic conjunctivitis. Fingers, mutual towels or cloths, coughing and sneezing, and eye-seeking flies may all spread the infection from one eye to the next. Mucopurulent ocular discharge, itching, redness, and lid swelling are all symptoms. Childbirth can also cause chlamydia eye infection in newborns.
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Joints
In young men, chlamydia can cause reactive arthritis (the triad of arthritis, conjunctivitis, and urethral inflammation). It can affect both men and women, but it is more common in men.
Infants
Half of all children born to chlamydia-positive mothers would be infected with the disease. Chlamydia can cause spontaneous abortion, premature birth, conjunctivitis, which can cause blindness, and pneumonia in children. When compared to chemical causes (within hours) or gonorrhoea (2–5 days), conjunctivitis caused by chlamydia usually occurs one week after birth.
Chlamydia Diagnosis
The polymerase chain reaction (PCR), transcription-mediated amplification (TMA), and DNA strand displacement amplification (SDA) are now the mainstays of nucleic acid amplification studies (NAAT). NAAT for chlamydia may be done on swabs taken from the cervix (women) or the urethra (men), self-collected vaginal swabs, or voided urine. Regardless of whether a cervical swab or a urine specimen is used, NAAT has been estimated to have a sensitivity of around 90% and a specificity of around 99%.
Chlamydia Treatment
Antibiotics can effectively treat C. trachomatis infection. Azithromycin, doxycycline, erythromycin, levofloxacin, or ofloxacin are recommended by the guidelines. Doxycycline (100 mg twice a day for 7 days) is possibly more effective in men than azithromycin (1 g single dose), but evidence for antibiotics' relative efficacy in women is sketchy. Erythromycin or amoxicillin are two antibiotics that are prescribed during pregnancy.
Patient-delivered partner therapy (PDT or PDPT) is a treatment choice for sexual partners of those with chlamydia or gonorrhoea. It is the method of treating the sex partners of index cases by giving the patient prescriptions or medications to provide to his or her partner without the health care provider first testing the partner.
FAQs on Chlamydia
1. What is Chlamydia and which microorganism causes this infection?
Chlamydia is a common sexually transmitted infection (STI). It is caused by the bacterium Chlamydia trachomatis. While once thought to be a virus due to its reliance on host cells for replication, it is now classified as a bacterium because it possesses a cell wall, DNA, RNA, and ribosomes.
2. How is a Chlamydia infection transmitted between individuals?
Chlamydia is primarily transmitted through sexual contact, including vaginal, anal, or oral sex with an infected person. Transmission can occur even if ejaculation does not happen. Additionally, an infected mother can pass the infection to her infant during childbirth, potentially causing eye infections or pneumonia in the newborn.
3. What are the primary symptoms of Chlamydia in males and females?
Many Chlamydia infections are asymptomatic. When symptoms do appear, they can differ between sexes.
- In women: Symptoms may include abnormal vaginal discharge, abdominal pain, fever, painful urination, and pain during intercourse.
- In men: Symptoms can include a burning sensation during urination, discharge from the penis, and pain or swelling in one or both testicles.
4. Why are many Chlamydia infections asymptomatic, and what are the long-term risks if left untreated?
The majority of Chlamydia infections do not show any initial symptoms, which allows the infection to persist and be spread unknowingly. If left untreated, the consequences can be severe. In women, it can lead to Pelvic Inflammatory Disease (PID), causing scarring of the reproductive organs, chronic pelvic pain, ectopic pregnancies, and infertility. In men, untreated Chlamydia can spread to the testicles and cause epididymitis, which may lead to sterility.
5. What is the difference between the elementary body and the reticulate body in the Chlamydia life cycle?
The Chlamydia bacterium exists in two distinct forms during its life cycle:
- The elementary body (EB) is the small, infectious, non-replicating form. It has a rigid cell wall and is responsible for transmitting the infection between cells and people.
- The reticulate body (RB) is the larger, non-infectious, replicative form found inside the host cell. It lacks a rigid cell wall and is responsible for multiplying and synthesising new bacterial components before transforming back into elementary bodies to be released.
6. How is a Chlamydia infection diagnosed, and what is the standard treatment?
Diagnosis is primarily done using Nucleic Acid Amplification Tests (NAAT), which are highly sensitive and specific. These tests can be performed on urine samples or swabs from the cervix or urethra. Treatment for Chlamydia is effective and involves a course of antibiotics, such as Azithromycin or Doxycycline, as prescribed by a healthcare provider.
7. Can Chlamydia affect parts of the body other than the reproductive organs?
Yes, Chlamydia can cause infections in other parts of the body. Chlamydia trachomatis can cause trachoma, a chronic eye infection that can lead to blindness. It can also cause conjunctivitis in newborns born to infected mothers. Furthermore, it can trigger reactive arthritis, a condition causing inflammation in the joints, eyes, and urethra, which is more common in young men.
8. How does the Chlamydia bacterium exhibit unusual plant-like characteristics?
Phylogenetic studies suggest a shared evolutionary ancestor between Chlamydia and cyanobacteria, which are related to plant chloroplasts. This connection explains some of Chlamydia's unique plant-like traits. For instance, it uses an enzyme, L, L-diaminopimelate aminotransferase, for building its cell wall, an enzyme typically involved in lysine synthesis in plants. The genetic encoding for this and other enzymes shows a remarkable similarity to that found in plants.
