Chlamydia bacteria cause disease

2021-08-17 10:13 PM

Chlamydia has an affinity for epithelial cells of the mucosa. Basal body infiltrates epithelial cells by a hygroscopic mechanism

Chlamydia causes many different diseases, especially trachoma, Nicolas-Favre disease, parrot fever - bird fever (Ornithose-psittacose). Today, people also see Chlamydia as the causative agent of some diseases of the genitourinary tract - urinary tract, pelvic inflammatory disease, urethritis...

Biological characteristics

Chlamydia is an intracellular parasite, very small in size, but not a virus but a bacterium because:

Contains two types of nucleic acids: DNA and RNA.

Has a mucopeptide cell wall containing muramic acid.

Contains ribosomes and many metabolic enzymes.

They multiply in a dichotomous fashion

Sensitive to many antibiotics.

Morphology and development cycle

The development cycle follows between two bodies: the basal body 300 nm in diameter with a hard shell to survive release from the cell, and the reticulum over 1000 nm in diameter that is suitable for multiplication within the cell. These two bodies and other intermediate bodies become colored by Giemsa or Machiavello staining.

Chlamydia has an affinity for epithelial cells of the mucosa. The basal body infects epithelial cells by a hygroscopic mechanism. In about 8 hours the basal body reorganizes into the reticulum, which multiplies by schizophrenia. After 24 h the reticular bodies organize into basal bodies located within an inclusion body in the cytoplasm of the host cell. The cell then ruptures and releases the corpuscles. On cell culture, host cells die and self-lysis 40-60 hours after infection.

Chemical and metabolic properties

Chlamydia is strongly adapted to extracellular life and intracellular development. They are highly dependent on the host cell. They interfere with the protein and DNA synthesis of the host cell. They make their own macromolecules but use the metabolic energy of the host cell.

Antigen

There are 2 types of antigens:

Group-specific antigen: detectable in bacterial hydrolyzate.

Type-specific antigen: involves the outermost layer of the shell in intact Chlamydia.

Immune

Chlamydia tends to be chronic and has a relapsing course if left untreated. The chronic nature of the infection suggests an ineffective immune response, but usually, patients can limit or localize the disease without developing serious sequelae. The neutralizing antibody conjugated with the Chlamydia envelope antigen prevents the spread of Chlamydia infection to susceptible cells but does not inactivate the Chlamydia located within the cells. A person with a latent infection is relatively immune to reinfection but can continue to release bacteria and form a healthy carrier.

Classify

The causative agent of trachomatis is Chlamydia trachomatis.

The causative agent of venereal inguinal lymphadenitis (Lymphogranulomatose venerienne) is caused by Chlamydia lymphogranulomatosis.

Ornithose-psittacosis, the causative agent of parrot fever, is caused by Chlamydia psittacosis.

The causative agent of benign reticulocytosis is also known as cat scratch disease (Lymphoreticulose benign).

The causative agent of urethritis, cervical and conjunctivitis inclusions caused by Chlamydia oculogientalis

Some diseases caused by chlamydia

Disease caused by Chlamydia trachomatis

Chlamydia trachomatis consists of 18 serotypes designated from A to K and L1,2,3 . 

Trachoma disease

Trachoma conjunctivitis caused by Chlamydia trachomatis type AC. The disease is endemic in hot countries, worldwide, about 460 million people are infected, of which 6 million are completely blind.

The disease progresses through four stages:

Stage 1: Follicular conjunctivitis is often accompanied by bacterial superinfection.

Stage 2: granulomatous conjunctivitis.

Stage 3: There are mechanical complications such as scarring, ulceration, and superinfection.

Stage 4: Recovery with conjunctival scarring, corneal ulceration, and possible blindness if not treated aggressively.

Treatment with tetracycline ointment.

Urinary tract infections - sexually transmitted infections

Due to Chlamydia trachomatis type D - K. Currently the disease increases in the number and causes many serious complications. In men, the first manifestation is urethritis, which can then lead to epididymitis. In women, inflammation in the cervix, then leading to urethritis, if not treated well, will lead to inflammation of the lower genital tract, then tubal inflammation can lead to complications of ectopic pregnancy. ... In newborns can be infected from the mother through the placenta or after passing through the cervix, vagina of the infected mother, causing neonatal conjunctivitis.

Lymphogranulomatosis

This is the causative agent of venereal lymphadenitis in the groin or Nicolas Favre's disease caused by Chl.trachomatis serotypes L1, 2, 3. Sexually transmitted disease, after 3 - 26 days of exposure, the following symptoms appear: localized genital tract lesions manifest as a small ulcer on the glans, anus, vulva... The ulcer is transient then heals without scarring, after 1-2 months there are many inguinal lymph nodes, concentrated in a large mass and then protruded as an abscess, the mouth of the fistula is like a honeycomb or the mouth of a watering can. Inguinal lymphadenitis heals without scarring. However, the damage can cause complications: anal - rectal stenosis, elephant's foot, encephalitis - meningoencephalitis, joint pain... accompanied by systemic signs of fever and splenomegaly.

Parrot fever - bird fever (Psittacosis - Ornithosis)

 Disease caused by Chlamydia psittaci. Incubation 1-2 weeks, the disease is sudden or insidious. Chills, fever, headache, and atypical pneumonia. Pathogens are found in domesticated birds such as pigeons, chickens, ducks, parrots, and some wild birds. The disease is spread through the respiratory tract or through wounds. The bacteria enter the bloodstream and then reach the lungs, from where they are spread to others through the respiratory tract.

Treatment with tetracyclines. Sulfamides and streptomycin have no effect.

Disease caused by Chlamydia pneumonia

With interstitial pneumonia, bronchitis, sinusitis, pharyngitis are common in adolescents and young adults, in the elderly often manifest as benign and asymptomatic.

Microbiological diagnosis

Direct diagnosis

Because the bacteria are intracellular parasites, the specimen should be rich in epithelial cells such as:

Urethral curettage, prostate fluid, semen, intracervical fluid, tubal biopsy specimen, sacral fluid from the vagina.

Conjunctival curettage in trachoma.

Nasopharyngeal secretions, bronchopulmonary secretions, bronchial lavage fluid.

Specimens need to be stored at 40 ° C.

Microscopic staining of the specimens on the slides stained by the Jemsa or Machiavello method showed basophilic granules in or out of the cells. Chlamydia can be isolated on cell cultures or inoculated into incubated eggs to observe the infectivity. Determination by direct or indirect immunofluorescence to detect Chlamydia can use enzyme immunoassay (ELISA) to detect antigens of Chlamydia. It is now possible to use gene amplification (PCR techniques) to diagnose infections caused by Chlamydia trachomatis.

Indirect diagnosis

Micro-immunofluorescence is used to identify antibodies and allow the diagnosis of infectious species, particularly Chlamydia trachomatis.

In addition, complement combination reaction and ELISA reaction are also used to detect anti-lipopolysaccharide antibodies. However, the serum must be taken 2 times 2 weeks apart to find antibody titers.

Prevention and treatment

Prevent

For trachoma: it is necessary to strengthen hygiene measures such as not sharing towels, ensuring clean water in daily life...

For urogenital diseases that are easily spread by sex, it is necessary to detect them early and treat them promptly and take preventive measures for the husband or wife, eliminate prostitution, and educate them on sex.

Vaccine prevention is still being studied.

Treatment

Treatment with tetracycline, sulphonamide, erythromycin depending on each species of Chlamydia.