What is the pathogenesis of Corynebacterium diphtheriae?
The pathogenesis of diphtheria is based upon two primary determinants: (1) the ability of a given strain of C diphtheriae to colonize in the nasopharyngeal cavity and/or on the skin, and (2) its ability to produce diphtheria toxin.
What is the mechanism of pathogenicity for diphtheria?
Diphtheria toxin is an exotoxin secreted by Corynebacterium, the pathogenic bacterium that causes diphtheria. The toxin gene is encoded by a prophage called corynephage β. The toxin causes the disease in humans by gaining entry into the cell cytoplasm and inhibiting protein synthesis.
How does Corynebacterium diphtheriae affect the body?
Diphtheria is a serious infection caused by strains of bacteria called Corynebacterium diphtheriae that make toxin (poison). It can lead to difficulty breathing, heart failure, paralysis, and even death.
Does Corynebacterium diphtheriae invade the bloodstream?
The toxin produced at the site of the membrane is absorbed into the bloodstream and then distributed to the tissues of the body. The toxin is responsible for major complications such as myocarditis, polyneuropathies, and nephritis, and can also cause thrombocytopenia.
What is the arrangement of Corynebacterium diphtheriae?
Corynebacterium diphtheriae, the causative agent of diphtheria, is known to have a morphologically unique structure, a club shape of the cell, from which the name of this genus was derived. V, W, X, and Y-shapes or a palisade arrangement of the cells are also characteristics morphological feature of this species (5).
What is the morphology of Corynebacterium diphtheriae?
C. diphtheriae is a pleomorphic, club-shaped, Gram positive bacillus that is catalase positive, non-motile, non-spore forming, and non-acid fast. On Gram stain, the organisms are typically described as having a “picket fence” or “Chinese character” morphology (image 3).
What is the arrangement of Corynebacterium Diphtheriae?
What is the characteristic toxin produced by Corynebacterium Diphtheriae?
Corynebacterium diphtheriae is an aerobic gram-positive bacterium which secretes a toxin that inactivates human elongation factor eEF-2, thus inhibiting translation during protein synthesis by human cells.
What are the complications of diphtheria?
Complications from respiratory diphtheria (when the bacteria infect parts of the body involved in breathing) may include:
- Airway blockage.
- Damage to the heart muscle (myocarditis)
- Nerve damage (polyneuropathy)
- Loss of the ability to move (paralysis)
- Kidney failure.
Which body system does diphtheria affect?
Diphtheria can infect the respiratory tract (parts of the body involved in breathing) and skin.
What is the major virulence factor associated with Corynebacterium diphtheriae?
The main virulence factor of C. diphtheriae is diphtheria toxin (DT), an exotoxin, released by the bacteria after entering the human body.
Is Corynebacterium diphtheriae beta hemolytic?
CORYNEBACTERIA – CULTIVATION ON BLOOD AGAR on media with blood with a weak beta-hemolysis (C. diphtheriae biotype mitis and gravis) or is nonhemolytic (biotype intermedius).
How does corynebacterium diphtheria cause severe disease?
Corynebacterium diphtheria. C. diphtheriae is an aerobic gram-positive bacillus. Toxin production (toxigenicity) occurs only when the bacillus is itself infected (lysogenized) by a specific virus (bacteriophage) carrying the genetic information for the toxin (tox gene). Only toxigenic strains can cause severe disease.
Is the pathogenesis of c.diphtheriae an invasive organism?
C. diphtheriae is not an invasive organism. The pathogenesis of diphtheria is based on its potent exotoxin carried by lysogenized strains of C. diphtheriae. Like other exotoxins (botulinum, tetanus, cholera toxin), diphtheria toxin also has A and B subunits.
What does Corynebacterium diphtheriae look like in Albert stain?
C. diphtheriae appears as green bacilli with bluish-black metachromatic granules in Albert stain. Corynebacterium diphtheriae is a fastidious organism, so it does not grow on the ordinary medium. To avoid the growth of commensals and to differentiate among various biotypes, the sample should be cultured
Why is cutaneous diphtheria common in the tropics?
Cutaneous diphtheria is quite common in the tropics and is probably responsible for the high levels of natural immunity found in these populations. Infection with toxigenic strains appears to result less frequently in systemic complications with cutaneous compared to other forms of diphtheria.