CORYNEBACTERIUM DIPHTHERIAE

CORYNEBACTERIUM DIPHTHERIAE

Morphology

• Corynebacterium diphtheriae is a gram-positive, non-motile, non-sporing rod.
• It is a pleomorphic organism with a characteristic club or boat-shaped appearance.
• The bacteria may appear in singles or in chains.
• The size of the bacteria is 0.5-1.5 microns in length and 0.5-1.0 microns in width.

Pathogenicity

• Corynebacterium diphtheriae produces diphtheria toxin (DT) which is responsible for the disease.
• The toxin is a potent exotoxin consisting of two chains, A and B.
• Chain A is responsible for the toxic activity and chain B serves as a receptor for the toxin.
• The toxin inhibits protein synthesis by cleaving the elongation factor 2 (EF-2).

Pathogenesis

• Corynebacterium diphtheriae enters the body through cuts or abrasions in the skin or through mucous membranes.
• The bacteria multiply in the tissues and produce diphtheria toxin.
• The toxin travels to the lymph nodes where it is produced in large quantities.
• The toxin is then released into the bloodstream where it travels to other parts of the body.
• The toxin causes necrosis of the cells and tissues, leading to the characteristic lesions.

Clinical Features

• The initial symptoms of diphtheria include sore throat, fever, and swollen lymph nodes.
• The bacteria produce a thick, grayish-white membrane on the tonsils and throat.
• The membrane is rich in diphtheria toxin and causes severe inflammation and tissue damage.
• The disease can lead to respiratory failure, heart failure, and paralysis.

Complications

• Diphtheria can lead to respiratory failure due to the blockage of the airways by the membrane.
• The toxin can cause cardiac arrhythmias and heart failure.
• Paralysis is a common complication of diphtheria.
• The disease can also lead to renal failure and neurological complications.

Laboratory Diagnosis

• Diphtheria can be diagnosed by culture of the bacteria from the throat or other infected tissues.
• The bacteria can be identified by their characteristic morphology and gram stain.
• The presence of diphtheria toxin can be detected by an ELISA test.
• PCR can be used to detect the toxin gene in the bacteria.

Treatment

• The treatment of diphtheria involves the administration of antitoxin to neutralize the toxin.
• Antibiotics such as erythromycin and penicillin are used to treat the infection.
• Supportive care is also necessary to manage the complications of the disease.

Memory Trick

• "Corynebacterium diphtheriae" can be remembered as "Cory" the bacteria, "Dip" the disease, "htheria" the toxin, and "EIA" the ELISA test.
• The pathogenesis of the disease can be remembered as "CUT" (Cuts or abrasions), "MUL" (Multiply in tissues), "TOX" (Toxin production), "LYM" (Lymph nodes), "BLO" (Bloodstream), and "CIT" (Cells and tissues).

Word Trick

• The word "Corynebacterium" can be remembered as "Cory" (Club-shaped) + "Bacterium" (Bacteria).
• The word "Diphtheria" can be remembered as "Dip" (Disease) + "heria" (Toxin).