What are the Biotypes of Corynebacterium Diphtheriae?

Corynebacterium diphtheriae is a type of bacteria that can cause diphtheria, a serious and potentially life-threatening infection. Corynebacterium diphtheriae is classified into three biotypes that are gravis, intermedius, and mitis based on its ability to produce certain toxins and enzymes;

Diphtheria is primarily spread through close contact with an infected person, usually through respiratory secretions such as saliva or mucus. The bacteria produce a toxin that can damage the heart, nerves, and other organs.

Diphtheria can be treated with antibiotics, but it is important to seek medical attention as soon as possible to prevent serious complications. Vaccines are also available that can help protect against diphtheria and other diseases caused by Corynebacterium bacteria.

biotype of corynebacterium diptheriae

Corynebacterium diphtheriae is a gram-positive, rod-shaped bacterium that is typically found in the respiratory tract of humans and animals. It is a member of the Corynebacterium genus, which includes a number of species that are commonly found in the environment and on the skin and mucous membranes of humans and animals.

C. diphtheriae is further classified into different biotypes based on its ability to produce certain toxins and enzymes. The most common biotypes of C. diphtheriae are gravis, intermedius, and mitis.

C. diphtheriae biotype gravis is the most virulent and is responsible for most cases of diphtheria. It produces a potent toxin that can damage the heart, nerves, and other organs.

C. diphtheriae biotype intermedius is less virulent than gravis and is less common. It can cause infections similar to those caused by biotype gravis, but the symptoms are generally milder.

C. diphtheriae biotype mitis is the least virulent of the three biotypes and is not known to cause disease in humans. It is often found in the respiratory tract of healthy individuals and is not generally considered a pathogen.

What are the Biotypes of Corynebacterium Diphtheriae?

McLeod and Anderson classified diphtheria bacilli, based on the colony characteristics of the Tellurite medium and other properties like biochemical reactions and severity of the disease.

PropertiesGravisIntermediusMitis
Morphology– Short Rods
– Uniform Staining
– Few or no granules
– Maybe pleomorphic
– Long-barred forms, clubbed end
– Poor Granulation
– Very pleomorphic
– Long Rods
– curved shaped
– pleomorphic
– Prominent granules
Colony on Tellurite Blood Agar≥ 2mm, dull greyish black, opaque colonies, daisy head, brittle, like cold margarine.< 0.5 mm, gray colony, dark center shining surface, frog’s egg colonies≥ 2mm, gray, opaque glossy, smooth surface, poached egg colonies, soft buttery, easily emulsifiable
HemolysisVariableNon-hemolyticUsually Hemolytic
Glycogen and Starch fermentationPositiveNegativeNegative
Antigen Types13440
Fatality RateHighHighLow
ComplicationsParalyticHemorrhagicObstructive
EndemicityEpidemicEpidemicEndemic

What is the Fatality Rate of Corynebacterium diphtheriae?

Corynebacterium diphtheriae is a bacterium that can cause a serious and potentially life-threatening infection called diphtheria.

The fatality rate of diphtheria varies depending on a number of factors, including the age and overall health of the infected person, the severity of the infection, and the timely administration of appropriate treatment.

According to the World Health Organization (WHO), the global fatality rate for diphtheria is approximately 5-10%. However, the fatality rate can be much higher in certain populations, such as children under 5 years of age, older adults, and individuals with underlying health conditions. In these groups, the fatality rate can be as high as 20-30%.

It is important to seek medical attention as soon as possible if you or someone you know is experiencing symptoms of diphtheria, such as a thick,

  • gray or white coating on the throat,
  • difficulty swallowing,
  • fever,
  • weakness,
  • swollen neck glands

Diphtheria can be treated with antibiotics, but it is important to start treatment as soon as possible to prevent serious complications. Vaccines are also available that can help protect against diphtheria and other diseases caused by Corynebacterium bacteria.

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