What are the virulence factors of Mycobacterium tuberculosis?
What are the virulence factors of Mycobacterium tuberculosis?
In the present review, the virulence determinants have been divided into the following categories based on their function, molecular features or cellular localization: (1) Lipid and fatty acid metabolism, including catabolism of cholesterol, (2) cell envelope proteins: including cell wall proteins, lipoproteins and …
Is Mycobacterium tuberculosis catalase positive or negative?
tuberculosis and other tubercle bacilli. Catalase converts hydrogen peroxide to water and oxygen, generating oxygen bubbles in a liquid solution. Virtually all mycobacteria except certain isoniazid-resistant tubercle bacilli are catalase-positive.
Is TB catalase positive?
Semiquantitative catalase test is used for the identification of Mycobacterium tuberculosis. It is used to differentiate aerotolerant strains of Clostridium, which are catalase negative, from Bacillus species, which are positive.
What is mycobacterial catalase-peroxidase?
tuberculosis catalase-peroxidase (KatG), the enzyme responsible for activation of the antituberculosis antibiotic isoniazid (isonicotinic acid hydrazide), have confirmed that the heme iron in the resting (ferric) enzyme is high-spin five-coordinate.
What are examples of virulence factors?
Factors that are produced by a microorganism and evoke disease are called virulence factors. Examples are toxins, surface coats that inhibit phagocytosis, and surface receptors that bind to host cells.
Where can Mycobacterium tuberculosis be found?
Tuberculosis (TB) is an acute or chronic bacterial infection found most commonly in the lungs. The infection is spread like a cold, mainly through airborne droplets breathed into the air by a person infected with TB. The bacteria causes formation of small tissue masses called tubercles.
What type of bacteria are catalase negative?
If no bubbles appear, the bacteria are catalase negative. Staphylococcus and Micrococcus spp. are catalase positive, whereas Streptococcus and Enterococcus spp. are catalase negative.
What does positive catalase test mean?
The catalase test tests for the presence of catalase, an enzyme that breaks down the harmful substance hydrogen peroxide into water and oxygen. Bubbles are a positive result for the presence of catalase. If no bubbles form, it is a negative result; this suggests that the organism does not produce catalase.
What is the aim of catalase test?
The catalase test is used to differentiate staphylococci (catalase-positive) from streptococci (catalase-negative). The enzyme, catalase, is produced by bacteria that respire using oxygen, and protects them from the toxic by-products of oxygen metabolism.
What are catalase positive organisms?
Staphylococci and Micrococci are catalase-positive. Other catalase-positive organisms include Listeria, Corynebacterium diphtheriae, Burkholderia cepacia, Nocardia, the family Enterobacteriaceae (Citrobacter, E.