Microbial hyaluronidase, coagulase, and streptokinase are examples of
Multiple Choice
exoenzymes.
hemolysins.
exotoxins.
antiphagocytic factors.
adhesive factors.
The correct answer and explanation is:
The correct answer is exoenzymes.
Explanation:
Microbial hyaluronidase, coagulase, and streptokinase are categorized as exoenzymes, which are enzymes secreted by microorganisms to perform specific extracellular functions. These enzymes play crucial roles in promoting microbial pathogenicity by breaking down host tissues, facilitating invasion, and evading the immune system.
- Hyaluronidase: Hyaluronidase breaks down hyaluronic acid, a major component of the extracellular matrix that holds cells together in connective tissue. By degrading this matrix, hyaluronidase creates spaces in tissues, allowing pathogens to penetrate deeper into the host. This “spreading factor” enables the bacteria to invade and establish infections in previously inaccessible sites.
- Coagulase: Coagulase is an enzyme that facilitates the conversion of fibrinogen to fibrin, leading to the formation of blood clots. Certain bacteria, such as Staphylococcus aureus, use coagulase to create a protective fibrin barrier around themselves. This helps them evade phagocytosis and other host immune responses, thus promoting survival within the host.
- Streptokinase: Streptokinase works by activating plasminogen, a precursor to plasmin, which is an enzyme that dissolves fibrin clots. Bacteria such as Streptococcus pyogenes use streptokinase to break down clots, facilitating their spread through host tissues and ensuring a wider dissemination of infection.
Why Exoenzymes?
Exoenzymes are secreted extracellularly and act outside the microbial cell, unlike other factors like exotoxins (which are toxic proteins) or antiphagocytic factors (which prevent phagocytosis by immune cells). Exoenzymes specifically target host structures like connective tissue or blood clots to enhance microbial survival and invasion, making them key virulence factors.
In contrast, hemolysins lyse red blood cells, exotoxins are toxins secreted to damage host cells, and adhesive factors help pathogens adhere to host tissues, all of which serve different functions in pathogenesis. Thus, hyaluronidase, coagulase, and streptokinase are clearly exoenzymes.