Question

How might a bacterium resist thekilling effects of a phagolysosome?

Answer 1

Answer: Through the inhibition of the fusion between the phagosome and the lysosome.

Step-by-step explanation:

Bacteria are pathogens recognized by the immune system. When one of them enters the body, cells of the innate immune system such as dendritic cells or macrophages recognize them and phagocyte them. These bacteria, once inside the immune system cell (called phagocyte), are housed in vesicles called phagosomes. They eventually fuse with lysosomes, which are organelles containing hydrolytic enzymes for the degradation of componentens. When the phagosome, which contains the bacteria, fuses with the lysosome, the bacteria are degraded.

The bacteria may be able to survive inside of phagosomes because they prevent the fusion of the phagosome with the lysosome. And this prevents the discharge of lysosomal enzymes into the phagosome.

This strategy is employed, for example, by M. tuberculosis and Salmonella. This can be achieved through the release of sulfates which are bacterial cell wall components. Those sulfates modify the lysosomal membrane and this inhibits the fusion.

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Answer 2

There are several mechanisms, like resistance to antimicrobial agents, encapsulation or secretation of proteins that affects and might destroy the phagocyte

Step-by-step explanation:

Some leukocytes in our body perform phagocytosis as a defense mechanism against the pathogenic bacterium. These phagocytes contain lysosomes, intracellular granules that possess bactericidal substances (especially toxic oxygen species, such as H2O2) and enzymes (proteases, lipases, etc.). When the phagocyte ingests the pathogen, a phagosome is formed, which merges with the lysosome, forming the phagolysosome, which is where toxic substances and enzymes kill the ingested microorganism.

There are several mechanisms by which a microorganism can survive this process:

-Resistance to antimicrobial agents. Some bacteria use phenolic glycolipids from their cell wall, to eliminate toxic oxygen compounds (i.e Staphylococcus aureus and mycobacterium tuberculosis).

-Some pathogens produce a protein called leukocidin, a cytotoxin that destroys the phagocyte and the pathogen is free. Generally, these bacteria are the generators of pus, like Streptococcus pyogenes.

- There are bacteria whose mechanism is encapsulation, increasing their resistance to phagocytosis (i.e Streptococcus pneumoniae). Some even secrete substances on their surfaces, called M proteins, that prevents phagocytosis from completing