Question

Which infection in diabetes causes the most morbidity and why?

Answer 1

Diabetic patients are more prone to bacterial infection. Common sites of infection are skin, foot, kidneys, bladder etc.

1)In normal persons, bacterial infection results in the release of cytokines, which attract the neutrophils and monocytes to the site of infection. This process is called chemotaxis. a variety of molecules are expressed on the surface of endothelial cell surface ,which help the neutrophils and monocytes to adhere to the surface. Once they are adhered they migrate into the subendothelial tissue to reach the site of infection. Here the monocytes transforms into macrophages. Neutrophils and the macrophages then eliminate the bacteria by the process of phagocytosis.

But in a diabetic patient, hyperglycemia condition prevent the  adherence of these immune cells on the surface of endothelial cell. More over the the migrated macrophages are prevented from reaching the site of infection for phagocytosis, resulting in bacterial infection.

2) In normal persons, another immune mechanism called the compliment cascade system get activated by bacterial infection. This cascade system results inthe formation of trans membranre protein on bacterial cell surface called MAC (membrane attack complex). This MAC formation makes the bacterial membrane porous and rapid influx of fluid into the bacterial cell makes the organism to die.

But hyperglycemia condition inhibits the proper activation of this compliment cascade system and thus block another pathway of immune system, ther by causing bacterial infection to the diabetic patient.