Conditions Predisposing to Infection

A. Diabetes

A variety of factors contribute to the increased risk of infection in diabetics.

Subtle host defense abnormalities such as glycosylation of immunoglobulins and C3, delayed inflammatory response and decreased neutrophil function have all been demonstrated in diabetics and linked to poor glycemic control.

It is felt that these defects make diabetics more prone to infections with Staph. aureus, enteric gram negatives, Pseudomonas and certain fungi.

However, correlation of these findings with an increased risk of in vivo infection has been difficult to demonstrate.

The most important factor seems to be these patient’s general debility and presence or absence of such complications as vascular compromise and neuropathy.

Diabetics are more susceptible to rhinocerebral mucor and malignant otitis externa (Pseudomonas).Other serious infections such as influenzal pneumonia, staph and gram negative bacteremia may be more severe secondary to general debility and metabolic complications.

B. Uremia

Uremic toxins appear to be responsible for delayed chemotaxis, attenuated antibody response to vaccines, impaired interferon production and decreased clearance of opsonized particles by the spleen.

Need for vascular or peritoneal access provides a portal of entry for the microorganisms.

Nutritional deficiencies (see below) impair host defense as well.

All of these factors combine to make renal patients prone to wide array of infections.

C. Hemolysis

Chronic hemolysis leads to pigment overload of the RES and to a decrease in monocyte-macrophage function.

This has best been studied in sickle cell patients but is seen in all forms of chronic hemolysis.

Depression of the RES markedly predisposes to Salmonella bacteremia and metastatic infection and possibly to infection with other intracellular parasites.

D. Malnutrition

Protein-calorie malnutrition is commonplace among medical and surgical inpatients.

These patients are generally suffering from other factors leading to an immunocompromised state (neoplasms, extensive surgical disease, etc.).

Malnutrition has adverse effects on skin and mucous membrane integrity, phagocytic cell function, cell-mediated immunity, primary antibody responses and function of both complement pathways. All efforts should be made to correct malnutrition before acute infection develops as it is extremely difficult to correct afterwards.