Effect of abnormal levels of serum components on antibiotic activity

Abstract

Antibiotic activity in serum from a model for type II diabetes was similar to that in normal sera or media containing cholesterol but lacking glucose, insulin, or both. The ratio of effects of broth plus obese-rat serum to effects of broth plus lean-rat serum supplemented with cholesterol approached or equaled 1.The interactions of antibiotics with serum components, including serum proteins and cholesterol, have been demonstrated to be important determinants of their activity in serum. It has been well documented that the levels and types of proteins found in serum can profoundly affect antibiotic activity, especially that of penicillin and others of the 1-lactam class (1,2). Another serum component, cholesterol, which is commonly elevated in persons in Western society, can act as a competitive inhibitor for members of the polyene class of antibiotics, such as amphotericin B (6, 11). Obesity is often associated with changes in the levels of serum components. In obesity-associated type II diabetes, both serum insulin and glucose can be elevated. Altered levels of cholesterol, triglycerides, free fatty acids, and lipoproteins are also commonly associated with obesity and type II diabetes (3,10,13,14). The effect that these skewed levels of serum components have on antibiotic activity is not known.In this study, we