Prophylactic administration of antibiotics compromises reticuloendothelial system function and exacerbates shock mortality in rats.

The effects of short-term (3 days) administration of three different antimicrobial agents (i.e., kanamycin, cephalothin and polymyxin B) on reticuloendothelial system (RES) phagocytic function and mortality after bowel ischaemic shock was studied in intact rats. All three antibiotics significantly depressed RES phagocytic function and exacerbated mortality after shock. The degree of antibiotic-induced inhibition of RES function seemed to parallel the antimicrobial effects on shock mortality; the greater the degree of RES inhibition, the greater the degree of exacerbation of shock mortality. In view of such findings, caution should be exercised in administering antibiotics prophylactically to patients and animals.