No abstract

No abstract

A B S T R A C T Since oxygen-free polymorphonuclear neutrophils (PMN) cannot kill Staphylococcus aureus normally, the usual mechanisms for PMN bactericidal activity probably involve hydrogen peroxide or superoxide. Catalase can destroy hydrogen peroxide, and superoxide dismutase breaks down superoxide. Experiments were performed to study the influence of these enzymes (which are found in staphylococci) on virulence for mice or on leukocyte-bacterial interaction. 15 staphylococcal strains were injected i.p. into mice to quantitate virulence. There was good correlation between staphylococcal catalase activity and mouse lethality (r = 0.88) but no correlation between staphylococcal superoxide dismutase activity and mouse lethality (r = 0.14). Exogenous catalase (10,000 U/ml) increased the virulence of low-catalase staphylococci, but exogenous superoxide dismutase (200 izg/ml) did not alter the virulence of staphyloccal strains. C14-labeled high-catalase or low-catalase staphylococci were ingested equally well by PMN, with or without the addition of exogenous catalase. A high-catalase staphylococcal strain was killed relatively poorly by PMN, and addition of exogenous catalase (but not superoxide dismutase) decreased the ability of PMN to kill a low-catalase strain. Iodination of bacterial proteins by PMN is related to hydrogen peroxide, and a high-catalase staphylococcal strain was iodinated only 63% as much as a low-catalase Portions of this work were presented at the National

A B S T R A C T Bacteria that survive inside polymorphonuclear neutrophils (PMN) following phagocytosis are protected from the bactericidal action of most antibiotics. Two possible explanations are altered metabolism by intraleukocytic bacteria or failure of antibiotics to enter the phagosome. The oxygen consumption of intraleukocytic and extraleukocytic bacteria was measured as an index of bacterial metabolism. PMN respiration and bactericidal activity were suppressed with large doses of hydrocortisone and extraleukocytic bacterial oxygen consumption was abolished by the addition of lysostaphin. Intraleukocytic bacterial continued to consume oxygen suggesting that surviving ingested microorganisms are metabolically active. Neither penicillin (which cannot kill intraleukocytic bacteria) nor rifampin (which can kill intraleukocytic bacteria) was bactericidal for staphylococci at 5°C. Thus, rifampin is not uniquely able to kill "resting" bacteria. The total water space in the pellets was quantitated using tritium water and the extracellular water space was measured using Na2'5SO4. All penicillin associated with the cell pellet could be accounted for in extracellular water. Thus penicillin was completely excluded from the leukocytes. Rifampin was concentrated in the cell pellet 2.2 times when compared with the supernatant concentration.These studies suggest that a likely explanation for the survival of phagocytized bacteria in the presence of high concentrations of most antibiotics is the inability of the Dr. Mandell is the holder of a Research Career Development Award GM-49520 from the National Institute of General Medical Sciences.

No abstract