title: Resistance of Nocardia asteroides to oxygen-dependent killing by neutrophils.
abstract: Nocardia asteroides resists killing by neutrophils despite the occurrence of the oxidative metabolic burst when the organism is phagocytosed. In a study of the apparent resistance of N asteroides to oxygen-dependent killing by neutrophils, this organism and (for comparison) Staphylococcus aureus were exposed to metabolites of the oxidative metabolic burst. N asteroides was more resistant than S aureus to H2O2, hydroxyl radical, and singlet oxygen and to the combination of H2O2, lactoperoxidase, and iodide. The rate of iodination of N asteroides by neutrophils or by the combination of lactoperoxidase and H2O2 was significantly lower than that of S aureus. Lysates of N asteroides had 2.8 times more catalase than lysates of S aureus, but levels of superoxide dismutase were similar in the two lysates. A reduction in the level of catalase activity of N asteroides with aminotriazole or azide resulted in a modest decrease in resistance to oxidative metabolites. Thus, the relative resistance of N asteroides to killing appeared to be due partially but not completely to its relatively high level of catalase activity.
mesh_terms: D002374:Catalase / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D009504:Neutrophils / Q000378:metabolism; D009616:Nocardia asteroides / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000502:physiology*; D013211:Staphylococcus aureus / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism*; D015054:Zymosan / Q000378:metabolism*
chemical_list: D015054:Zymosan; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D010100:Oxygen