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 equals 0.88) but no correlation between staphylococcal superoxide dismutase activity and mouse lethality (r equals 0.14). Exogenous catalase (10,000 U/ml) increased the virulence of low-catalase staphylococci, but exogenous superoxide dismutase (200 mug/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 strain. Addition of exogenous catalase decreased iodination of the low-catalase strain by 23%. These findings suggest that staphylococcal catalase protects intraphagocytic microbes by destroying hydrogen peroxide produced by the phagocyte. Thus, catalase may be a significant staphylococcal virulence factor.
G L Mandell
Usage data is cumulative from April 2023 through April 2024.
Usage | JCI | PMC |
---|---|---|
Text version | 581 | 0 |
123 | 89 | |
Scanned page | 89 | 24 |
Citation downloads | 15 | 0 |
Totals | 808 | 113 |
Total Views | 921 |
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.