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Published on: February 16, 2022
Effect of nitric oxide on staphylococcal killing and interactive effect with superoxide
S S Kaplan1, J R Lancaster, R E Basford
1Department of Pathology, University of Pittsburgh School of Medicine, Pennsylvania 15213, USA.
Infection and Immunity
|January 1, 1996
Summary
Reactive nitrogen intermediates (RNI) like nitric oxide (.NO) cause delayed staphylococcal death, while reactive oxidative intermediates (ROI) like superoxide (O2-) kill rapidly. Their combined effect shows no early synergy but suggests .NO aids host defense.
Area of Science:
- Microbiology
- Immunology
- Biochemistry
Background:
- The role of reactive nitrogen intermediates (RNI), such as nitric oxide (.NO), in host defense against pyogenic microorganisms remains unclear.
- The interactive effects of RNI and reactive oxidative intermediates (ROI) on microbial killing are not well-defined, despite their potential co-occurrence during infection.
Purpose of the Study:
- To evaluate the separate and interactive effects of .NO and superoxide (O2-) on staphylococcal survival.
- To elucidate the mechanisms underlying RNI- and ROI-mediated microbial killing.
Main Methods:
- Utilized a simplified cell-free system to study staphylococcal survival under exposure to .NO and O2-.
- Assessed the impact of hemoglobin on .NO-mediated killing to confirm RNI involvement.
- Quantified bacterial viability over time following exposure to varying concentrations of .NO and O2-.
Main Results:
- .NO exposure resulted in a dose-related, delayed loss of staphylococcal viability, abrogated by hemoglobin.
- Superoxide (O2-) mediated rapid killing of staphylococci within 2 hours, which was dose-dependent.
- The interaction of .NO and O2- led to decreased O2--mediated killing at early time points, but .NO appeared to enhance killing over prolonged periods.
Conclusions:
- No early synergistic killing effect was observed between RNI and ROI.
- .NO may contribute to host defense, particularly when ROI-mediated killing is impaired, by providing delayed or stabilized microbial killing.
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