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Cefonicid potentiation of human macrophage activity
V Tullio1, A M Cuffini, S Fazari
1Institute of Microbiology, University of Turin, Italy.
Abstract:
This study was undertaken to evaluate the in vitro effects of cefonicid on phagocyte functions such as phagocytosis and intracellular killing of phagocytosed bacteria. At concentrations of half the MIC cefonicid caused human macrophages to ingest and kill Klebsiella pneumoniae at a greater rate than did drug-free macrophages. Bacteria pretreated with subinhibitory concentrations of cefonicid became more susceptible to the phagocytic and bactericidal activity of macrophages than untreated microorganisms. Sub-MIC cefonicid pretreatment of macrophages did not reduce phagocytosis and killing, confirming the inability of beta-lactam antibiotics to cross biological membranes.
Insights
Cefonicid enhances macrophage ability to ingest and kill Klebsiella pneumoniae. This antibiotic boosts phagocyte functions, making bacteria more susceptible to immune defenses, even at sub-inhibitory concentrations.
Area of Science:
- Immunology
- Pharmacology
- Microbiology
Background:
- Phagocyte dysfunction can impair bacterial clearance.
- Understanding antibiotic effects on host immune cells is crucial for optimizing therapy.
- Beta-lactam antibiotics are known for their bactericidal activity but their impact on phagocyte function requires further investigation.
Purpose of the Study:
- To investigate the in vitro effects of cefonicid on human macrophage phagocytosis and intracellular killing of Klebsiella pneumoniae.
- To determine if sub-inhibitory concentrations of cefonicid modulate phagocyte activity.
- To assess the impact of cefonicid on bacterial susceptibility to phagocytosis.
Main Methods:
- In vitro assessment of human macrophage phagocytosis and intracellular killing.
- Exposure of Klebsiella pneumoniae and macrophages to cefonicid at various concentrations, including sub-MIC.
- Quantification of bacterial ingestion and killing by macrophages.
Main Results:
- Cefonicid, at half the minimum inhibitory concentration (MIC), significantly increased macrophage phagocytosis and intracellular killing of Klebsiella pneumoniae.
- Bacteria pretreated with sub-MIC cefonicid exhibited increased susceptibility to macrophage-mediated killing.
- Macrophage pretreatment with sub-MIC cefonicid did not impair phagocytosis or killing, suggesting limited antibiotic penetration into host cells.
Conclusions:
- Cefonicid demonstrates immunomodulatory effects, enhancing phagocyte functions against Klebsiella pneumoniae.
- Sub-inhibitory concentrations of cefonicid can potentiate the host's innate immune response.
- These findings highlight a dual mechanism of action for cefonicid: direct bactericidal activity and enhancement of phagocyte-mediated bacterial clearance.