Adhesion and phagocytosis of Staphylococcus aureus L-forms

Area of Science:

• Microbiology
• Immunology
• Cell Biology

Background:

• Staphylococcus aureus is a common pathogen.
• Macrophages are key immune cells that phagocytose and destroy bacteria.
• Bacterial cell wall integrity is crucial for host-pathogen interactions.

Purpose of the Study:

• To investigate the interaction between Staphylococcus aureus and rat peritoneal macrophages.
• To compare the fate of normal Staphylococcus aureus cells versus cell wall-deficient L-forms within macrophages.
• To assess the potential for intracellular survival of Staphylococcus aureus L-forms.

Main Methods:

• Electron microscopy was used to examine bacterial-macrophage interactions in vitro and in vivo.
• Normal Staphylococcus aureus and oxacillin-induced L-forms were incubated with rat peritoneal macrophages.
• L-forms were administered intraperitoneally to rats, and their persistence in macrophages was monitored.

Main Results:

• Normal Staphylococcus aureus cells were rapidly endocytosed and digested by macrophages.
• Staphylococcus aureus L-forms were ingested by macrophages but lacked phagolysosome formation.
• Intracellular L-forms retained their ultrastructure, showing no visible alterations.
• L-forms persisted within macrophages for up to 7 days after administration.

Conclusions:

• Staphylococcus aureus L-forms exhibit distinct intracellular behavior compared to parental strains.
• The absence of phagolysosome formation and degradation suggests a mechanism for L-form survival within macrophages.
• These findings indicate the potential for intracellular persistence of Staphylococcus aureus L-forms, which may have implications for chronic infections.