cytochalasin-d and Staphylococcal-Infections

We hypothesized that if internalization of Staphylococcus aureus could be blocked by using cytochalasin D (an inhibitor of phagocytosis and phagolysosome fusion), then the intracellular entry and survival of the pathogen in host's phagocytic cells recruited to the inflammatory site can be restricted. At the same time, if we use antimicrobial agents (e.g., ciprofloxacin and azithromycin) having potent intracellular and extracellular microbicidal activity against the bacterium that have not entered into the phagosome and remains adhered to the phagocytic cell membrane, then they can be eradicated from the site of infection without compromising the host cell. To validate this, role of ciprofloxacin (CIP) and azithromycin (AZM) in eliminating S. aureus by suppressing the phagocytic activity of macrophages with cytochalasin D before infection was investigated. CIP and AZM were used either alone or in combination with cytochalasin D. Supernatant and lysate obtained from the culture of macrophages were used for quantification of reactive oxygen species, lysozymes, antioxidant enzymes, and cytokines produced. Azithromycin was better than ciprofloxacin in combination with cytochalasin D for eradicating S. aureus and regulating cytokine release. Further studies are required for ensuring proper delivery of this combination at the site of infection.

Topics: Animals; Anti-Bacterial Agents; Anti-Inflammatory Agents; Antioxidants; Azithromycin; Ciprofloxacin; Cytochalasin D; Drug Therapy, Combination; Glutathione; Hydrogen Peroxide; Inflammation; Interferon-gamma; Interleukin-10; Interleukin-6; Macrophages; Male; Mice; Microbial Sensitivity Tests; Muramidase; Phagocytosis; Staphylococcal Infections; Staphylococcus aureus; Superoxide Dismutase; Tumor Necrosis Factor-alpha

Staphylococcus aureus is one of the most important pathogens of the bovine mammary gland. The interaction of S. aureus with cells of the bovine mammary gland is considered to play an essential role in the pathogenesis. In this study, we identified a new target cell for S. aureus adhesion and invasion. For that purpose, cells which compose the alveoli of the mammary gland were cultured. In these cultures, two morphologically different cell types, elongated and cubic cells, were observed. Adhesion and invasion of S. aureus was studied using microscopical and microbiological methods. S. aureus adhered specifically and in large numbers (about 300 bacteria/cell) to the elongated cell type. No adhesion to the cubic cell type was observed. In addition, bacteria were also found intracellularly in the elongated cells, and enclosed in membrane vesicles. Adhesion and invasion were time dependent and reached maximum levels after 4 h. Invasion was strongly reduced by staurosporine and genistein. The newly identified target cell was further characterized.

Topics: Animals; Antibodies, Monoclonal; Bacterial Adhesion; Cattle; Cell Culture Techniques; Colchicine; Cytochalasin D; Enzyme Inhibitors; Female; Immunohistochemistry; Lactation; Mammary Glands, Animal; Mastitis, Bovine; Microscopy, Electron; Nucleic Acid Synthesis Inhibitors; Staphylococcal Infections; Staphylococcus aureus; Staurosporine; Tropism