Phagocytosis and killing of epidemic methicillin-resistant Staphylococcus aureus by human neutrophils and monocytes

Staphylococcus aureus is a pathogen that has been associated with nosocomial infections since the preantibiotic era. Since the introduction of antibiotics in medical practice in the 1940 s, methicillin-resistant S. aureus (MRSA) strains have been emerging in various parts of the world. In view of the important role of the phagocytic system in the defense against this bacteria, we decided to study phagocytosis by neutrophils and monocytes of an epidemic MRSA strain in São Paulo, Brazil, in comparison with methicillin-sensitive strains. Complement system opsonins are fundamental for efficient ingestion of the resistant and sensitive strains by both types of phagocytes. We found no association of the opsonic requirement of the MRSA strain with the multiresistance phenotype. On the other hand, the MRSA strain was found to be more resistant to the effector mechanisms of neutrophils than both sensitive strains when opsonized with fresh serum, despite the phagocytosis results. This fact suggests that the intracellular killing of S. aureus is an additional parameter of bacterial virulence, but new approaches must be implemented to study the interactions of this MRSA strain with phagocytes in order to investigate the possible factors involved in its behavior in response to neutrophil effector mechanisms.Adolfo Lutz Institute Immunology SectionFederal University of São Paulo Department of Infectious and Parasitic DiseasesUNIFESP, Department of Infectious and Parasitic DiseasesSciEL

Assessment of oxidative metabolism

Oxidative metabolism is one of the central physiological processes that regulate multiple functions in a cell including cell death and survival, proliferation, gene transcription, and protein modification. There are multitudes of techniques that are used to evaluate oxidative activity. Here, we summarize how to measure oxidative activity by flow cytometry. This versatile technique allows the evaluation of the level of oxidative activity within heterogeneous populations of cells and in cell culture. Flow cytometry is a quick method that yields highly reproducible results with small sample volumes. Therefore, it is an ideal technique for evaluating changes in oxidative activity in samples from mice

Phagocytosis and killing of epidemic methicillin-resistant Staphylococcus aureus by human neutrophils and monocytes

Staphylococcus aureus is a pathogen that has been associated with nosocomial infections since the preantibiotic era. Since the introduction of antibiotics in medical practice in the 1940 s, methicillin-resistant S. aureus (MRSA) strains have been emerging in various parts of the world. In view of the important role of the phagocytic system in the defense against this bacteria, we decided to study phagocytosis by neutrophils and monocytes of an epidemic MRSA strain in São Paulo, Brazil, in comparison with methicillin-sensitive strains. Complement system opsonins are fundamental for efficient ingestion of the resistant and sensitive strains by both types of phagocytes. We found no association of the opsonic requirement of the MRSA strain with the multiresistance phenotype. On the other hand, the MRSA strain was found to be more resistant to the effector mechanisms of neutrophils than both sensitive strains when opsonized with fresh serum, despite the phagocytosis results. This fact suggests that the intracellular killing of S. aureus is an additional parameter of bacterial virulence, but new approaches must be implemented to study the interactions of this MRSA strain with phagocytes in order to investigate the possible factors involved in its behavior in response to neutrophil effector mechanisms

Desenvolvimento de dieta artificial para Cycloneda sanguinea (Coleoptera: Coccinellidae).

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