title: Phagocytosis and intracellular killing of rokitamycin-exposed staphylococci by human polymorphonuclear leukocytes.
abstract: The exposure of bacteria to antibiotics at even sub-minimum inhibitory concentrations (sub-MICs) induces physicochemical and biochemical modifications that facilitate phagocytosis and intracellular killing by polymorphonuclear leukocytes (PMNs). These PMN functions were investigated by exposing Staphylococcus aureus strains to different sub-MICs (1/2 to 1/32 MIC) of rokitamycin (RKM). Although phagocytosis and the index of phagocytosis of the antibiotic-exposed staphylococci were not significantly modified with respect to controls, the percentage of killing significantly increased after exposure to 1/2 and 1/4 MIC by 31 and 22%, respectively. Taking into consideration the other aspect of a possible direct interaction between RKM and PMNs, it was observed that up to 10 micrograms/ml of RKM did not interfere with phagocytosis but significantly enhanced killing activity by up to 33%. This effect can be correlated with the high uptake of RKM by PMNs (cellular/extracellular ratio congruent to 30.5). The relevance of these in vitro observations to clinical situations remains to be further investigated.
authors.affiliation: Department of Pharmacology, School of Medicine, University of Milan, Italy.
authors.forename: P C
authors.initials: PC
authors.lastname: Braga
authors.forename: M T
authors.initials: MT
authors.lastname: Sala
authors.forename: L
authors.initials: L
authors.lastname: Mancini
authors.forename: M
authors.initials: M
authors.lastname: Da Sasso
mesh_terms: D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D006801:Humans; D008856:Microscopy, Fluorescence; D015644:Miocamycin / Q000031:analogs & derivatives* / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000276:immunology*; D010587:Phagocytosis / Q000187:drug effects*; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D015644:Miocamycin; C033383:rokitamycin