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Updated: Oct 8, 2026

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages
Published on: October 25, 2017
Phagocytosis and intracellular killing of rokitamycin-exposed staphylococci by human polymorphonuclear leukocytes
P C Braga1, M T Sala, L Mancini
1Department of Pharmacology, School of Medicine, University of Milan, Italy.
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.
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