Influence of subinhibitory concentrations of Clindamycin on the phagocytosis of Staphylococcus aureus

Abstract

The process of phagocytosis by Polymorphonuclear leukocytes (PMN) and monocytes (MN), the major host defense mechanism against invading microorganisms, has been shown to be influenced by various antibiotics [1]. One way of interaction between antibiotics and phagocytic cells is that phagocytes may react differently with bacteria when the bacterial surface has been altered by antibiotics. It has been shown that exposure to some antibiotics at concentrations lower than the minimal inhibitory concentration (MIC), not only induce morphological changes in certain bacteria [7], but also a higher susceptibility of these bacteria to phagocytosis [2, 3,4,8,9]. As opsonization of S. aureus is necessary for phagocytosis it may be possible that the enhanced uptake by phagocytes of these antibiotic treated bacteria that was observed takes place due to enhanced opsonization [2,5]. Because opsonization is determined by the binding of antibodies and C3b to the bacterial surface, the enhanced uptake of microorganisms by PMN after exposure to subinhibitory concentrations of antibiotics may be due to changes in the structure of antibody binding or complement activating sites.