ABSTRACT

The objective of this study was to investigate the effect of antimicrobial cationic peptide nisin (32µg/mL) at minimal inhibitory concentration (MIC) alone in combination with amikacin (21µg/mL), ceftazidime (42µg/mL) and imipenem (50µg/mL) at therapeutic concentrations and their combinations with nisin on polymorphonuclear leukocyte (PMN) functions (phagocytosis and intracellular killing activity) were examined in vitro on 20 healthy volunteers whose mean age was 25. PMNs (1x107 cells/mL) were isolated by ficoll-hypaque gradient centrifugation method from venous blood with ethylene diaminetetraacetic acid (EDTA). Phagocytosis and intracellular killing activity were assayed by modifying Alexander’s method. It was observed that nisin, nisin+amikacin, nisin+ceftazidime and nisin+imipenem combinations significantly decreased phagocytosis and intracellular killing activity of PMNs in healthy volunteers when compared with the control (p <0.001). Consequently, while nisin alone and in combination with amikacin, ceftazidime, and imipenem showed inhibitory activity on PMN functions, amikacin, ceftazidime and imipenem at therapeutic concentraions does not impair normal PMN function.The finding of our study shows the importance of PMN functions for its potential influence in decision of rational antimicrobial selection is extremely important for success of therapy. Additional studies are necessary to elucidate the nature of these immunologic phenomenon.