Decrease in surface charge density of Klebsiella pneumoniae treated with cefodizime and enhancement of the phagocytic...

Treatment of Klebsiella pneumoniae 109 with cefodizime, ceftazidime, cefbuperazone, cefotaxime or flomoxef at a sub-minimum inhibitory concentration (sub-MIC) (1/4 MIC) for 1 h altered its morphology. The bacteria treated with cefodizime at sub-MICs (1/8, 1/4 MIC) enhanced the chemiluminescencence (CL) of human polymorphonuclear leucocytes (PMNs), implying an increase in the production of active oxygen species in association with phagocytosis, whereas the cells treated with other cephalosporins at the same sub-MICs did not. Furthermore, a significant decrease in electrophoretic mobility was induced by the bacteria treated with cefodizime at sub-MICs (1/8, 1/4 MIC), but other cephalosporins neither increased nor decreased the electrophoretic mobility significantly. These findings suggested that cefodizime caused a morphological change, with a decrease in negative surface charge density of K. pneumoniae, more easily than ceftazidime, cefbuperazone, cefotaxime or flomoxef, followed by an increase in the phagocytic activity of PMNs.