Roxithromycin antagonism with essential and trace elements

In order to ascertain the role of various essential and trace element complexation on the antibacterial activity of various macrolide antibiotics, the synergistic or antagonistic behavior of roxithromycin metal complexes have been studied and compared with the parent drug. Metal complexes of roxithromycin with magnesium, calcium, chromium, manganese, iron, cobalt, nickel, copper, zinc and cadmium have been investigated for their antibacterial activity and compared with roxithromycin by observing the changes in minimum inhibitory concentration (MIC) and by measuring the zone of inhibition of complexes against both Gram-negative and Gram-positive microorganisms. Various microorganisms used were Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Salmonella typhi, Proteus vulgaris, Shigella dysentery, Klebsiella pneumoniae and Staphylococcus epidermidis. For MIC observation, serial dilution method was employed and zone sizes were determined by diffusion disk method. Our investigations divulge that formation of roxithromycin complexes results in antagonistic behavior against few microorganisms where in MIC is increased with respect to the parent drug, while against most of the microorganism, there was no effect on the MIC of the roxithromycin metal complexes with respect to parent roxithromycin.