Comparative study of antibacterial activity of cefazolin sodium and of its crystalline modifications

Antibacterial activity of four crystalline modifications (ground, solvated and two desolvated) of cefazolin sodium (CZS) have been studied. Their antibacterial properties have been determined by means of minimal inhibitory concentrations (MIC(50) and MIC(90)) and of disk diffusion inhibition zone values. The above-mentioned crystalline modifications (Mod.) of CZS-I, II, III and IV, respectively, have been shown to have differences in their antibacterial properties in comparison with the trade CZS as well as between themselves. Mod. I has higher or the same activity as CZS. The obtained results we have explained with the formation of different intermolecular H-bonds in the modifications could be due to the rotation about C(alpha)- C' and C-N bonds in the amide groups in their molecules.