Ceftriaxone-Sulbactam Combination: Microbial Analysis by Variation of Ratios and Comparative Disc Diffusion

Development of β-lactamase provides resistance to bacteria against cephalosporins. Ceftriaxone, a third generation cephalosporin has also lost it's effectiveness in clinical practices. However, it is the current trend to use combinations of β-lactam antibiotics and β-lactamase inhibitors as they have come up as the ideal solution. The potential combination with ceftriaxone is of sulbactam, a β-lactamase inhibitor. This combination is used in clinical practice for achieving better therapeutic value. In present study, comparative microbial analysis of various ratios of ceftriaxone, sulbactam and sulbactomax, a Fixed Dose Combination (FDC) of ceftriaxone and sulbactam has been performed by Minimum Inhibitory Concentration (MIC) analysis. Comparative evaluation of susceptibility discs of FDC of ceftriaxone and sulbactam with ceftriaxone is done under time stress to find out possibility of development of resistance in Staphylococcus aureus, Klebsiella pneumoniae, Proteus vulgaris, Escherichia coli and Methicillin Resistant Staphylococcus aureus (MRSA). In the results of MIC, 2:1 ratio of ceftriaxone: sulbactam has shown better bactericidal activity than the ratio of 1:6.66 and 1:3.33. Antibiotic Susceptibility Test (AST) demonstrated that ceftriaxone-sulbactam, apart from being more bactericidal, has less chances of resistance development, when compared with ceftriaxone alone. It may be concluded that ceftriaxone-sulbactam in the ratio of 2 :1 has better bactericidal properties and reduces the probability of resistance development.