In recent years bacteria have shown much more potential to develop antimicrobial resistance. This mandates not only to the development of new drugs but also to the re-evaluation of already existing ones. Present study is sought to evaluate the in vitro activity of a few newer antibiotics which are not marketed in many countries at present. This study evaluates the in vitro activity of newer antibiotics i. e arbekacin, cefminox, fosfomycin and biapenem against clinical isolates Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii. The minimum inhibition concentration of antibiotics was determined by the agar dilution method. The main finding of the present study is that fosfomycin was active against both E. coli and K. pneumoniae where as cefminox exhibited an insignificant intermediate level activity against both E. coli and K. pneumoniae. Biapenem was more active on E. coli than other tested organisms. Colistin showed inhibition for the entire organisms in present study. The present study suggests that colistin and fosfomycin are promising antibiotics for future use; however clinical trials are needed to confirm these findings and to evaluate potency of these four antibiotics.
