A comparative study of in vitro activity of amikacin, gentamicin, netilmicin, tobramycin and isepamicin was done. A total of 200 clinical isolates of Gram negative organisms from various clinical sources were tested. E.Coli was the most frequently isolated organism followed by Pseudomonas
spp. and Enterobacter
spp. Of the 5 aminoglycosides tested, isepamicin showed the highest numbers of susceptible isolates followed by amikacin, netilmicin, gentamicin and tobramycin. MIC 90 value of isepamicin was lower as compared to amikacin.