In vitro activity of commonly used antimicrobial agents against several clinical isolates were studied. In the case of E. coli, the MICs at which 90% of the bacteria are inhibited of ampicillin, Unasyn, cefazoline, cefotaxim, carbenicillin, gentamicin and ofloxacin were 100<, 100, 25, 0.2, 100<, 3.13, and $12.5{;}mu extrm{g}/m$ , respectively. In the case of K . pneumoniae, the MICs at which 90% of the bacteria are inhibited of ampicillin, Unasyn, crfazoline, cefotaxim, carbenicillin, gentamicin and ofloxacin were 100<, 12.5, 100<, 0.1, 100<, 1.6, and $0.4{;}mu extrm{g}/m$ , respectively. In the case of Enterobacter sp, the MICs at which 90% of the bacteria are inhibited of ampicillin, Unasyn, cefazoline, cefotaxim, carbenicillin, gentamicin and ofloxacin were 100<, 100, 100<, 6.25, 100<, 100 and $1.57{;}mu extrm{g}/m$ , respectively. In the case of Acinetobacter sp, the MICs at which 90% of the bacteria are inhibited of ampicillin, Unasyn, cefazoline, cefotaxim, carbenicillin, gentamicin and ofloxacin were 100<, 100<, 100<, 100<, 100< 100< and $50{;}mu extrm{g}/m$ , respectively. In the case of Pseudomonas sp, the MICs at which 90% of the bacteria are inhibited of ampicillin, Unasyn, cefazoline, cefotaxim, carbenicillin, gentamicin and ofloxacin were 100<, 100<, 100<, 50, 100<, 25 and $25{;}mu extrm{g}/m$, respectively. In the case of S. aureus, the MICs at which 90% of the bacteria are inhibited of ampicillin, Unasyn, cefazoline, cefotaxim, carbenicillin, gentamicin and ofloxacin were 50, 50, 100<, 100<, 50, 50, and $100{;}mu extrm{g}/m$, respectively.