Microbiologcal Studies on the in vitro susceptibility & Resistance of Egyptian Clinical Isolates of staphylococcus Aureus and Escherichia Coli to different B-Lactom Antibiotics

The minimum inhibitory concentration of H, B-lactam antibiotics on 94 S.aureus and 91 E.coli isolate collected from Egyptian patients were determined by the tube dilution method1- The following concentrations of the antibiotics proved to causes 50% inhibition of the isolates :a – In case of S. aureus isolated :- Penicillins , 0.7 ug/ml of dicloxacillin , 10 ug/ml of amoxcyilin 18.75 ug/ml of both ampicillin and epicillin , 35 ug / ml of ticarcillin and > 100 ug / ml of benzylpenicillin- Cephalosporine , 2.0 ug/ml of cephaloridine , 2.5 ug/ml of cefuroxime . 2.6 ug/ml of celazoline , 9.4 ug/ml of cephalexin and 18.75 ug/ml of cefradineb- In case of E.Coli :- Penicillins , 31.3 ug/ml of amoxicillin , and > 100 ug/ml of ampicillin , epicillin ticarcillin , dicloxacillin and benzylpenicillin- Cephalosporins , 23.8 ug/ml of cefuroxime , 25 ug/ml of cefazohne , 37.8 ug/ml of cephaloridine and > 100 ug/ml for both cephalexin and cefradine2- The B-lactamase production by the microbial isolates was detected it was found that 78.7of S.aureus and 73.6% of E.coli isolates were B-lactamase producers .