الملخص

ABSTRACT Rhizobium leguminosarum bv.viciae was isolated and identified from root nodules of Vicia faba L. plant. Its susceptibility to 14 types of -lactam antibiotics was tested by disk diffusion method. The isolate was resistant to the following antibiotics; Amoxicillin, Carbencillin, Cephalexin, Cephradine, Cefuroxime, Cefotaxime, Ceftazidime, Cefixime, Ceftizoxime, Cefepime, and Aztreonam, while it was sensitive to only three antibiotics including; Imipenem, Cefoperazone and Ceftriaxone. The occurrence of multiple drug resistance in a soil bacterium, that is not a pathogen, suggests that chemotherapeutic use of antibiotics is not required for the development of multiple drug resistance. This may considers as a defense line to protect plant roots from pathogenic soil microorganisms.