Resistance to p-lactam antibiotics is an increasing problem worldwide. The emergenceof multidrug resistant bacteria is mainly associated with P- lactamase production, sodevelopment of new diagnostic and therapeutic methods is crucial to keep pace withcontinually evolving pathogens. The current research aims to diagnose and treat the P-Jactam bacterial resistance by using anti p-lactamase serum. To achieve this goal thefollowing has been done:1- E. coli and K. pneumoniae isolates obtained from different sources were resistant to~-lactams in addition to other drugs by disk diffusion sensitivity test.2- The CMY p-lactamases from a blacMY E. coli isolate was purified by lysozymebased method.3- The CMY p-lactamase extracted from standard isolate in addition to standard CMYenzyme were subjected to sodium dodecycle sulfate gel electrophoresis (SDS-PAGE)for their purity assessment and determination of their molecular weights. The proteincontent of the purified enzyme was determined by spectrophotometer.4- Polyc1onal anti-CMY p-lactamase antibodies could be produced in immunizedrabbits.5- Anti- CMY p-lactamase antibodies had the ability to combine with the extracted P-lactamase through indirect ELISA technique and detect CMY and many AmpC P-lactamases in a number of E. coli and K. pneumoniae isolates.6- Exposure of 10 resistant E. coli and K. pneumoniae isolates to p-lactams and otherdrugs under the effect of anti p-lactamase sera through broth rnicrodilution MIC testand total colony count to determine antisera effect and comparing the MIC value andcolony count before and after addition of antisera.