RESUMEN
Beta lactamase production is an important mechanism of developing resistance to beta lactam group of antibiotics. Cephlosporins with extended spectrum of activity and stability were introduced to overcome this resistance, but soon production of extended spectrum beta lactamases (ESBLs), which are inducible in nature was reported. In this study Klebsiella aerogenes--166, Escherichia coli--120, Citrobacter spps--116, Pseudomonas spps--50, Proteus spps--32 and S. typhi--16, strains were subjected to sensitivity testing against various generations of cephalosporins by disc diffusion method and for the production of ESBLs using disc approximation method. Klebsiella aerogenes, Escherichia coli, Citrobacter spps and Pseudomonas spps showed statistically significant difference in the resistance pattern to all three generations of cephalosporins and ESBLs production.