Acinetobacter baumannii is a nonfermentative, gram negative coccobacilli.particular A.baumannii plays a significant role in the colonization and infection of patients admitted to hospitals, especially those in intensive care units such as bacteraemia, urinary tract infection, meningitis and predominantly nosocomial pneumonia, particularly ventilator associated pneumonia (VAP.The infections caused by Acinetobacter spp. are often extremely difficult for the clinician to treat because of the widespread resistance of these bacteria to the major groups of antibiotics like aminoglycosides, fluoroquinolones, ureidopenicillins and third generation cephalosporins.The most prevalent mechanism of beta-lactam resistance in A. baumannii is enzymatic degradation by beta-lactamases. ESBL,MBL and AmpC types of beta lactamases have been identified in Acinetobacter spp causing resistance to beta lactams.