A total of 80 cases of acute exacerbation of chronic obstructive pulmonary disease admitted in pulmonary medicine ward in Siddhartha medical college, Vijayawada during the period of 18 months one & half year Jan 2008 to June 2009 of 55 years to 75 years of both males 81% to 19% were females. The three commonest organisms isolated were: 1. Pseudomonas aeruginosa in 23 cases, 2. Klebsiella pneumonia in 18 cases, and 3. Staphylococcus aureus in 14 cases. Antibiotics therapy either with levofloxacin or intravenous cefotaxime can be given if the exacerbation is not severe in case of gram negative infection. When the infection is severe, combination antibiotic therapy with cefotaxime and gentamicin or ciprofloxacin & gentamicin should be started. In cases where the infection is very severe or when the isolates are resistant to quinolones or aminoglycosides then newer antibiotics like pipericillin + Tazobactam and cefoperazone + sulbactam can be started