Introduction:Both the prevalence and mortality from COPD has been increasing worldwide.Recent studies have described a relationship between lung function decline and respiratory infections. Studies of sputum and bronchoscopy samples using standard culture and molecular techniques have clearly demonstrated that COPD is associated with a markedly increased prevalence of bacteria. Sputum cultures are still useful in researching the pathogenesis of COPD, as they provide the pathogens to be studied further . Aim: To study the association of microbial pattern with severity i.e. stages in patients of COPD, if any.Methods: 200 clinically diagnosed cases of AECOPD of age ≥45 years were recruited in study. Two sputum samples each were processed by conventional methods. Preparation of media, reagents, Gram staining, identification of culture isolates, antibiotic sensitivity tests and pulmonary function testing were carried out.Conclusion: Shifting from predominantly gram positive to gram negative isolates were observed with shifting of stages from mild to very severe stage ( gram positive and gram negative bacteria were 90 % and 10% in mild stage ,12.77% and 31.60 % in moderate stage, 17.60 % and 82.40 % in severe stage and 7.45 % and 85.50 % in very severe stages of COPD).