Acute Exacerbation of Chronic Obstructive Pulmonary Disease.Prof. Ashraf M. Hatem, MD, FCCPDefinitionofAcuteexacerbation: ThedefinitionofCOPDexacerbationisanacutechangeinapatientsbaselinedyspnoea,coughand/orsputumbeyondday-to-dayvariabilitysufficienttowarrantachangeintherapy. Causesofexacerbationcanbebothinfectiousandnon-infectiouse.g.airpollution. Mostcommonlyencounteredorganisms:-Streptococcus pneumoniae-Hemophilus influenzae-Moraxella catarrhalis Thecauseinonethirdofexacerbationsremainsuniden