Themajorityofchronicobstructivepulmonarydiseaseexacerbationsarecausedbyinfectionsofthetracheobronchialtree.PreviousdataonbacterialexacerbationsofCOPDinUpperEgyptarelimited.Hence,thisstudywasconductedfortheidentificationofthecausativebacteriainexacerbationsofCOPD,andtoillustratetheirantimicrobialsusceptibilitypatternsatAssiutUniversityHospitals,UpperEgypt.Atotalof116COPDpatientswhounderwent167infectionexacerbationattacksparticipatedinthisprospectivestudy during2013.Significantbacterialgrowthwasfoundin143(86%)out ofthe167 exacerbationattacks.Themostcommondetected bacteriawereHaemophilusinfluenzae(19.4%),Escherichiacoli(18%),Streptococcuspneumoniae(16.7%),Klebsiellapneumoniae(14%),Streptococcuspyogenes(10%),Pseudomonasaeruginosa(5.6%),methicillinresistantStaphylococcusaureus(5.6%),Acinetobacter baumannii(4.2%),andMoraxellacatarrhalis(2.8%).The majority of theisolatedstrainsshowedhighresistanceratesto mostgroupsofantibioticswhere91(63%) oftheisolated strainswere multidrug resistant, 37(26%)strainswereextremedrugresistantand16(11%) bacterialstrainswerepandrugresistant.Highresistancerateswereobservedagainstpenicillinsandcephalosporins.Moderateresistanceratesweredetectedagainstthefluoroquinolones.Highsusceptibilitiesweredetectedtothecarbapenemgroup.AlltheisolatedGram-positivebacteriaweresensitivetolinezolid