Exacerbations in chronic bronchitis.
D001991:Bronchitis / Q000382:microbiology*; D002648:Child; D002908:Chronic Disease; D006801:Humans; D009174:Mycoplasma / Q000302:isolation & purification; D009975:Orthomyxoviridae / Q000302:isolation & purification; D012136:Respiratory Syncytial Viruses / Q000302:isolation & purification; D012229:Rhinovirus / Q000302:isolation & purification; D018139:Simplexvirus / Q000302:isolation & purification