[Studies of role of normal upper airway flora in lower respiratory tract infection by transtracheal aspiration].
D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012137:Respiratory System / Q000382:microbiology; D012141:Respiratory Tract Infections / Q000382:microbiology*; D013183:Sputum / Q000382:microbiology*; D013396:Suction / Q000379:methods