Isolation of Branhamella catarrhalis from sputum and tracheal aspirate

Branhamella catarrhalis was suggested by the presence of gram-negative intracellular diplococci and confirmed by quantitative culture of the expectorated sputa of 11 patients with clinical evidence of lower respiratory tract infection. In quantitative culture, more than 20 colonies of B. catarrhalis were seen in each of the liquefied expectorated sputa at a dilution of 10(-7). Transtracheal aspirations were then performed on these 11 patients, and B. catarrhalis was isolated from the lower respiratory tract secretions of 10 of the patients. Of the 10 isolates, 5 produced beta-lactamase. None of the isolates grew on modified Thayer-Martin medium. The presence of gram-negative intracellular diplococci and the growth of B. catarrhalis on quantitative culture of expectorated sputum reliably indicates the presence of B. catarrhalis in the lower respiratory tract.