2018 Volume 67 Issue 5 Pages 755-759
We compared the promotion of B. pertussis growth and suppression of contaminating bacteria among 3 types of medium commercially available in Japan (Bordet–Gengou (BG) medium, Bordetella CFDN agar medium, and charcoal agar medium) for the isolation of Bordetella pertussis. For the assessment of growth promotion, clinical isolates of B. pertussis were used. To investigate the growth inhibition of common contaminating bacteria, ATCC strains or clinical isolates were used. Both studies were conducted in accordance with the method of Miles & Misra. When the promotion of B. pertussis growth was assessed, growth was observed up to a dilution of 10−5 on Bordetella CFDN agar medium and 10−6 on BG medium or charcoal agar medium. The mean numbers of colonies at a dilution of 10−5 were 36.5 CFU on BG medium, 20.4 CFU on Bordetella CFDN agar medium, and 40.5 CFU on charcoal agar medium. In the evaluation of inhibition of contaminating bacteria, all of the contaminants grew on BG medium, whereas charcoal agar medium inhibited the growth of all the contaminants. Bordetella CFDN agar medium did not inhibit the growth of Moraxella catarrhalis and large colonies formed, which was considered to have an adverse effect on the isolation of B. pertussis. On the basis of the above results, charcoal agar medium was found to be excellent with regard to both growth promotion and inhibition of contaminants, and thus was considered to be the most suitable medium for the isolation of B. pertussis.
