Biochemical reactions Members of the genus Bordetella are relatively inert biochemically. None ferment sugars; gelatin is not liquefied; indole and acetoin are not produced; H2S is not produced; most strains are weakly catalase positive; and litmus milk is usually rendered alkaline. The production of an alkaline reaction in most media is characteristic. B. bronchiseptica is rapidly urease positive. Culturing B.bronchiseptica B. bronchiseptica infection is best diagnosed from oro-pharyngeal swabs, or from swabs of nasal discharge. Samples should be taken using sterile cotton wool swabs, placed into charcoal transport medium before plating on to a selective medium such as Bordet-Gengou (BG) agar. B. bronchiseptica grows rapidly, with colonies evident on BG agar under a dissecting microscope within 48 hours (figure 1). Microscopic examination B. bronchiseptica are small (0.2 mm X 0.7 mm), aerobic, motile, Gram negative coccobacilli which occur singly, in pairs, or in small clumps. Due to the slow uptake of the safranin used in the Gram stain, pale staining is characteristic (figure 2).