ABSTRACT
The microscopic and colonial morphology of the individual species of Gordonia is very similar to that of Rhodococcus. Colonial morphologies observed either microscopically or macroscopically are species dependent and range from slimy to smooth or glossy and may vary from smooth to rough after 2-3 days incubation on a variety of media (e.g., blood agar media, Middlebrook 7H11 agar, brain heart infusion and heart infusion agar). The color of the colonies, often not apparent until at least 7 days of incubation at optimal temperature, also varies through a wide range, from white, cream, beige, or pink, to the more classic orange-salmon color of most Gordonia species. The organisms are gram-positive with coccoid to bacillary forms that may be weakly acid fast (4-10 organisms per oil immersion Šeld) with the modiŠed Kinyoun (1% sulfuric acid) stain. Brie³y, all members of the genus are aerobic, nonsporeforming, gram-positive nocardioforms with an oxidative carbohydrate metabolism.
