The metabolism of cholesterol and certain hormonal steroids by Treponema denticola

The aim was to investigate whether reference cultures and fresh isolates of Treponema denticola are able to 5 alpha-reduce and further metabolise testosterone, 4-androstenedione, progesterone, corticosterone, cortisol or cholesterol. TWO reference and five freshly isolated cultures of T denticola were incubated with either radiolabeled or unlabeled steroid substrates; in the first case products were identified by thin layer chromatography and in the latter by gas chromatography-mass spectroscopy. All the substrates were 5 alpha-reduced. Both reference cultures and fresh isolates of T denticola presented 3 beta- and 17 beta-hydroxy steroid dehydrogenase activity. It was concluded that T denticola was capable of steroid metabolism and hypotheses are discussed regarding the in vivo function of this metabolism including, T denticola utilising host supplied steroids as growth factors and T denticola steroid metabolism acting as a virulence factor. (c) 2005 Elsevier Inc. All rights reserved.