The Anaerobic Microflora: The Accused in Oral Malodour?

Background: Oral malodour is foul-smelling breath from the oral cavity and is due to metabolic products of bacteria in the oral cavity but can also be caused by many other systemic diseases. Oral malodour is believed to originate from foul-smelling gases, such as hydrogen sulfide produced by oral bacteria. Aim: To identify hydrogen sulfide producing bacteria from tongue biofilm and to investigate the relationship between bacterial flora and hydrogen sulphide levels in the oral cavity. Materials and Methods: Oral malodour levels in 26 subjects (aged 16-69 years) were assessed by portable volatile sulfide monitor Halimeter and gas chromatography. They were accordingly divided into two groups: an odour group and a no/low odour group. Tongue coatings were sampled and organisms were categorized. Results: Tongue coatings were spread onto sheep blood agar (anaerobic) containing Casein enzymic hydrolase, Papaic digest of soyabean meal, yeast extract, sodium chloride, L-cysteine, Hemin, and Agar at final pH (at 25 0 C) 7.4±0.2. The plates were incubated at 3