title: An inexpensive solid medium for obtaining colony-forming units of oral spirochetes.
abstract: A method for the enumeration of colony-forming units of oral anaerobic spirochetes in new oral spirochete agarose (NOS-A) medium was described recently. However, the high cost of agarose limits the extent to which large assays can be carried out. Accordingly, a search for an inexpensive gelling agent that remains molten at 37 degrees C and gels at 25 degrees C was undertaken. Varying amounts of Noble agar or Bacto agar (0.5 to 1.5%, w/v) were mixed with varying amounts of gelatin (0.5 to 1.0%, w/v) in NOS medium. NOS medium containing 0.5% gelatin-0.5% Noble agar (NOS-GN) or 0.5% gelatin-0.5% Bacto agar (NOS-GB) met the above criteria. NOS-GN and NOS-GB media yielded higher colony-forming units with Treponema denticola than NOS-A medium in that order. However, all three media, NOS-GN, NOS-GB and NOS-A, performed equally well in the recovery of viable counts of T. vincentii. The NOS-GN medium was not liquefied by subgingival bacteria or two gelatinase-producing species of bacteria, Bacillus subtilis and Staphylococcus aureus. Thus NOS-GN medium is the recommended medium both in cost and performance for obtaining colony counts of spirochetes.
authors.affiliation: Faculty of Dentistry, McGill University, Montreal, Quebec, Canada.
authors.forename: E C
authors.initials: EC
authors.lastname: Chan
authors.forename: A
authors.initials: A
authors.lastname: De Ciccio
authors.forename: R
authors.initials: R
authors.lastname: McLaughlin
authors.forename: A
authors.initials: A
authors.lastname: Klitorinos
authors.forename: R
authors.initials: R
authors.lastname: Siboo
mesh_terms: D001412:Bacillus subtilis / Q000302:isolation & purification; D015169:Colony Count, Microbial / Q000379:methods; D003470:Culture Media; D003773:Dental Plaque / Q000382:microbiology; D005780:Gelatin; D005782:Gels; D006801:Humans; D009055:Mouth / Q000382:microbiology*; D010514:Periodontal Pocket / Q000382:microbiology; D013144:Spirochaetales / Q000302:isolation & purification*; D013211:Staphylococcus aureus / Q000302:isolation & purification; D013696:Temperature; D014208:Treponema / Q000302:isolation & purification
chemical_list: D003470:Culture Media; D005782:Gels; D005780:Gelatin