title: The use of spiral plating and microscopic colony counting for the rapid quantitation of Mycobacterium paratuberculosis.
abstract: OBJECTIVE
  To evaluate a spiral plating and microscopic colony counting technique to hasten the quantitation of Mycobacterium paratuberculosis.
  
  
  RESULTS
  Broth and milk cultures of M. paratuberculosis were spirally plated onto Middlebrook agar plates and microscopically counted at 8 and 14 days of incubation. The same plates were recounted at 27-28 days of incubation when grossly visible colonies were present. The results were statistically compared with no difference in CFU ml-1 derived from the shorter vs longer incubation times. Other mycobacteria isolates were also plated and microscopically examined and found to be easily distinguishable from M. paratuberculosis.
  
  
  CONCLUSIONS
  Microscopic quantitation of spirally plated M. paratuberculosis cultures can be achieved within 8-14 days of plate incubation and compare favourably to counts derived after prolonged incubations.
  
  
  CONCLUSIONS
  The technique could greatly hasten the quantitation of viable M. paratuberculosis.
authors.affiliation: Dairy Food Safety Laboratory, School of Veterinary Medicine, Veterinary Medicine and Teaching Research Center, University of California, Davis, CA 95616, USA. wlsmith@ucdavis.edu
authors.forename: W L
authors.initials: WL
authors.lastname: Smith
authors.forename: K L
authors.initials: KL
authors.lastname: McGarvey
authors.forename: J S
authors.initials: JS
authors.lastname: Cullor
mesh_terms: D015169:Colony Count, Microbial / Q000379:methods*; D003470:Culture Media; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification*; D012107:Research Design; D013997:Time Factors
chemical_list: D003470:Culture Media