The use of spiral plating and microscopic colony counting for the rapid quantitation of Mycobacterium paratuberculosis

W. L. Smith, K. L. McGarvey, James S Cullor

Research output: Contribution to journalArticle

9 Scopus citations


Aims: To evaluate a spiral plating and microscopic colony counting technique to hasten the quantitation of Mycobacterium paratuberculosis. Methods and 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 m1-1 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. Significance and Impact of the Study: The technique could greatly hasten the quantitation of viable M. paratuberculosis.

Original languageEnglish (US)
Pages (from-to)293-296
Number of pages4
JournalLetters in Applied Microbiology
Issue number5
StatePublished - 2003



  • M. paratuberculosis
  • Microscopic colonial morphology
  • Middlebrook agar
  • Mycobacteria
  • Rapid quantitation
  • Spiral plating

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Water Science and Technology
  • Fluid Flow and Transfer Processes
  • Microbiology
  • Ecology

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