Flow cytometric method for the assessment of the minimal inhibitory concentrations of antibacterial agents to Mycoplasma agalactiae

Authors Organisations
  • Patrícia Assunção(Author)
    University of Las Palmas de Gran Canaria
  • Nuno T. Antunes(Author)
    University of Las Palmas de Gran Canaria
  • Ruben S. Rosales(Author)
    University of Las Palmas de Gran Canaria
  • Christian de la Fe(Author)
    University of Las Palmas de Gran Canaria
  • Carlos Poveda(Author)
    University of Las Palmas de Gran Canaria
  • José B. Poveda(Author)
    University of Las Palmas de Gran Canaria
  • Hazel Davey(Author)
Type Article
Original languageEnglish
Pages (from-to)1071-1076
Number of pages6
JournalCytometry Part A
Volume69A
Issue number10
Early online date22 Sep 2006
DOI
Publication statusPublished - 01 Oct 2006
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Abstract

In this study, flow cytometry was evaluated for the determination of the minimal inhibitory concentrations (MIC) of seven antibacterial agents (enrofloxacin, ciprofloxacin, gentamicin, streptomycin, chloramphenicol, oxytetracycline, and tylosin) on Mycoplasma (M.) agalactiae. Flow cytometry was able to detect M. agalactiae inhibition from 6 h postincubation, although it seems that definitive MIC values determined by flow cytometry were only possible at 12-h postincubation. However, the results obtained by the traditional method were only obtained at 24 h, when a visible change in the medium had occurred. At 24 h, both methods gave the same result for six antibacterial agents (enrofloxacin, ciprofloxacin, gentamicin, streptomycin, chloramphenicol, and oxytetracycline); whereas flow cytometry gave slightly higher MIC for tylosin. This was attributed to the fact that the M. agalactiae growth that had occurred in the tubes containing tylosin was not enough to visibly change the color of the medium. Futhermore, flow cytometry detected that inhibitory concentrations of oxytetracycline, chloramphenicol, and tylosin as judged at 24 h were not able to inhibit the M. agalactiae growth after 48 h. MIC values of enrofloxacin and ciprofloxacin were sufficient only to maintain the total counts per milliliter throughout the time matched samples, whereas higher concentrations of theses antibacterial agents reduced the total counts per milliliter over the course of the experiment. The main advantage of the flow cytometric method is that MIC results for M. agalactiae can be obtained in a shorter time than is possible with the traditional method. The method presented makes identification of resistant populations of M. agalactiae possible and, unlike the traditional method, allows the effect of each antibacterial agent to be determined in real-time at the single-cell level.

Keywords

  • cytometry, MIC, Mycoplasma agalactiae, susceptibility, antibiotics