Effect of recovery medium on the isolation of Campylobacter jejuni before and after heat treatment.

The effect of various concentrations of polymyxin B and Colistin in Skirrow’s or Butzler’s type media, respectively, on the recovery rate of 13 strains of G. jejuni before and after heat treatment was studied. Prior to heating, a Butz-ler’s type medium containing 40 I.U. per ml Colistin was inhibitory for certain strains of C. jejuni. After heating at 48° G for 30 min, media containing 2.5 I.U. per ml polymyxin B or 10 I.U. per ml Colistin were not inhibitory for heat-injured cells. When the concentrations of polymyxin B were increased to 5.0 I.U. per ml or those of Colistin to 20 or 40 I.U. per ml in the selective media, the means of the differences of log cell counts between non-selective Brucella blood agar and the selective media was statistically significant (P < 0.05). The mean D-value of G. jejuni strains in Brucella broth at 48° G was 18.4±5.4 min.