Use of conductance measurements to detect growth of Clostridium botulinum in a selective medium

Growth of Clostridium botulinum in a selective medium (SBM) was monitored using conductance measurements. The correlation of log 10 counts of spores and vegetative cells with detection times was highly significant (r= 0.96, 0.97; P < 0.001). Log10 counts of Cl. botulinum growing in pasteurized pork slurries also showed a clear linear relationship with detection times (r= 0.77) but the confidence limits (± log10 2.3) of the regression line were too wide to estimate numbers of Cl. botulinum. For growth studies of Cl. botulinum in pork slurries detection times were useful in determining whether or not a visually unspoiled sample contained growing cells. Knowledge that a sample contained growing cells allowed a count to be made within 24 h, whereas 48 h would elapse before results from a traditional plate count were available.