Survival of Campylobacter jejuni on various fresh produce

The survival of seven human and two chicken Campylobacter jejuni strains, with known Penner heat-stable (HS) serotypes and pulsed-field gel electrophoresis (PFGE) genotypes, was investigated on fresh-cut iceberg lettuce. In addition, the survival of four selected C. jejuni strains was assessed on cantaloupe pieces, cucumber slices, grated carrot and strawberries. Fresh produce was inoculated with 105 to 107 colony-forming units (CFU) of C. jejuni per gram, and the bacterium was enumerated using standard procedures after sample storage at 7 and 21 °C for 24, 48 and 72 h. The absolute values of the slopes (death rates) of the survival curves (log10 CFU/g versus time) were calculated and compared. At 7 °C, the mean death rates (day−1) were 0.44 on cantaloupe, 0.41 on cucumber slices, 0.43 on grated carrot, 0.59 on iceberg lettuce and 1.02 on strawberries. The corresponding death rates (day−1) at 21 °C were 1.52, 1.55, 2.61, 1.39 and 8.74. The death rate of C. jejuni on strawberries (pH 3.4) was significantly (P<0.05) higher than on other produce. Moreover, the death rate at 21 °C as compared with 7 °C was significantly higher (P<0.05). Minor differences were observed in the survival of different C. jejuni strains. Our results suggest that after contamination of fresh produce, including strawberries, C. jejuni may survive sufficiently long to pose a risk to the consumer.