Survival of Campylobacter jejuni and Campylobacter coli on retail broiler meat stored at -20, 4, or 12 degrees C and development of Weibull models for survival.

Survival of Campylobacter jejuni and Campylobacter coli isolated from broiler meat was investigated and modeled on retail breast meat. Meat portions were inoculated with C. jejuni or C. coli at 6.4 to 6.8 log CFU/g followed by storage at -20 degrees C for 84 days or at 4 or 12 degrees C for 14 days. Kinetic data within a species and temperature were fitted to the Weibull model. When >or=70% of the residuals were in an acceptable prediction zone from -1 (fail-safe) to 0.5 (fail-dangerous) log units, the model was considered to have acceptable performance. Survival of Campylobacter was highest at 4 degrees C, lowest at 12 degrees C, and intermediate at -20 degrees C. Survival of C. jejuni and C. coli was similar at -20 degrees C but was lower (P<0.05) for C. jejuni than for C. coli at 4 and 12 degrees C. The Weibull model provided acceptable predictions for four of six sets of dependent data with unacceptable performance for survival of C. jejuni at -20 and 12 degrees C. A difference in survival was observed between the two strains of C. jejuni tested. Comparison of Weibull model predictions with data for C. jejuni archived in ComBase revealed mostly unacceptable performance, indicating that C. jejuni and C. coli survival on raw broiler breast meat differs from published results for other strains and growth media. Variation in Campylobacter survival among replicate storage trials was high, indicating that performance of the models can be improved by collection of additional data to better define the survival response during storage at temperatures from -20 to 12 degrees C.

Use of cellulose filters to isolate Campylobacter spp. from naturally contaminated retail broiler meat.

Membrane filtration has been used to isolate Campylobacter spp. from feces, although approximately 5 log CFU/g must be present in the sample. Few studies have attempted to use filter membranes for the isolation of Campylobacter from foods. We investigated the minimum number of thermotolerant Campylobacter cells that pass through cellulose filters, the effect of different cell conditions on the rate of passage, and the minimum number of cells that could pass the filters from enriched broiler meat naturally contaminated with Campylobacter spp. Cellulose filters with 0.65-microm pore sizes retained fewer cells and were more effective than filters with 0.45-microm pore sizes. Scanning electron microscopy revealed that 15 min of contact of the filters with agar plates allowed for the passage of most bacteria. The minimum number of bacteria required to pass through the filters was contingent on cell conditions; nonmotile cells were retained more than motile cells (P < 0.05). The minimum number of motile bacteria from 24-h cultures and centrifuged cells were 2.2 and 2.1 log CFU, respectively, while the number of coccoid and nonmotile (flaA/B(-) mutant) cells were 4.1 and 3.4 log CFU, respectively. Broiler meat samples enriched in Bolton's broth supplemented with 5% lysed blood showed that approximately 1.7 log CFU of Campylobacter can be filtered to pure colonies on agar plates. These results demonstrate that the motility of the bacteria influences passage through cellulose filters and that 0.65-mum-pore-size filters on agar plates help obtain pure Campylobacter colonies from enriched food samples.