TY - JOUR TI - Contact time and its effect on cross-contamination of enterobacter aerogenes from surfaces to foods DO - https://doi.org/doi:10.7282/T3W95CCN PY - 2016 AB - Bacterial cross-contamination from surfaces to food can be a common factor contributing to foodborne disease outbreaks, while the popular culture notion of the "five second rule" states food dropped on the floor for less than five seconds is “safe”, because bacteria need time to transfer. The rule has been explored only to a limited degree in the published literature and popular culture. The cross-contamination rate of Enterobacter aerogenes was evaluated on common surfaces using scenarios that differ by surface type, food type, contact time (0, 5, 30 and 300 s), and inoculum matrix (TSB or peptone buffer). The surfaces used were stainless steel, ceramic tile, wood and carpet. The food types were watermelon, bread, bread with butter and gummy candy. Surfaces were spot inoculated with 1 ml of inoculum and allowed to dry for 5 h, yielding an approximate concentration of 107 CFU/surface. Foods were dropped on the respective surfaces from a height of 12.5 cm and left to rest for the appropriate time. Post transfer surfaces and food were placed in sterile filter bags and homogenized or massaged, diluted and plated on tryptic soy agar. The transfer rate was quantified by determining the log % transfer from the surface to the food. Contact time, food and surface type all had a highly significant effect (P < 0.000001) on log % transfer of Enterobacter aerogenes from surface to food. The inoculum matrix (TSB or peptone buffer) also had a significant effect on transfer (P = 0.012944), and most of the interaction terms had a significant effect on transfer. More bacteria transferred to watermelon (~ 0.2-97%) relative to other food types studied, while fewer bacteria transferred to gummy candy (~0.1-62%). Transfer of bacteria to bread (~0.02-94%) and bread with butter (~0.02-82%) were similar, and transfer rates under a given set of condition were more variable compared to watermelon and gummy candy. KW - Food Science KW - Food contamination KW - Enterobacter aerogenes LA - eng ER -