Desiccation Tolerance and Persistence of Salmonella enterica and Cronobacter sakazakii on Food Contact Surfaces Based on Cell State and Relative Humidity.

Abstract

The persistence of foodborne pathogens on food contact surfaces (FCSs) in low-moisture food processing facilities poses significant risks for cross-contamination and foodborne illness outbreaks. This study evaluated the survival of sessile and planktonic Salmonella enterica and Cronobacter sakazakii on three common FCS materials: stainless steel (SS), high-density polyethylene (HDPE), and nitrile rubber (Buna-N). Cocktails of both pathogens were prepared as either sessile (agar-grown) or planktonic (broth-grown) cells, inoculated onto coupons at 9 log CFU/coupon, dried for 2 h, then stored for up to 90 days at 25 °C and 33 or 53% relative humidity (RH). The Weibull model was used to describe the survival of both pathogens. For S. enterica, sessile populations declined by >2 log CFU/coupon after 60 days at 33% RH and after 30 days at 53% RH, with no further reduction through 90 days. Planktonic S. enterica showed more rapid decline, particularly at 53% RH, where populations were <1 log CFU/coupon after 90 days on all FCSs. C. sakazakii exhibited greater overall desiccation resistance than S. enterica, with sessile populations declining by only 1 log CFU/coupon after 30 days at both RH conditions and remaining stable thereafter. Planktonic C. sakazakii declined by ca. 3 log CFU/coupon over 90 days at 33% RH. Weibull analysis revealed that 53% RH significantly reduced the time to first decimal reduction (δ) for both pathogens compared to 33% RH. Surface material had minimal impact on overall survival patterns, suggesting that RH and cell state are more critical determinants of pathogen persistence. This study determined that both S. enterica and C. sakazakii can persist on FCSs for extended periods under low-RH conditions, with sessile cells presenting greater survival due to enhanced desiccation resistance. These findings emphasize the importance of environmental controls in low-moisture food processing fac