Control of Biofilm and Planktonic Cells of Cronobacter Sakazakii, Listeria Monocytogenes, Shiga Toxin-Producing Escherichia Coli, and Salmonella Serovars Using Pressure- and Quaternary Ammonium Compound-Based Interventions

Foodborne diseases are important for public health and commerce in private industry. It is estimated that around 3,000 American adults lose their lives every year due to infectious diseases associated with consumption of contaminated food products. After and introduction chapter, the second chapter of this thesis highlights the importance of Cronobacter sakazakii and its history of outbreaks as well as recommendations to parents and caregivers. The third chapter of this thesis highlights the effects of high-pressure pasteurization for inactivation of wild-type and desiccation-adapted Salmonella serovars and C. sakazakii. At times of 0 (control), 2, 4, and 6 minutes and pressures of 200 and 500 MPa elevated hydrostatic pressure is capable of significantly reducing various phenotypes of C. sakazakii and Salmonella serovars. Fourth chapter discusses the effects of biofilm formation of O157 and non-O157 Shiga toxin-producing Escherichia coli at 7 and 25 ºC. Biofilm formation on stainless steel was observed for duration of 2 weeks. The growth was monitored and treatments with quaternary ammonium compound-based sanitizer (QUAT) were conducted on days 0, 7, and 14 at temperatures of 7 and 25 ℃. Counts of wild-type and pressure-stressed Escherichia coli O157 at 7 ºC were 2.04 ± 0.7 and 3.29 ± 0.2 prior to treatment, respectively. These counts on day-0 were reduced (p \u3c 0.05) to 0.63 ± 0.2 and 0.98 ± 0.3, respectively, after the treatment. In chapter five, a similar study and methodology was conducted using Listeria monocytogenes on surface of rubber coupons. Treatment with QUAT on day 0 was responsible for 1.71 log CFU/cm2 reduction (p \u3c 0.05) of the wild-type pathogen at 25 ºC on stainless steel coupons while the same treatment was unable to reduce (p ≥ 0.05) the pathogen biofilm counts. The sanitizer is efficacious only against planktonic cells while exhibiting inability for complete removal of one- and two-week mature biofilms