Consecutive treatments with a multicomponent sanitizer inactivate biofilms formed by Escherichia coli O157:H7 and Salmonella enterica and remove biofilm matrix

Authors: Wang, Rong; ZHOU, YOU - University Of Nebraska; Kalchayanand, Norasak - Nor; Harhay, Dayna; Wheeler, Tommy

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2020
Publication Date: 3/1/2021
Citation: Wang, R., Zhou, Y., Kalchayanand, N., Harhay, D.M., Wheeler, T.L. 2021. Consecutive treatments with a multicomponent sanitizer inactivate biofilms formed by Escherichia coli O157:H7 and Salmonella enterica and remove biofilm matrix. Journal of Food Protection. 84(3):408-417. https://doi.org/10.4315/JFP-20-321.
DOI: https://doi.org/10.4315/JFP-20-321

Interpretive Summary: Biofilms are surface-attached bacterial communities that are highly tolerant against sanitization. Many foodborne pathogens including E. coli O157:H7 and Salmonella enterica can develop strong biofilms on contact surfaces at meat processing plants and cause product contamination, therefore it is important to inactivate and remove these biofilms and further prevent their reoccurrence. We evaluated the effectiveness of multiple consecutive treatments with a multicomponent sanitizer, a product mainly consisting of hydrogen peroxide and quaternary ammonia compounds, against biofilms by E. coli O157:H7 and Salmonella enterica strains. Our results showed that while applied as foam or liquid solution, this sanitizer was effective at its recommended concentration combined with multiple consecutive treatments and sufficient exposure time to inactivate biofilm cells and control pathogen recovery growth. Electron microscope examination showed that the sanitizer treatment removed the majority of the surface biofilms and changed bacterial shape and cell length, resulting in severe cell injury and death. Our study indicated that consecutive treatments with a hydrogen peroxide and quaternary ammonia sanitizer is effective in inactivating E. coli O157:H7 and Salmonella enterica biofilms and preventing pathogen reoccurrence and provides meat processors with a readily implementable strategy to improve meat safety.

Technical Abstract: Many foodborne pathogens, including Escherichia coli O157:H7 and Salmonella enterica, can develop biofilms on contact surfaces at meat processing plants. Owing to the high tolerance of the biofilm cells associated with the three-dimensional biofilm structure and the well-expressed bacterial extracellular polymeric substances, it is a real challenge to completely inactivate and remove mature biofilms, as well as further prevent biofilm reoccurrence and pathogen survival. In the present study, we evaluated the effectiveness of consecutive treatments (10 to 120 min per treatment) by repeatedly applying a multicomponent sanitizer, based on a functional mechanism by synergistic combination of hydrogen peroxide and quaternary ammonia compounds, against biofilms formed by E. coli O157:H7 and S. enterica strains. Biofilms on stainless steel surfaces were treated with 2.5, 5, or 10% (recommended working concentration) of the sanitizer applied as a foam or liquid solution. Our results showed that the multicomponent sanitizer significantly (P < 0.05) reduced the amount of viable biofilm cells at all concentrations, as enumerable bacteria were only detected after low-concentration treatments (2.5 or 5%) with short exposure periods (10 or 20 min per treatment). Treatments with high concentrations (5 or 10%) of the sanitizer, multiple consecutive treatments (2 or 3 treatments), and sufficient exposure time (>60 min per treatment) effectively controlled pathogen survival postsanitization. Examination with a scanning electron microscope showed that treatment with the sanitizer at 5% strength significantly dissolved the connecting extracellular polysaccharide matrix and removed the majority of the biofilm matrix. No intact biofilm structure was detected after the 10% sanitizer treatment; instead, scattered individual bacteria with visibly altered cell morphology were observed. The treated bacteria exhibited indented and distorted shapes with shortened cell length and increased surface roughness, indicating severe cell injury and death. Our observations indicated that consecutive treatments with the multicomponent sanitizer was effective in inactivating E. coli O157:H7 and S. enterica biofilms and preventing pathogen reoccurrence.