Evaluation of Salmonella Biofilm Cell Transfer from Contact Surfaces to Beef Products

Introduction: Meat contamination by Salmonella enterica is a serious food safety concern. One common transmission route that leads to cross contamination is bacteria transfer from biofilms on contact surfaces to meat products via direct contact. Many factors could affect biofilm transfer efficiency, including biofilm forming ability, food product composition and the type of contact surface materials. We evaluated the impact of these factors on Salmonella biofilm cell transfer from common contact surfaces to beef products. We also determined Salmonella prevalence after beef products contacting solid surfaces colonized by Salmonella biofilms. 

Purpose: To evaluate the effects of biofilm forming ability, meat surface composition and contact surface materials on Salmonella biofilm cell transfer efficiency.  

Methods: Four strains of Salmonella serotypes Anatum and Dublin were used to quantify enumerable amount of bacteria transferred from biofilms on solid surfaces to beef products after direct/consecutive contacts. The effect of direct contact with biofilm-colonized surface on Salmonella prevalence rate in beef products was determined after sample enrichment.   

Results: Effective transfer of Salmonella cells from biofilms on solid surfaces to beef products via direct contact was observed. Biofilm forming potency had the most significant effect on transfer efficiency. Contact surface materials also affected the transfer as biofilms on stainless steel surface appeared to transfer more efficiently than those on polyvinyl chloride plastic surface (P<0.05). Conversely, meat surface composition (muscle or fat tissues) showed no significant effect on biofilm transfer efficiency.  Importantly, after enrichment all beef samples that contacted Salmonella biofilms exhibited positive Salmonella prevalence, including samples with no enumerable transferred Salmonella cells.  

Significance: These data indicate that Salmonella biofilms, even at low levels, still present a serious risk of causing cross-contamination, thus, highlight the importance of proper sanitization procedures in meat plants.