Single- and Dual-Species Biofilm Formation by Shiga Toxin-Producing Escherichia coli and Salmonella, and Their Susceptibility to an Engineered Peptide WK2.

Kim Stanford,Xiaolong Chen,Zhi Ma,Yan D Niu,Xia Tang,Tim A Mcallister

doi:10.3390/microorganisms9122510

Abstract

Shiga toxin-producing Escherichia coli (STEC) and Salmonella enterica are important foodborne pathogens capable of forming both single- and multi-species biofilms. In this study, the mono- and dual-species biofilms were formed by STEC O113:H21 and Salmonella enterica serovar Choleraesuis 10708 on stainless steel in the presence of beef juice over 5 d at 22 °C. The dual-species biofilm mass was substantially (p < 0.05) greater than that produced by STEC O113:H21 or S. Choleraesuis 10708 alone. However, numbers (CFU/mL) of S. Choleraesuis 10708 or STEC O113:H21 cells in the dual-species biofilm were (p < 0.05) lower than their respective counts in single-species biofilms. In multi-species biofilms, the sensitivity of S. Choleraesuis 10708 to the antimicrobial peptide WK2 was reduced, but it was increased for STEC O113:H21. Visualization of the temporal and spatial development of dual-species biofilms using florescent protein labeling confirmed that WK2 reduced cell numbers within biofilms. Collectively, our results highlight the potential risk of cross-contamination by multi-species biofilms to food safety and suggest that WK2 may be developed as a novel antimicrobial or sanitizer for the control of biofilms on stainless steel.

Highlights

Shiga toxin-producing Escherichia coli (STEC) strains are important foodborne pathogens, with beef products and fresh produce being most frequently adulterated
The severity of illnesses caused by non-O157 STEC such as O26, O45, O91, O103, O111, O113, and O145 may equal or even exceed that associated with STEC O157:H7
Salmonella enterica infections have been reported as the second leading cause of bacterial foodborne illness in the United States, responsible for approximately 11% of all infections caused by foodborne pathogens

Summary

Introduction

Shiga toxin-producing Escherichia coli (STEC) strains are important foodborne pathogens, with beef products and fresh produce being most frequently adulterated. STEC O157:H7 is the most commonly identified serotype associated with foodborne outbreaks and clinical disease, but there has been a growing incidence of non-O157 STEC infections in America since 2013 [2]. The severity of illnesses caused by non-O157 STEC such as O26, O45, O91, O103, O111, O113, and O145 may equal or even exceed that associated with STEC O157:H7. Salmonella enterica infections have been reported as the second leading cause of bacterial foodborne illness in the United States, responsible for approximately 11% of all infections caused by foodborne pathogens. It has been estimated that human infections by S. enterica are responsible for approximately 1.0 million clinical cases each year in the United States, resulting in over 19,000 hospitalizations and 378 deaths [3]

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