Shigatoxigenic and Enteropathogenic Escherichia coli Biofilm Formation: Effects of Different Stress Conditions on Polystyrene and Stainless Steel Surfaces

Abstract

Biofilms constitutes one of the main problems for food industry and publichealth due to the survival and the ability of pathogenic microorganisms to formthese communities on different surfaces and culture composition. Shigatoxigenic(STEC) and Enteropathogenic (EPEC) Escherichia coli are some of themicroorganisms that could form biofilms and cause serious diseases in humans.The aim of this study was to determine the capability to form biofilms of nativeSTEC and atypical EPEC (aEPEC) strains on polystyrene and stainless steel andto evaluate the effects produced by different stress conditions. The expressionof the fimbria curli was also studied. All strains were strong biofilm formers at37°C on polystyrene, except STEC O145:NM and aEPEC O130:H11 which weremoderated biofilm formers. No one strain formed biofilm at heat stress (54°C)or refrigeration (5°C) temperatures. Stainless steel surface reduced significantlythe capability to form biofilms regardless the culture composition. Most of theSTEC and aEPEC strains were curli-negative at 37°C while they showed curlipositivephenotypes at 20°C. Both curli expression and biofilm formation weresignificantly influenced by temperature and incubation time. STEC and aEPECstrains demonstrated to be able to form biofilm and produce fimbria curli underdifferent conditions of medium and temperature, which is important due the riskof survival and transmission of these pathogens from reservoirs and food tohumans.