Heat-resistant and biofilm-forming Escherichia coli in pasteurized milk from Brazil

Evolution of pathogenic Escherichia coli harboring the transmissible locus of stress tolerance: from food sources to clinical environments

Escherichia coli (E. coli) carrying the transmissible locus of stress tolerance (tLST) are able to overcome numerous environmental challenges. In our in-silico study, we aimed to characterize tLST in terms of its variants in 793 genomes of E. coli from Brazil originating from food, environmental and clinical (animal and human) sources, and to perform a temporal analysis in order to identify the historical moment of its emergence. We also analyzed the presence of two Yersinia high pathogenicity island (HPI) variants in E. coli genomes, describing other genes and accessory for resistance, persistence, mobile elements (plasmids) and sequence types. The prevalence of the tLST was 10% in E. coli from Brazil, predominantly observed in milk-originating genomes, within the prevalent tLSTCP010237 variant. In E. coli from other sources (clinical/environmental), only part of the tLST was present. Remarkably, our temporal analysis pinpointed the emergence of tLST back to around 1914, coinciding with major societal events. Regarding virulence genes, we found a prevalence of 38.5% for HPI of Y. pestis across genomes from all sources. Our global analysis also showed a high diversity of other virulence genes for milk E. coli (+ 100 genes). These genomes also stood out from the overall metadata for presenting a greater variety of resistance genes to other stresses, such as metals, biocides and acids, as well as persistence genes (biofilm formation). This study demonstrated the historical background of E. coli with tLST genes dating back more than 100 years, and the acquisition of a wide range of virulence and resistance genes that allow it to circulate in different environments: from food to clinic or from clinic to food, making this bacterium a pathogen that requires rigorous surveillance and strategic interventions to mitigate potential risks.

Unveiling the High Diversity of Clones and Antimicrobial Resistance Genes in Escherichia coli Originating from ST10 across Different Ecological Niches

In this pioneering in silico study in Peru, we aimed to analyze Escherichia coli (E. coli) genomes for antimicrobial resistance genes (ARGs) diversity and virulence and for its mobilome. For this purpose, 469 assemblies from human, domestic, and wild animal hosts were investigated. Of these genomes, three were E. coli strains (pv05, pv06, and sf25) isolated from chickens in our previous study, characterized for antimicrobial susceptibility profile, and sequenced in this study. Three other genomes were included in our repertoire for having rare cgMLSTs. The phenotypic analysis for antimicrobial resistance revealed that pv05, pv06, and sf25 strains presented multidrug resistance to antibiotics belonging to at least three classes. Our in silico analysis indicated that many Peruvian genomes included resistance genes, mainly to the aminoglycoside class, ESBL-producing E. coli, sulfonamides, and tetracyclines. In addition, through Multi-locus Sequence Typing, we found more than 180 different STs, with ST10 being the most prevalent among the genomes. Pan-genome mapping revealed that, with new lineages, the repertoire of accessory genes in E. coli increased, especially genes related to resistance and persistence, which may be carried by plasmids. The results also demonstrated several genes related to adhesion, virulence, and pathogenesis, especially genes belonging to the high pathogenicity island (HPI) from Yersinia pestis, with a prevalence of 42.2% among the genomes. The complexity of the genetic profiles of resistance and virulence in our study highlights the adaptability of the pathogen to different environments and hosts. Therefore, our in silico analysis through genome sequencing enables tracking the epidemiology of E. coli from Peru and the future development of strategies to mitigate its survival.

Biofilm-producing Escherichia coli O104:H4 overcomes bile salts toxicity by expressing virulence and resistance proteins

We investigated bile salts' ability to induce phenotypic changes in biofilm production and protein expression of pathogenic Escherichia coli strains. For this purpose, 82 pathogenic E. coli strains isolated from humans (n = 70), and animals (n = 12), were examined for their ability to form biofilms in the presence or absence of bile salts. We also identified bacterial proteins expressed in response to bile salts using sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-electrophoresis) and liquid chromatography-mass spectrometry (LC-MS/MS). Lastly, we evaluated the ability of these strains to adhere to Caco-2 epithelial cells in the presence of bile salts. Regarding biofilm formation, two strains isolated from an outbreak in Republic of Georgia in 2009 were the only ones that showed a high and moderate capacity to form biofilm in the presence of bile salts. Further, we observed that those isolates, when in the presence of bile salts, expressed different proteins identified as outer membrane proteins (i.e. OmpC), and resistance to adverse growth conditions (i.e. F0F1, HN-S, and L7/L12). We also found that these isolates exhibited high adhesion to epithelial cells in the presence of bile salts. Together, these results contribute to the phenotypic characterization of E. coli O104: H4 strains.

Modeling and optimization of non-thermal technologies for animal-origin food decontamination

Non-thermal technologies (NTT) have been primarily studied for obtaining animal-origin products with improved bacteriological stability, aiming to eliminate the main foodborne pathogens associated with outbreaks, e.g., Salmonella spp., Escherichia coli, Campylobacter jejuni, Listeria monocytogenes, Staphylococcus aureus, Bacillus spp., and Clostridium perfringens, but avoiding the use of heat, leading to energy savings. On the other hand, due to the novelty of these technologies, there is a lack of standardization in their use and, consequently, a reduction in the process efficiency and undesirable changes in the physicochemical, nutritional, and sensory characteristics of food. Therefore, there is a need to utilize mathematical approaches for developing the modeling, validation, and optimization of NTT aiming the pathogen inactivation. In this context, the Box-Behnken design (BBD) and the central composite rotatable design (CCRD) have been severely explored due to the possibility of developing second-order polynomial models based on the linear, quadratic and interaction behaviors of the independent variables, but with a lower number of experiments. In this chapter, we summarized the principles and fundamentals of pathogen inactivation using the main NTT, e.g., high-pressure processing (HPP), ultraviolet C radiation (UV-C), high-intensity ultrasound (HIUS), cold atmospheric plasma (CAP) and pulsed electric field (PEF), as well as the principles of use of BBD and CCRD and their recent application for modeling and optimization of the NTT.