Characterization of Escherichia coli possessing the locus of heat resistance isolated from human cases of acute gastroenteritis

Ma, Angela; Glassman, Heather; Chui, Linda

doi:10.1016/j.fm.2019.103400

Cited by 18 publications

(20 citation statements)

References 27 publications

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“…Isolates recovered from finished meat products showed the highest LHR prevalence (24.5%) compared to isolates from earlier processing stages and animal feces (0 to 0.9%) ( Table 3). Similar to previous reports (11,12,(19)(20)(21)(22), the prevalences of LHR and virulence factors appear to have an inverse relationship. The majority of the LHR 1 E. coli (99.4%) in…”

Section: Resultssupporting

confidence: 88%

“…E. coli strains lacking the virulence factors associated with EHEC, STEC, and EPEC are common nonpathogens harbored by all mammals and are merely an indicator of fecal contamination. Nevertheless, LHR detection in human clinical isolates and EHEC pathogenic serogroups (20,21,23), combined with LHR-mediated transfer of heat resistance to pathogens (11,15), clearly emphasizes the likelihood that treatment-tolerant foodborne pathogenic E. coli can pose a serious public health threat.…”

Section: Resultsmentioning

confidence: 99%

“…These studies reported a lack of virulence factors in the majority of LHR 1 E. coli. On the other hand, 0.49% of human clinical E. coli isolates (n = 613) (20,21) and 2% of extended-spectrum beta-lactamase-producing E. coli isolates from hospital settings (n = 115) (22) carry the LHR with XHR phenotype. A recent study identified STEC of serogroups O26, O45, O145, and O157 that possessed the LHR and demonstrated moderate heat resistance (23).…”

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confidence: 99%

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Locus of Heat Resistance (LHR) in Meat-Borne Escherichia coli: Screening and Genetic Characterization

Guragain

Brichta-Harhay

Bono

et al. 2021

Appl Environ Microbiol

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Microbial resistance to processing treatments poses a food safety concern as treatment tolerant pathogens can emerge. Occasional foodborne outbreaks caused by pathogenic E. coli have led to human and economic losses. Therefore, this study screened for the extreme heat resistance (XHR) phenotype as well as one known genetic marker, the Locus of Heat Resistance (LHR), in 4123 E. coli isolated from diverse meat animals at different processing stages. Prevalence of XHR and LHR amongst the meat-borne E. coli was found to be 10.3% and 11.4% respectively, with 19% agreement between the two. Finished meat products showed the highest LHR prevalence (24.3%) compared to other processing stages (0-0.6%). None of the LHR+ E. coli in this study would be considered pathogens based on screening for virulence genes. Four high-quality genomes were generated by whole genome sequencing of representative LHR+ isolates. Nine horizontally acquired LHRs were identified and characterized, four plasmid-borne and five chromosomal. Nine newly identified LHRs belong to ClpK1 LHR or ClpK2 LHR variants sharing 61-68% nucleotide sequence identity, while one LHR appears to be a hybrid. Our observations suggest positive correlation between number of LHR regions present in isolates and the extent of heat resistance. The isolate exhibiting the highest degree of heat resistance possessed 4 LHRs belonging to three different variant groups. Maintenance of as many as 4 LHRs in a single genome emphasizes the benefits of the LHR in bacterial physiology and stress-response. IMPORTANCE Currently, a “multiple-hurdle” approach based on a combination of different antimicrobial interventions including heat are being utilized during meat processing to control the burden of spoilage and pathogenic bacteria. Our recent study suggests U.S. beef cattle harbor E. coli that possess the Locus of Heat Resistance (LHR). LHR seemingly contributes to the global stress tolerance in bacteria, hence poses a food safety concern. Therefore, it is important to understand the distribution of the LHR amongst meat-borne bacteria identified at different stages of different meat processing systems. Complete genome sequencing and comparative analysis of selected heat resistant bacteria provides a clearer understanding of stress and heat resistance mechanisms. Further, sequencing data may offer a platform to gain further insights into genetic background that provides optimal bacterial tolerance against heat and other processing treatments.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Locus of Heat Resistance (LHR) in Meat-Borne Escherichia coli: Screening and Genetic Characterization

Guragain

Brichta-Harhay

Bono

et al. 2021

Appl Environ Microbiol

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“…Heat resistant E. coli isolates included originated from both clinical and environmental sources; three clinical isolates previously identified as 111, 128, and 8354 were from human cases of acute gastroenteritis submitted to Alberta Precision Laboratories-Provincial Laboratory for Public Health (ProvLab) [15]. Environmental isolate AW1.7 originated from a local cattle slaughter plant [16] and isolates 53 and 63 were obtained from a municipal wastewater treatment plant [17].…”

Section: Bacterial Isolates and Growth Conditionsmentioning

confidence: 99%

“…Biofilm formation in both EHEC and heat resistant E. coli strains has not been well explored, but the presence of the organism may serve as a substantial threat to food safety [8,13]. Reports of heat resistant, clinical isolates have shown resistance to heat and osmotic stress at temperatures of 60 °C and 71 °C [14,15]. These temperatures are comparable to those used in the food processing industry's heat inactivation procedures and reflective of temperatures recommended for safe consumer cooking.…”

Section: Introductionmentioning

confidence: 99%

Phenotypic and Genetic Determination of Biofilm Formation in Heat Resistant Escherichia coli Possessing the Locus of Heat Resistance

Neumann

Chui

2021

Microorganisms

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Despite the effectiveness of thermal inactivation processes, Escherichia coli biofilms continue to be a persistent source of contamination in food processing environments. E. coli strains possessing the locus of heat resistance are a novel food safety threat and raises the question of whether these strains can also form biofilms. The objectives of this study were to determine biofilm formation in heat resistant E. coli isolates from clinical and environmental origins using an in-house, two-component apparatus and to characterize biofilm formation-associated genes in the isolates using whole genome sequencing. Optimal conditions for biofilm formation in each of the heat resistant isolates were determined by manipulating inoculum size, nutrient concentration, and temperature conditions. Biofilm formation in the heat resistant isolates was detected at temperatures of 24 °C and 37 °C but not at 4 °C. Furthermore, biofilm formation was observed in all environmental isolates but only one clinical isolate despite shared profiles in biofilm formation-associated genes encoded by the isolates from both sources. The circulation of heat resistant E. coli isolates with multi-stress tolerance capabilities in environments related to food processing signify that such strains may be a serious food safety and public health risk.

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Waterborne Bacteria Detection Based on Electrochemical Transducer

Razmi,

Willander,

Nur

2023

Sensing Technologies for Real Time Monitoring of Water Quality

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Characterization of Escherichia coli possessing the locus of heat resistance isolated from human cases of acute gastroenteritis

Cited by 18 publications

References 27 publications

Locus of Heat Resistance (LHR) in Meat-Borne Escherichia coli: Screening and Genetic Characterization

Locus of Heat Resistance (LHR) in Meat-Borne Escherichia coli: Screening and Genetic Characterization

Phenotypic and Genetic Determination of Biofilm Formation in Heat Resistant Escherichia coli Possessing the Locus of Heat Resistance

Waterborne Bacteria Detection Based on Electrochemical Transducer

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