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Kalalah AA, Koenig SSK, Bono JL, Bosilevac JM, Eppinger M. Pathogenomes and virulence profiles of representative big six non-O157 serogroup Shiga toxin-producing Escherichia coli. Front Microbiol 2024; 15:1364026. [PMID: 38562479 PMCID: PMC10982417 DOI: 10.3389/fmicb.2024.1364026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Accepted: 02/29/2024] [Indexed: 04/04/2024] Open
Abstract
Shiga toxin (Stx)-producing Escherichia coli (STEC) of non-O157:H7 serotypes are responsible for global and widespread human food-borne disease. Among these serogroups, O26, O45, O103, O111, O121, and O145 account for the majority of clinical infections and are colloquially referred to as the "Big Six." The "Big Six" strain panel we sequenced and analyzed in this study are reference type cultures comprised of six strains representing each of the non-O157 STEC serogroups curated and distributed by the American Type Culture Collection (ATCC) as a resource to the research community under panel number ATCC MP-9. The application of long- and short-read hybrid sequencing yielded closed chromosomes and a total of 14 plasmids of diverse functions. Through high-resolution comparative phylogenomics, we cataloged the shared and strain-specific virulence and resistance gene content and established the close relationship of serogroup O26 and O103 strains featuring flagellar H-type 11. Virulence phenotyping revealed statistically significant differences in the Stx-production capabilities that we found to be correlated to the strain's individual stx-status. Among the carried Stx1a, Stx2a, and Stx2d phages, the Stx2a phage is by far the most responsive upon RecA-mediated phage mobilization, and in consequence, stx2a + isolates produced the highest-level of toxin in this panel. The availability of high-quality closed genomes for this "Big Six" reference set, including carried plasmids, along with the recorded genomic virulence profiles and Stx-production phenotypes will provide a valuable foundation to further explore the plasticity in evolutionary trajectories in these emerging non-O157 STEC lineages, which are major culprits of human food-borne disease.
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Affiliation(s)
- Anwar A. Kalalah
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
- South Texas Center for Emerging Infectious Diseases (STCEID), San Antonio, TX, United States
| | - Sara S. K. Koenig
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
- South Texas Center for Emerging Infectious Diseases (STCEID), San Antonio, TX, United States
| | - James L. Bono
- U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS), U.S. Meat Animal Research Center, Clay Center, NE, United States
| | - Joseph M. Bosilevac
- U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS), U.S. Meat Animal Research Center, Clay Center, NE, United States
| | - Mark Eppinger
- Department of Molecular Microbiology and Immunology, University of Texas at San Antonio, San Antonio, TX, United States
- South Texas Center for Emerging Infectious Diseases (STCEID), San Antonio, TX, United States
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Milani G, Belloso Daza MV, Cortimiglia C, Bassi D, Cocconcelli PS. Genome engineering of Stx1-and Stx2-converting bacteriophages unveils the virulence of the dairy isolate Escherichia coli O174:H2 strain UC4224. Front Microbiol 2023; 14:1156375. [PMID: 37426006 PMCID: PMC10326431 DOI: 10.3389/fmicb.2023.1156375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 06/06/2023] [Indexed: 07/11/2023] Open
Abstract
The past decade witnessed the emergence in Shiga toxin-producing Escherichia coli (STEC) infections linked to the consumption of unpasteurized milk and raw milk cheese. The virulence of STEC is primarily attributed to the presence of Shiga toxin genes (stx1 and stx2) carried by Stx-converting bacteriophages, along with the intimin gene eae. Most of the available information pertains to the "Top 7" serotypes associated with STEC infections. The objectives of this study were to characterize and investigate the pathogenicity potential of E. coli UC4224, a STEC O174:H2 strain isolated from semi-hard raw milk cheese and to develop surrogate strains with reduced virulence for use in food-related studies. Complete genome sequence analysis of E. coli UC4224 unveiled the presence of a Stx1a bacteriophage, a Stx2a bacteriophage, the Locus of Adhesion and Autoaggregation (LAA) pathogenicity island, plasmid-encoded virulence genes, and other colonization facilitators. In the Galleria mellonella animal model, E. coli UC4224 demonstrated high pathogenicity potential with an LD50 of 6 CFU/10 μL. Upon engineering E. coli UC4224 to generate single and double mutant derivatives by inactivating stx1a and/or stx2a genes, the LD50 increased by approximately 1 Log-dose in the single mutants and 2 Log-doses in the double mutants. However, infectivity was not completely abolished, suggesting the involvement of other virulence factors contributing to the pathogenicity of STEC O174:H2. Considering the possibility of raw milk cheese serving as a reservoir for STEC, cheesemaking model was developed to evaluate the survival of UC4224 and the adequacy of the respective mutants as reduced-virulence surrogates. All tested strains exhibited the ability to survive the curd cooking step at 48°C and multiplied (3.4 Log CFU) in cheese within the subsequent 24 h. These findings indicate that genomic engineering did not exert any unintended effect on the double stx1-stx2 mutant behaviour, making it as a suitable less-virulent surrogate for conducting studies during food processing.
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Chen T, Zhao MX, Tang XY, Wei WX, Wen X, Zhou SZ, Ma BH, Zou YD, Zhang N, Mi JD, Wang Y, Liao XD, Wu YB. The tigecycline resistance gene tetX has an expensive fitness cost based on increased outer membrane permeability and metabolic burden in Escherichia coli. JOURNAL OF HAZARDOUS MATERIALS 2023; 458:131889. [PMID: 37348375 DOI: 10.1016/j.jhazmat.2023.131889] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 05/23/2023] [Accepted: 06/16/2023] [Indexed: 06/24/2023]
Abstract
Livestock-derived tetX-positive Escherichia coli with tigecycline resistance poses a serious risk to public health. Fitness costs, antibiotic residues, and other tetracycline resistance genes (TRGs) are fundamental in determining the spread of tetX in the environment, but there is a lack of relevant studies. The results of this study showed that both tetO and tetX resulted in reduction in growth and an increased in the metabolic burden of E. coli, but the presence of doxycycline reversed this phenomenon. Moreover, the protection of E. coli growth and metabolism by tetO was superior to that of tetX in the presence of doxycycline, resulting in a much lower competitiveness of tetX-carrying E. coli than tetO-carrying E. coli. The results of RNA-seq showed that the increase in outer membrane proteins (ompC, ompF and ompT) of tetX-carrying E. coli resulted in increased membrane permeability and biofilm formation, which is an important reason for fitness costs. Overall, the increased membrane permeability and metabolic burden of E. coli is the mechanistic basis for the high fitness cost of tetX, and the spread of tetO may limit the spread of tetX. This study provides new insights into the rational use of tetracycline antibiotics to control the spread of tetX.
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Affiliation(s)
- Tao Chen
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Min-Xing Zhao
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Xiao-Yue Tang
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Wen-Xiao Wei
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Xin Wen
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Shi-Zheng Zhou
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Bao-Hua Ma
- Foshan Customs Comprehensive Technology Center, Foshan 528200, China
| | - Yong-De Zou
- Foshan Customs Comprehensive Technology Center, Foshan 528200, China
| | - Na Zhang
- Foshan Customs Comprehensive Technology Center, Foshan 528200, China
| | - Jian-Dui Mi
- State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou 730000, China
| | - Yan Wang
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou 510642, China; Maoming Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Maoming 525000, China; National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou 510642, China; State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Xin-Di Liao
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou 510642, China; Maoming Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Maoming 525000, China; National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou 510642, China; State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science, South China Agricultural University, Guangzhou 510642, China
| | - Yin-Bao Wu
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Animal Science, South China Agricultural University, Guangzhou 510642, China; Maoming Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Maoming 525000, China; National Engineering Research Center for Breeding Swine Industry, College of Animal Science, South China Agricultural University, Guangzhou 510642, China; Guangdong Provincial Key Laboratory of Agro-animal Genomics and Molecular Breeding, South China Agricultural University, Guangzhou 510642, China; State Key Laboratory of Swine and Poultry Breeding Industry, College of Animal Science, South China Agricultural University, Guangzhou 510642, China.
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Loads of Coliforms and Fecal Coliforms and Characterization of Thermotolerant Escherichia coli in Fresh Raw Milk Cheese. Foods 2022; 11:foods11030332. [PMID: 35159482 PMCID: PMC8834472 DOI: 10.3390/foods11030332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 01/17/2022] [Accepted: 01/20/2022] [Indexed: 12/15/2022] Open
Abstract
The aim of this study was to assess the hygienic status of raw milk cheese and determine the trends of virulence and antimicrobial resistance in thermotolerant Escherichia coli. Two hundred samples of karish, a popular Egyptian fresh raw milk cheese, were analyzed for coliforms and fecal coliforms using a standard most probable number (MPN) technique. Overall, 85% of samples were unsuitable for consumption, as they exceeded Egyptian standards for coliforms (10 MPN/g), and 65% of samples exhibited coliforms at 44.5 °C. Of 150 recovered thermotolerant strains, 140 (93.3%) were identified as E. coli. Importantly, one Shiga toxin-producing E. coli (STEC) strain carrying a striking virulence pattern, stx1−, stx2+, eae−, was detected. Eleven strains (7.8%, 11/140) showed resistance to third-generation cephalosporins. Antibiotic resistance genes included blaSHV, blaCTX-M, qnrS, tet(A), and tet(B), which were present in 4.3%, 2.8%, 0.71%, 2.1%, and 0.71% of isolates, respectively. In conclusion, this study indicated that hygienic-sanitary failures occurred throughout the production process of most retail karish cheese. Furthermore, our findings emphasize the need for adopting third-generation cephalosporin-resistant E. coli as an indicator for monitoring antimicrobial resistance in raw milk cheese to identify the potential public health burden associated with its consumption.
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