Comparative analyses of persistence traits in O157:H7 strains belonging to different clades including REPEXH01 and REPEXH02 strains.

Recent application of whole genome sequencing in the investigation of foodborne illness outbreaks has facilitated the identification of Reoccurring, Emerging, or Persistent (REP) bacterial strains that have caused illnesses over extended periods of time. Here, the complete genomes of two O157:H7 (EcO157) outbreak strains belonging to REPEXH01 and REPEXH02, respectively, were sequenced and annotated. Comparative genomics and phenotypic analyses were carried out to identify REP-associated traits.

Conditional expression of flagellar motility, curli fimbriae, and biofilms in Shiga toxin- producing .

is an emerging foodborne pathogen. We previously reported that some avian Shiga toxin-producing strains exhibited higher or comparable cytotoxicity in Vero-d2EGFP cells with several enterohemorrhagic (EHEC) outbreak strains. To better understand the environmental persistence of this pathogen, comparative genomics and phenotypic assays were applied to assess adhesion capability, motility, and biofilm formation in .

Genomic and Phenotypic Characterization of Shiga Toxin-Producing Strains Isolated from Wild Birds in a Major Agricultural Region in California.

is an emerging foodborne pathogen. To better understand the pathogenesis and health risk of this pathogen, comparative genomics and phenotypic characterization were applied to assess the pathogenicity potential of strains isolated from wild birds in a major agricultural region in California. Shiga toxin genes were present in all avian strains.

Pathogenicity assessment of Shiga toxin-producing strains isolated from wild birds in a major agricultural region in California.

Shiga toxin-producing (STEC) consists of diverse strains differing in genetic make-up and virulence potential. To better understand the pathogenicity potential of STEC carried by the wildlife, three STEC and one strains isolated from wild birds near a major agricultural region in California were selected for comparative pathogenomic analyses. Three American crow () strains, RM9088, RM9513, and RM10410, belonging to phylogroup A with serotypes O109:H48, O9:H30, and O113:H4, respectively, and a red-winged blackbird () strain RM14516 in phylogroup D with serotype O17:H18, were examined.

Comparative genomic and phenotypic analyses of the virulence potential in Shiga toxin-producing O121:H7 and O121:H10.

Shiga toxin-producing (STEC) O121 is among the top six non-O157 serogroups that are most frequently associated with severe disease in humans. While O121:H19 is predominant, other O121 serotypes have been frequently isolated from environmental samples, but their virulence repertoire is poorly characterized. Here, we sequenced the complete genomes of two animal isolates belonging to O121:H7 and O121:H10 and performed comparative genomic analysis with O121:H19 to assess their virulence potential.

Effect of an Eco-Friendly Cuminaldehyde Guanylhydrazone Disinfectant on Shiga Toxin Production and Global Transcription of .

Antimicrobials have been important medicines used to treat various infections. However, some antibiotics increase the expression of Shiga toxin (Stx). Also, the pervasive use of persistent antibiotics has led to ecotoxicity and antibiotic resistance.

Comparative Genomics Applied to Systematically Assess Pathogenicity Potential in Shiga Toxin-Producing O145:H28.

Shiga toxin-producing (STEC) O145:H28 can cause severe disease in humans and is a predominant serotype in STEC O145 environmental isolates. Here, comparative genomics was applied to a set of clinical and environmental strains to systematically evaluate the pathogenicity potential in environmental strains. While the core genes-based tree separated all O145:H28 strains from the non O145:H28 reference strains, it failed to segregate environmental strains from the clinical.

Epigenetic regulation of gene expression in Shiga toxin-producing : Transcriptomic data.

Shiga toxin-producing (STEC) strain RM13514 is a clinical isolate linked to the 2010 romaine lettuce-associated outbreak in the U.S. The genes encoding a type II restriction and modification system, PstI R-M, are located in a prophage genome that is also encoding Shiga toxin.

DNA adenine methylase, not the PstI restriction-modification system, regulates virulence gene expression in Shiga toxin-producing Escherichia coli.

We previously reported a distinct methylome between the two Shiga toxin-producing Escherichia coli (STEC) O145:H28 strains linked to the 2010 U.S. lettuce-associated outbreak (RM13514) and the 2007 Belgium ice cream-associated outbreak (RM13516), respectively.

Differential induction of Shiga toxin in environmental Escherichia coli O145:H28 strains carrying the same genotype as the outbreak strains.

Shiga toxin-producing Escherichia coli (STEC) O145 is a major serotype associated with severe human disease. Production of Shiga toxins (Stxs), especially Stx2a, is thought to be correlated with STEC virulence. Since stx genes are located in prophages genomes, induction of prophages is required for effective Stxs production.

Genomic Insight into Natural Inactivation of Shiga Toxin 2 Production in an Environmental Strain Producing Shiga Toxin 1.

Shiga toxin-producing (STEC) consists of a group of diverse strains differing greatly in genetic make-up and pathogenicity potential. Here, we investigated production of Shiga toxins (Stxs) in a bovine isolate carrying multiple Shiga toxin genes (s) after exposure to several antibiotics commonly used in food animals. Strain RM10809-C3 was co-isolated with a STEC O145:H28 strain from cattle feces near a leafy greens-growing region in California.

Enhanced formation of shiga toxin-producing Escherichia coli persister variants in environments relevant to leafy greens production.

Bacterial persistence is a form of phenotypic heterogeneity in which a subpopulation, persisters, has high tolerance to antibiotics and other stresses. Persisters of enteric pathogens may represent the subpopulations capable of surviving harsh environments and causing human infections. Here we examined the persister populations of several shiga toxin-producing Escherichia coli (STEC) outbreak strains under conditions relevant to leafy greens production.

Curli fimbriae confer shiga toxin-producing Escherichia coli a competitive trait in mixed biofilms.

Shiga toxin-producing Escherichia coli (STEC) is one of the most common causal agents of foodborne illness linked to fresh leafy vegetables. Here, we investigated the impact of spinach-associated microorganisms on proliferation and biofilm formation of STEC O157:H7 on stainless steel surfaces at temperatures related to produce production and postharvest processing environments. Although a proliferation of inoculated pathogen cells in spinach leaf wash water was detected at all temperatures examined, the impact of spinach-associated microorganisms on the proliferation of E.

A Clonal Shiga Toxin-Producing O121:H19 Population Exhibits Diverse Carbon Utilization Patterns.

Shiga toxin-producing (STEC) serotype O121:H19 is one of the major non-O157:H7 serotypes associated with severe human disease. Here we examined population structure, virulence potential, and metabolic profile of environmental STEC O121 strains recovered from a major produce production region in California and performed comparative analyses with STEC O121 clinical isolates. Multilocus sequence typing revealed that sequence type (ST)-655, a common ST in clinical strains, was the predominant genotype among the environmental strains.

Complete Genome Sequences of Two Atypical Enteropathogenic Escherichia coli O145 Environmental Strains.

O145 strains RM14715 and RM14723 were isolated from wildlife feces near a leafy greens-growing region in Yuma, Arizona. Both strains carry a distinct genotype compared with the O145 strains isolated from Salinas Valley, California. Here we report complete genome sequences and annotations of RM14715 and RM14723.

Complete Genome Sequence of a Natural Escherichia coli O145:H11 Isolate That Belongs to Phylogroup A.

O145:H11 strain RM14721 was originally isolated from wildlife feces near a leafy greens-growing region in Yuma, AZ. This strain was initially positive for ; however, in subsequent cultures, was not detected by PCR. Here, we report the complete genome sequence and annotation of RM14721.

Survival of foodborne pathogens on commercially packed table grapes under simulated refrigerated transit conditions.

We examined the survival of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica Thompson inoculated on commercially packed table grapes under simulated refrigerated transit conditions (1.1 ± 0.5 °C; 90% RH).

Conditional Function of Autoaggregative Protein Cah and Common Mutations in Shiga Toxin-Producing Escherichia coli.

Cah is a calcium-binding autotransporter protein involved in autoaggregation and biofilm formation. Although is widespread in Shiga toxin-producing (STEC), we detected mutations in at a frequency of 31.3% in this pathogen.

Complete Genome Sequence of a Shiga Toxin-Producing Clinical Isolate.

strain M12X01451 was isolated from a patient with mild diarrhea. This strain produces a novel subtype of Shiga toxin 1, Stx1e. The Stx1e-converting prophage in strain M12X01451 is stable and can infect other bacteria following induction.

Decoding the Ecological Function of Accessory Genome.

Shiga toxin-producing Escherichia coli O157:H7 primarily resides in cattle asymptomatically, and can be transmitted to humans through food. A study by Lupolova et al. applied a machine-learning approach to complex pan-genome information and predicted that only a small subset of bovine isolates have the potential to cause diseases in humans.

Curli fimbriae are conditionally required in Escherichia coli O157:H7 for initial attachment and biofilm formation.

Several species of enteric pathogens produce curli fimbriae, which may affect their interaction with surfaces and other microbes in nonhost environments. Here we used two Escherichia coli O157:H7 outbreak strains with distinct genotypes to understand the role of curli in surface attachment and biofilm formation in several systems relevant to fresh produce production and processing. Curli significantly enhanced the initial attachment of E.

An Environmental Shiga Toxin-Producing Escherichia coli O145 Clonal Population Exhibits High-Level Phenotypic Variation That Includes Virulence Traits.

Shiga toxin-producing Escherichia coli (STEC) serotype O145 is one of the major non-O157 serotypes associated with severe human disease. Here we examined the genetic diversity, population structure, virulence potential, and antimicrobial resistance profiles of environmental O145 strains recovered from a major produce production region in California. Multilocus sequence typing analyses revealed that sequence type 78 (ST-78), a common ST in clinical strains, was the predominant genotype among the environmental strains.

Effect of sulfur dioxide fumigation on survival of foodborne pathogens on table grapes under standard storage temperature.

We examined the fate of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica Thompson inoculated on freshly-harvested table grapes under standard cold storage with initial and weekly sulfur dioxide (SO2) fumigation. L. monocytogenes and S.

Genetic diversity and virulence potential of Staphylococcus aureus isolates from raw and processed food commodities in Shanghai.

The risk of zoonotic transmission to humans highlights the need to understand the molecular ecology of Staphylococcus aureus in foods. In this study, 142 S. aureus isolates obtained from various raw and processed foods from Shanghai, China were characterized to determine their genetic diversity and virulence gene content.

Natural rpoS mutations contribute to population heterogeneity in Escherichia coli O157:H7 strains linked to the 2006 US spinach-associated outbreak.

We previously reported significantly different acid resistance between curli variants derived from the same Escherichia coli O157:H7 strain, although the curli fimbriae were not associated with this phenotypic divergence. Here we investigated the underlying molecular mechanism by examining the genes encoding the common transcriptional regulators of curli biogenesis and acid resistance. rpoS null mutations were detected in all curli-expressing variants of the 2006 spinach-associated outbreak strains, whereas a wild-type rpoS was present in all curli-deficient variants.