Biology subjects

Eppinger, M.

Publications and source records attributed to Eppinger, M..

3 recordsLinked to original sources

bioRxiv2026

Cross-Serogroup Analysis of Representative Top-Seven Shiga toxin-producing Escherichia coli Plasmids Reveals Lineage-Specific Patterns

Plasmids play a significant role in shaping the pathogenic potential of Shiga toxin-producing Escherichia coli (STEC) by encoding virulence and adaptive genes that complement chromosomal determinants. While plasmid-encoded factors such as ehxA, espP, katP, and toxB are known to enhance intestinal colonization and host interaction, the diversity and evolutionary patterns of STEC plasmids remain insufficiently characterized. Most previous studies have focused on single serogroups, particularly O157, leaving cross-serogroup comparisons largely unexplored. To address this gap, we conducted an in-depth investigation of 109 complete plasmid sequences (1.5-187 kb) from the "Top Seven" STEC serogroups (O26, O45, O103, O111, O121, O145, and O157), retrieved from NCBI, to examine their structural organization, virulence composition, resistance patterns, mobility potential, and evolutionary dynamics. Our analysis revealed the dominance of F-type plasmids carrying IncFIB and IncFII replicons across serogroups, along with lineage-specific associations with major virulence genes. By examining the enterohemolysin operon across ehxA-positive plasmids, we identified a highly conserved structural framework maintained across 92.5% of analyzed sequences, with minimal variation. We further characterized antimicrobial resistance gene distribution, finding that only 11% of plasmids (12/109) carried such genes, of which 92% were multidrug-resistant. Analysis of mobility features revealed that predicted conjugative potential and MOBF-type relaxases varied considerably among serogroups. The 32 plasmids without virulence or resistance cargo carried at most colicin determinants, yet all received a predicted mobility class, with conjugative machinery confined to plasmids above 37 kb. At the plasmid level, serogroups O26/O103 are closely related and carry relatively high-risk virulence profiles, while the O121/O145 group exhibits moderate virulence gene inventories. The O45/O111 group is further distinguished by its transfer features, while O157 strains form a distinct clade with the broadest array of plasmid-encoded high-risk virulence genes.

microbiology↗

bioRxiv2026

Pathogenome and Plasmid-Borne Antimicrobial Resistance Phenotypes in a Multidrug-Resistant O111:H8 Shiga Toxin-Producing Escherichia coli Strain

Plasmids contribute to virulence and antimicrobial resistance in Shiga toxin-producing Escherichia coli (STEC). Here, the mobility, gene content, and evolutionary context of four plasmids carried by an O111:H8 STEC strain designated UTAK-22: pUTAK-22.1-MDR, pUTAK-22.2-MDR, pUTAK-22.3-P1, and pUTAK-22.4-pO111 were characterized. Conjugation experiments, phenotype-based selective readouts, and comparative genomics together showed that pUTAK-22.1-MDR is self-transmissible, whereas pUTAK-22.2-MDR and pUTAK-22.4-pO111 are most consistent with mobilization in trans, making use of the strain's native helper plasmid background, while pUTAK-22.3-P1 represents a conjugation-deficient IncY phage-derived replicon. Genome annotation and comparative analyses further highlighted the structural diversity and mosaic composition of these plasmids, including P1-like phage remnants, virulence loci, and distinct antimicrobial resistance modules. Phenotypic profiling of the native wild-type plasmid complement and selected transconjugants in the recipient E. coli strain WG5 further showed that the presence of co-resident plasmids and redundant resistance determinants results in dosage-dependent streptomycin tolerance. Together, these findings expand our understanding of the mobility landscape, evolutionary dynamics, and resistance potential of STEC plasmids, while underscoring the importance of interpreting resistance phenotypes in the context of a strain's natural plasmid composition.

microbiology↗

bioRxiv2025

Phylogenomic framework and virulence gene boundaries of emerging Shiga toxin producing Escherichia coli O118 informed by the comprehensive profiling of 359 O118 genomes

Non-O157 Shiga toxin-producing Escherichia coli (STEC), particularly the O118 serogroup, are emerging pathogens linked to severe foodborne illnesses, including hemolytic uremic syndrome. The hallmark of STEC virulence is the production of a potent phage-borne cytotoxin, often accompanied by the locus of enterocyte effacement (LEE). This study explores the genomic landscape, virulence factors, and resistance traits of O118 STEC. We analyzed 357 publicly available O118 genomes across ten H-antigens and included two clinically significant O118:H16 STEC strains sequenced to closure. Pangenome assessment and core genome multilocus sequence typing (MLST) based on 4,160 shared genes revealed phylogenetic clustering by H-type and delineated distinct STEC-phylogroups, alongside relationships to non-STEC pathovars such as uropathogenic E. coli (UPEC), enteropathogenic E. coli (EPEC), and enterotoxigenic E. coli (ETEC). Identified STEC phylogroups encompassed H6, H12, H16, and H2 strains with diverse Shiga toxin (stx) profiles (stx1a, stx2a, stx2b, stx2c, stx2f). A subset of H2-STEC lacked stx, suggesting potential secondary phage loss. Most STEC groups harbored the locus of enterocyte effacement (LEE). Further, a strong correlation was observed between H-antigens and eae subtypes, with specific pairings such as H6/eae-{iota}, H16/eae-{beta}, and H2/eae-{varepsilon}. Horizontally acquired pathogenicity islands--including O-island 122 in H16 strains and a novel pathogenicity-associated island carrying antibiotic resistance--along with other loci related to colonization and interbacterial competition, further enhance these strains virulence potential. Our findings underscore the genetic diversity and virulence potential of O118 STEC. Understanding phylogroup-specific traits and resistance markers is crucial for effective surveillance and public health interventions. ImportanceShiga toxin-producing Escherichia coli (STEC) are a major public health concern, responsible for illnesses ranging from diarrhea to life-threatening kidney damage. Among non-O157 STEC, serogroup O118 is increasingly recognized as an emerging STEC lineage. This study provides the most comprehensive genomic analysis to date of O118 STEC, offering critical insights into their pathogenome, virulence traits, and antimicrobial resistance inventories. Notably, we identified a novel 74 kb pathogenicity island in clinical strain H16-12089 that encodes a combination of multidrug resistance genes, virulence factors, and interbacterial competition systems. Understanding the genetic makeup and virulence potential of these pathogens is essential for improving surveillance, risk assessment, and public health interventions.

genomics↗