Jisun Haan

Campylobacter jejuni is a leading cause of foodborne gastroenteritis globally and is classified by the Centers for Disease Control and Prevention as a serious public health threat due to increasing resistance to fluoroquinolones and macrolides. This study used whole-genome sequencing to characterize the virulence and antimicrobial resistance profiles of 2,783 clinical C. jejuni isolates (98.4% stool, 1.2% unknown source, 0.4% blood, and one from rectal swab) collected from Minnesota residents from 2018 through 2021. More than 90% of the isolates had genes related to stress defense ( rpoN and htrB ), cytolethal distending toxin ( cdtA , cdtB , and cdtC ), and cell adhesion and invasion ( ciaB , cadF , and flaC ). A diverse array of antimicrobial resistance genes were detected, with beta-lactam resistance genes having a particularly high prevalence. Five gyrA point mutations associated with quinolone resistance were present in 29% of isolates, with the T861 substitution being the most prevalent. Phenotypically, tetracycline resistance was most common (52.3%), followed by quinolone resistance (30.7%), while resistance to other antimicrobial classes—macrolide (2.4%) and aminoglycoside (1.8%)—was uncommon. To evaluate the correlation between genotypic and phenotypic antimicrobial resistance profiles, the antimicrobial susceptibility testing results from a subset of isolates were compared with genotypic resistance profiles. The results showed a strong overall correlation, particularly for tetracycline and quinolones, though 24 discrepancies were detected. In the majority of discrepancies ( n = 21), genomic antimicrobial resistance markers were absent in isolates that were phenotypically resistant, suggesting possible unknown resistance mechanisms or limitations in current sequencing analysis methods. The remaining three discrepancies occurred in isolates that had the tet (O) resistance gene but were susceptible to tetracycline phenotypically. These findings highlight the value of whole-genome sequencing in improving antimicrobial resistance surveillance and understanding virulence-associated factors in C. jejuni , supporting its integration into routine monitoring practices to better manage and understand antimicrobial resistance in foodborne pathogens. IMPORTANCE: This study characterizes the virulence and antimicrobial resistance profiles of Campylobacter isolates using whole-genome sequencing (WGS) data generated through routine foodborne disease surveillance. A subset of isolates was also tested for phenotypic antimicrobial susceptibility testing, allowing us to evaluate resistance patterns and assess genotype-phenotype concordance. This comparison provides important evidence regarding the reliability and limitations of using WGS-detected resistance determinants to predict antimicrobial susceptibility. The 5 years of accumulated surveillance data provide a comprehensive, population-level understanding of circulating Campylobacter strains in Minnesota, USA, and establish an important regional baseline for monitoring changes over time. These findings can be compared with national surveillance data to identify geographic similarities and differences and provide a valuable regional context for public health decision-making and antimicrobial stewardship.

The prevalence of Salmonella enterica serovar Enteritidis encoding a GyrA D87Y substitution, associated with decreased susceptibility to ciprofloxacin, has increased since 2018 in the United States. Here, we provide three Salmonella Enteritidis reference genomes belonging to an SNP cluster of interest with ( n = 2) or without (n = 1) the GyrA D87Y substitution.

Campylobacter jejuni is a leading cause of foodborne gastroenteritis globally and is classified by the CDC as a serious public health threat due to increasing resistance to fluoroquinolones and macrolides. This study used whole-genome sequencing to characterize the virulence and antimicrobial resistance profiles of 2,783 clinical C. jejuni isolates collected from Minnesota residents from 2018 through 2021. More than 90% of the isolates had genes related to stress defense ( rpoN and htrB ), cytolethal distending toxin ( cdtA, cdtB , and cdtC ), and cell adhesion and invasion ( ciaB, cadF , and flaC ). A diverse array of antimicrobial resistance genes was detected, with beta-lactam resistance genes having a particularly high prevalence. The gyrA point mutation associated with quinolone resistance was present in 29% of isolates. To evaluate the correlation between genotypic and phenotypic antimicrobial resistance profiles, the antimicrobial susceptibility testing results from a subset of isolates were compared with genotypic resistance profiles. Results showed a strong overall correlation, particularly for tetracycline and quinolones, though 24 discrepancies were detected. In the majority of discrepancies (n=21), genomic antimicrobial resistance markers were absent in isolates that were phenotypically resistant, suggesting possible unknown resistance mechanisms or limitations in current sequencing methods. The remaining three discrepancies occurred in isolates that had the tet (O) resistance gene but were susceptible to tetracycline phenotypically. These findings highlight the value of whole genome sequencing in improving antimicrobial resistance surveillance and understanding virulence factors in C. jejuni , supporting its integration into routine monitoring practices to better manage and understand antimicrobial resistance in foodborne pathogens.

We report the complete genome of a sorbitol-fermenting, β -glucuronidase-positive, non-motile Escherichia coli O157:H7 isolated from a human stool sample. The genome consisted of a 5,487,050-bp circular chromosome and a 79,741-bp F-like plasmid.

This paper describes the hybrid genome assembly of sucrose non-fermenting non-O1/non-O139 Vibrio cholerae isolated from human soft tissue infection. The hybrid assembled genome comprises two circular chromosomes with lengths of 3,001,999 bp and 1,264,051 bp, respectively, with a G + C content of 47.38%.

Biofilms complicate treatment of Staphylococcus aureus (SA) wound infections. Previously, we determined alpha-toxin (AT)-promoted SA biofilm formation on mucosal tissue. Therefore, we evaluated SA wound isolates for AT production and biofilm formation on epithelium and assessed the role of AT in biofilm formation. Thirty-eight wound isolates were molecularly typed by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (ST), and spa typing. We measured biofilm formation of these SA isolates in vitro and ex vivo and quantified ex vivo AT production. We also investigated the effect of an anti-AT monoclonal antibody (MEDI4893*) on ex vivo biofilm formation by methicillin-resistant SA (USA 300 LAC) and tested whether purified AT rescued the biofilm defect of hla mutant SA strains. The predominant PFGE/ST combinations were USA100/ST5 (50%) and USA300/ST8 (33%) for methicillin-resistant SA (MRSA, n = 18), and USA200/ST30 (20%) for methicillin-susceptible SA (MSSA, n = 20). Ex vivo AT production correlated significantly with ex vivo SA wound isolate biofilm formation. Anti-alpha-toxin monoclonal antibody (MEDI4893*) prevented ex vivo biofilm formation by MRSA USA300 strain LAC. Wild-type AT rescued the ex vivo biofilm defect of non-AT producing SA strains. These findings provide evidence that AT plays a role in SA biofilm formation on epithelial surfaces and suggest that neutralization of AT may be useful in preventing and treating SA infections.