Plant-Derived Phenolic Acids Limit the Pathogenesis of Salmonella Typhimurium and Protect Intestinal Epithelial Cells during Their Interactions.

The incidence of gastrointestinal illness attributable to Salmonella enterica serovar Typhimurium (ST) remains a concern for public health worldwide, as it can progress into systemic infections mediated by the type-three secretion system (T3SS), which allows for adherence and invasion to intestinal epithelial cells. The current study evaluates the ability of gallic acid (GA), protocatechuic acid (PA), and vanillic acid (VA) to impair the adhesion and invasion abilities of ST to a human epithelial (INT-407) cell monolayer while also assessing their cytotoxicity. GA, PA, and VA inhibited detectable ST growth at specific concentrations but showed cytotoxicity against INT-407 cells (>20% reduction in viability) after 3 h of treatments. Adjusting the pH of the solutions had a neutralizing effect on cytotoxicity, though it did reduce their antimicrobial potency. Adhesion of ST was reduced significantly when the cells were treated with 4.0 mg/mL of VA, whereas invasion was reduced in all treatments, with GA requiring the lowest concentration (0.5 mg/mL). Relative gene expression of virulence genes after treatment with GA showed downregulation in the T3SS regulator and effector hilA and sipA, respectively. These findings suggest further use of phenolic acids in reducing the activity of key virulence factors critical during ST infection.

Prospective Evaluation of Circulating Tumor DNA using Next Generation Sequencing as a Biomarker during Neoadjuvant Chemotherapy in Localized Pancreatic Cancer.

OBJECTIVE: In this prospective study, we aim to characterize the prognostic value of circulating tumor DNA (ctDNA) by next-generation-sequencing (NGS) in patients undergoing neoadjuvant chemotherapy (NAC) for pancreatic ductal adenocarcinoma (PDAC). SUMMARY BACKGROUND DATA: Circulating tumor DNA is a promising blood-based biomarker that is prognostic in several malignancies. Detection of ctDNA by NGS may provide insights regarding the mutational profiles in PDAC to help guide clinical decisions for patients in a potentially curative setting. However, the utility of ctDNA as a biomarker in localized PDAC remains unclear. METHODS: Patients with localized PDAC were enrolled in a prospective study at Northwestern Medicine between October 2020 and October 2022. Blood samples were collected to perform targeted tumor agnostic NGS utilizing the Tempus x|F 105 gene panel at three timepoints: pre-therapy (at diagnosis), post-NAC, and after local therapy, including surgery. The relationship between ctDNA detection and CA19-9, and the prognostic significance of ctDNA detection were analyzed. RESULTS: 56 patients were included in the analysis. ctDNA was detectable in 48% at diagnosis, 33% post-NAC, and 41% after local therapy. After completion of NAC, patients with detectable ctDNA had higher CA19-9 levels versus those without (78.4 vs. 30.0, P=0.02). The presence of baseline ctDNA was associated with a CA19-9 response; those without ctDNA had a significant CA19-9 response following NAC (109.0 U/mL vs. 31.5 U/mL; P=0.01), while those with ctDNA present at diagnosis did not (198.1 U/mL vs. 113.8 U/mL; P=0.77). In patients treated with NAC, the presence of KRAS ctDNA at diagnosis was associated with and independently predicted worse progression-free-survival. CONCLUSION: This report demonstrates the prognostic value of ctDNA analysis with NGS in localized PDAC. NGS ctDNA is a biomarker of treatment response to NAC. KRAS ctDNA at diagnosis independently predicts worse survival in patients treated with NAC.

Assessment of the prevalence, serotype, and antibiotic resistance pattern of Salmonella enterica in integrated farming systems in the Maryland-DC area.

Implementation of organic/pasture farming practices has been increasing in the USA regardless of official certification. These practices have created an increasingly growing demand for marketing safe products which are produced through these systems. Products from these farming systems have been reported to be at greater risk of transmitting foodborne pathogens because of current trends in their practices. Salmonella enterica (SE) is a ubiquitous foodborne pathogen that remains a public health issue given its prevalence in various food products, but also in the environment and as part of the microbial flora of many domestic animals. Monitoring antibiotic resistance and identifying potential sources contamination are increasingly important given the growing trend of organic/pasture markets. This study aimed to quantify prevalence of SE at the pre- and post-harvest levels of various integrated farms and sites in Maryland-Washington D.C. area, as well as identify the most prevalent serovars and antibiotic resistance patterns. Samples from various elements within the farm environment were collected and screened for SE through culture and molecular techniques, which served to identify and serotype SE, using species and serovar-specific primers, while antibiotic resistance was evaluated using an antibiogram assay. Results showed a prevalence of 7.80% of SE pre-harvest and 1.91% post-harvest. These results also showed the main sources of contamination to be soil (2.17%), grass (1.28%), feces (1.42%) and unprocessed produce (1.48%). The most commonly identified serovar was Typhimurium (11.32%) at the pre-harvest level, while the only identified serovar from post-harvest samples was Montevideo (4.35%). With respect to antibiotic resistance, out of the 13 clinically relevant antibiotics tested, gentamycin and kanamycin were the most effective, demonstrating 78.93 and 76.40% of isolates, respectively, to be susceptible. However, ampicillin, amoxicillin and cephradine had the lowest number of susceptible isolates with them being 10.95, 12.36, and 9.83%, respectively. These results help inform farms striving to implement organic practices on how to produce safer products by recognizing areas that pose greater risks as potential sources of contamination, in addition to identifying serotypes of interest, while also showcasing the current state of antibiotic efficacy and how this can influence antibiotic resistance trends in the future.

Purified Plant-Derived Phenolic Acids Inhibit Salmonella Typhimurium without Alteration of Microbiota in a Simulated Chicken Cecum Condition.

Salmonella enterica serovar Typhimurium (ST) remains a predominant zoonotic pathogen because of its colonization in poultry, survivability in the environment, and increasing antibiotic-resistance pattern. Plant-derived phenolics, gallic acid (GA), protocatechuic acid (PA), and vanillic acids (VA) have demonstrated antimicrobial activity in vitro; therefore, this study collected chicken cecal fluid and supplemented it with these phenolics to evaluate their potential for eliminating ST and mod-ulating the microbiota of complex environments. ST was quantified through plating, while micro-biome analysis was performed through pair-end 16S-rRNA gene sequencing. CFU/mL of ST in cecal fluid with GA was significantly reduced by 3.28 and 2.78 log at 24 h and 48 h, while PA only had a slight numerical decrease. VA significantly reduced ST by 4.81 and 5.20 log at 24 h and 48 h. Changes in relative abundance of major phyla were observed at 24 h for samples with GA and VA as Firmicute levels increased 8.30% and 20.90%, while Proteobacteria decreased 12.86% and 18.48%, respectively. Significant changes in major genre were observed in Acinetobacter (3.41% for GA) and Escherichia (13.53% for VA), while Bifidobacterium increased (3.44% for GA) and Lactobacillus remained unchanged. Results suggest that phenolic compounds exert different effects on certain pathogens, while supporting some commensal bacteria.

Diarrheagenic Escherichia coli and Their Antibiotic Resistance Patterns in Dairy Farms and Their Microbial Ecosystems.

Ruminants are the largest reservoir for all types of Escherichia coli, including the pathogenic ones, which can potentially be transmitted to humans via the food chain and environment. A longitudinal study was performed to estimate the prevalence and antibiotic-resistant pattern of pathogenic E. coli (pE.coli) strains in dairy farm environments. A total of 846 environmental samples (water, lagoon slurry, bedding, feed, feces, soil, and compost) were collected in summer over two years from five dairy farms in Maryland, USA. An additional 40 soil samples were collected in winter and summer seasons for evaluating microbiome composition. Collected environmental samples were screened for the presence of pE.coli, which was isolated using a selective culture medium, for later confirmation and virotyping using PCR with specific primers. The overall prevalence of pE.coli in dairy farms was 8.93% (71/846), with the most common virotype identified in isolates being ETEC, followed by STEC. The highest pE.coli prevalence were recorded in lagoon slurry (21.57%) while the lowest was in compost heap (2.99%). Among isolates, 95.87% of the virotypes were resistant to 9 classes of antibiotics whereas only 4.12% were sensitive. The highest proportion (68.04%) of resistance was found for quinolones (e.g., ciprofloxacin). The resulting metagenomic analysis at the phylum and genus levels of the grazing land soil suggests that climatic conditions actively influence the abundance of bacteria. Proteobacteria, which contains many Gram-negative foodborne pathogens (including pE.coli), was the most predominant phylum, accounting for 26.70% and 24.93% of soil bacteria in summer and winter, respectively. In addition to relative abundance, there was no significant difference in species diversity between seasons when calculated via Simpson (D) and Shannon (H) index. This study suggests that antibiotic-resistant E. coli virotypes are present in the dairy farm environment, and proper steps are warranted to control its transmission irrespective of seasonality.

A UGT1A1 genotype-guided dosing study of modified FOLFIRINOX in previously untreated patients with advanced gastrointestinal malignancies.

BACKGROUND: FOLFIRINOX (5-fluorouracil [5-FU], leucovorin, irinotecan, oxaliplatin) is an effective but toxic therapy for pancreatic cancer. UGT1A1 (UDP glucuronosyltransferase 1A1) eliminates the active metabolite of irinotecan. Polymorphisms reduce UGT1A1 activity, leading to toxicity. The primary objective was to determine the dose-limiting toxicity (DLT) rate in cycle 1 of modified FOLFIRINOX (mFOLFIRINOX) using genotype-guided dosing of irinotecan for the most common UGT1A1 genotypes (*1/*1, *1/*28) in advanced gastrointestinal malignancies, with expansion in pancreatic and biliary tract cancers. METHOD: 5-FU (2400 mg/m2 over 46 hours), leucovorin (400 mg/m2 ), oxaliplatin (85 mg/m2 ), and irinotecan were given every 14 days. Irinotecan doses of 180, 135, and 90 mg/m2 were administered for UGT1A1 genotypes *1/*1, *1/*28, and *28/*28, respectively. Prophylactic pegfilgrastim was omitted in cycle 1 for cohort 1 (tolerability by genotype), but was given in cohort 2 (tolerability by tumor type). Doses were tolerable if the upper limit of a 2-sided 80% confidence interval for DLT rate was ≤33%. RESULTS: In cohort 1, DLTs (most commonly febrile neutropenia, fatigue, diarrhea) occurred in 2/15 (13%), 3/16 (19%), and 4/10 (40%) patients with *1/*1, *1/*28, and *28/*28 genotypes, respectively. In cohort 2, 6/19 (32%) pancreatic and 4/19 (21%) biliary tract cancer patients experienced DLTs (most commonly fatigue, diarrhea, nausea/vomiting). In cohort 2, upper confidence limits of DLT rates exceeded 33%. Response rates were 38% in pancreatic and 21% in biliary tract cancers. CONCLUSION: On the basis of our prespecified criteria, tolerability of UGT1A1 genotype-guided mFOLFIRINOX was not established in pancreatic and biliary tract cancers. However, this regimen was effective.