Shoukui He

Extended-spectrum β-lactamase genes in foodborne Salmonella enterica can disseminate through mobile multidrug-resistance platforms. IncHI2 plasmids are important resistance vehicles capable of carrying complex resistance regions and facilitating their horizontal transfer across diverse bacterial backgrounds, but the transfer and genomic organization of IncHI2 elements co-carrying bla_LAP-2 and bla_CTX-M-55 remain insufficiently characterized. This study investigated two multidrug-resistant foodborne isolates recovered in Shanghai in 2022: Salmonella Agona ST13 isolate Sal22C150 and Salmonella Havana ST1527 isolate Sal22P208. Antimicrobial susceptibility testing, whole-genome sequencing, conjugation, plasmid-retention analysis, comparative genomics, as well as strain- and plasmid-level phylogenetic analyses were performed. Both isolates exhibited broad antimicrobial resistance, including resistance to extended-spectrum cephalosporins. In both isolates, bla_LAP-2 and bla_CTX-M-55 co-transferred with the IncHI2 replicon to Escherichia coli J53 at frequencies of (4.95 ± 0.41) × 10⁻⁵ and (4.46 ± 0.42) × 10⁻⁶ transconjugants per donor cell, respectively. All tested plasmid markers remained detectable through 20 passages without antimicrobial selection. Complete assembly of Sal22P208 confirmed the location of the three β-lactamase genes on the 275,096 bp IncHI2 plasmid pSal22P208. The plasmid contained a conserved conjugative backbone and mosaic accessory regions carrying 15 antimicrobial-resistance determinants together with mercury- and tellurium-resistance loci. SNP-based analysis placed pSal22P208 within a closely related cluster containing six reference IncHI2 plasmids differing by fewer than 30 SNPs and recovered from Salmonella and E. coli of animal, food, and human origin, suggesting a broad distribution of this plasmid lineage across diverse bacterial and ecological backgrounds. Sal22P208 additionally contained a Tn3-associated chromosomal multidrug-resistance region between rpmJ and rpmE that shared extensive structural similarity with a region in Citrobacter braakii LBA3. These findings highlight the role of transferable IncHI2 resistance platforms in the horizontal dissemination and short-term post-transfer maintenance of linked resistance determinants, while chromosomally integrated resistance regions may provide an additional route for the accumulation and inheritance of multidrug resistance in foodborne Salmonella.

Malassezia furfur (M. furfur), a lipophilic yeast, is recognized as the main cause of prevalent human scalp diseases including dandruff.[1] Conventional antifungal agents such as zinc pyrithione, s...

Eugenol, a major bioactive compound present in various essential oils with substantial antibacterial activity, has limited application in food industries due to its low water solubility. To address this limitation, a microemulsion system was developed utilizing Tween 80 as a surfactant and lactic acid as a co‐surfactant to facilitate the delivery of eugenol. The resulting microemulsion underwent physicochemical characterization, antibacterial evaluation, and sanitation trials on fresh‐cut lettuce. Phase analysis revealed three distinct types of microemulsions with stability and dispersibility: water‐in‐oil with 0%–20% water, bicontinuous with 30%–60% water, and oil‐in‐water with 70%–90% water. Antibacterial assays indicated minimum inhibitory concentrations of 0.5 mg/mL for Staphylococcus aureus and 0.25 mg/mL for Escherichia coli , along with minimum bactericidal concentrations of 1 and 0.5 mg/mL, respectively. Furthermore, the microemulsion at 1 mg/mL exhibited rapid bactericidal effects against both bacterial strains, achieving a population reduction of over 6‐log units within 10 min. In refrigerated fresh‐cut lettuce sanitation experiments, microemulsion concentrations of 0.25, 0.5, and 1 mg/mL effectively suppressed the number of total microbes, mold, and yeast, with 0.5 mg/mL treatment being most effective in maintaining lettuce quality and freshness. Additionally, these treatments contributed to the preservation of vitamin C content, chlorophyll level, and color stability. Overall, the results demonstrate that eugenol microemulsions hold strong potential as green sanitizers for vegetables, offering a promising avenue to enhance food safety and quality.

This study investigates and compares Food Safety Management System (FSMS) compliance in retail shops across Mazovia (Poland) and Kerala (India). A structured visual inspection checklist with 51 indicators across seven FSMS sections was used in 500 shops per country: design and layout, general food safety, food handling and storing practices, display, personnel hygiene practices, sanitation and cleanliness, and pest control. Each section was scored using a four-point ordinal scale. Compliance scores were analyzed using the Mann-Whitney U test, Kruskal–Wallis test, Principal Component Analysis (PCA), and Cluster analysis to identify influencing factors and compliance patterns. The results demonstrate significant differences between the two countries, with Polish retail shops showing notably higher compliance (p < 0.001). No significant difference was observed in the design and layout section (p = 0.103). None of the assessed shop categories in either country achieved full compliance with all food safety requirements. Retail format, location, and number of employees were significantly associated with compliance levels. This is the first comparative study to examine FSMS compliance in retail shops in Mazovia, Poland, and Kerala, India, using a standardized visual inspection method. The findings contribute to a better understanding of FSMS performance in retail environments under different economic and regulatory conditions. Identifying how variations in retail format, staffing, and operational practices influence FSMS compliance can support the development of context-specific strategies to improve food safety performance.

Ensuring food safety while advancing sustainability is increasingly recognised as a dual imperative for modern food systems. However, the interconnection between food safety and sustainability at the retail and food service levels remains underexplored. This study is aimed at assessing and comparing the prevailing food safety practices (FSP) and sustainability practices (SUST) among grocerants, which are hybrid outlets combining grocery retail and restaurant functions, in Ghana, Poland, and India. A structured 28‐indicator observational checklist (14 FSP and 14 SUST indicators) was applied during unannounced audits of 150 grocerants. The analysis revealed significant cross‐country differences in compliance levels for both sections. Polish grocerants achieved comparatively the highest mean scores, reflecting advanced hygiene management and proactive SUST, whereas Ghanaian and Indian outlets exhibited moderate compliance. Cluster analysis identified three groups representing low‐, transitional‐, and high‐maturity stages of sustainable food safety performance. Grocerants with stronger food safety compliance also demonstrated higher sustainability engagement, suggesting an association between the two domains. The findings highlight differences in regulatory enforcement and managerial commitment across various contexts, contributing to the development of the concept of sustainable food safety management, which links hygiene compliance with environmental and social responsibility in emerging retail formats.

Objective: To determine the molecular characteristics and mechanisms of colistin-resistant (COLr) Salmonella isolates from 1224 chicken samples in Shanghai, China, between January 2021 and January 2022. Methods: Antimicrobial susceptibility testing, site-directed mutagenesis, RT-qPCR, and lipid A analysis was conducted to investigate the mechanisms of colistin resistance in Salmonella. Results: A total of 268 Salmonella isolates were obtained from chicken samples and 41 isolates were resistant to colistin. The uncommon extensively antimicrobial-resistant Salmonella Muenster was the predominant serotype, accounting for 87.8% (36/41) of the COLr isolates. Most (95.1%, 39/41) of the COLr isolates exhibited amino acid substitutions in the PmrAB. Ten different substitutions in PmrAB were identified, with Val161Gly (n = 14) and Gly206Glu (n = 10) in PmrB being the most prevalent. Four substitutions (Thr147Ser, Phe203Ser, Gly206Glu, and Asp250Tyr) in PmrB have not been reported before and were considered novel mutations. Additionally, it was demonstrated that these substitutions upregulated pmrE and pmrK expression, resulting in the production of L-Ara4N, which modified the lipid A and resulted in an 8–64-fold increase in the colistin MIC (2–8 mg/L). Finally, the deletion of pmrE or pmrK in mutants showed MIC values comparable to parental strains (0.25 mg/L), which suggested that colistin resistance may be conferred through the pmrE and pmrK pathways. Conclusions: These findings illustrate the complex molecular mechanisms of colistin resistance in Salmonella, and the amino acid substitutions in PmrAB are the predominant molecular mechanisms. It is essential to implement monitoring and control measures for colistin resistance.

Two-component systems (TCS) of Salmonella enterica serovar Enteritidis are composed of a histidine kinase and a response regulator (RR) and represent a critical mechanism by which bacteria develop resistance to environmental stress. Here, we characterized the functions of RRs in TCS in the formation of stress tolerance, motility and biofilm using twenty-six S. Enteritidis RR-encoding gene deletion mutants. The viability results unraveled their essential roles in resistance to elevated temperature (GlrR), pH alterations (GlrR, TctD, YedW, ArcA and YehT), high salt (PhoB, BaeR, CpxR, PhoP, UvrY and TctD), oxidative stress (PhoB, YedW, BaeR, ArcA, PhoP, UvrY, PgtA and QseB) and motility (ArcA, GlnG, PgtA, PhoB, UhpA, OmpR, UvrY and QseB) of S. Enteritidis. The results of the crystal violet staining, microscopy observation and Congo red binding assays demonstrated that the absence of ArcA, GlnG, PhoP, OmpR, ZraR or SsrB in S. Enteritidis led to a reduction in biofilms and an impairment in red/dry/rough macrocolony formation, whereas the absence of UvrY exhibited an increase in biofilms and formed a brown/smooth/sticky macrocolony. The results indicated the regulatory effects of these RRs on the production of biofilm matrix, curli fimbriae and cellulose. Our findings yielded insights into the role of TCSs, making them a promising target for combating S. Enteritidis.