Foodborne pathogens and disease最新文献

Staphylococcus aureus (S. aureus) is a major zoonotic pathogen. To investigate CRISPR carriage in S. aureus isolates from cows with mastitis and the role of the CRISPR system and efflux pumps in antibiotic resistance. We analyzed antibiotic resistance genes and CRISPR loci, sequenced spacers, and assessed correlations between CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) presence and antibiotic resistance in 234 S. aureus isolates. The changes in CRISPR sequences were examined by continuous passage of 360 generations without antibiotic pressure. Subsequently, variations in CRISPR loci and transcript levels were measured under ciprofloxacin (CIP) exposure. In addition, an S. aureus-25-mepA was constructed to evaluate changes in antimicrobial sensitivity and mepA transcript levels in both planktonic and biofilm states. Our results revealed a CRISPR loci detection rate of 7.69% among the 234 S. aureus isolates, with significantly lower rates of the antibiotic resistance genes gyrA, grlA, norA, and tet(M) in CRISPR-positive isolates compared to those in CRISPR-negative isolates (p < 0.05). CIP-resistant strains exhibited loss of repeat and spacer sequence in CRISPR loci, and the transcript abundance of these loci gradually decreased under CIP pressures, indicating that CRISPR loci deletion or transcript level downregulation under antibiotic stress may be a potential regulatory mechanism of antibiotic resistance. Correlation analysis linked CIP resistance in both planktonic and biofilm S. aureus to mepA transcript levels and biofilm integrity. Our study provides insight into the mechanism by which S. aureus develops antibiotic resistance via the CRISPR system and the MepA efflux pump, offering a theoretical foundation for monitoring the prevalence and resistance of pathogenic bacteria.

Listeria monocytogenes (L. monocytogenes) is an important foodborne pathogen. In this study, 41 sporadic listeriosis cases were collected during 2016-2022, including 92.7% of invasive cases and 56.1% of pregnancy-associated cases. The age of cases ranged from 0 days to 88 years, with the majority occurring in individuals aged 20 to <30 years. Serotype 1/2 b was most prevalent among 43 L. monocytogenes isolates, followed by 1/2 a, 4 b, and 3a. Sixteen clonal complexes (CCs) were determined. CC87 occupied the top slot. Genome sequencing-based phylogeny results indicated that Chinese CC1, CC8, and CC87 isolates mostly clustered in clades separating from isolates from other countries. Meanwhile, a few Chinese isolates participated in cocirculating CC1, CC8, and CC87 in Asia, Europe, Africa, South America, North America, and Oceania. All isolates harbored LIPI-1 while LIPI-2 was absent. LIPI-3 and LIPI-4 exhibited an apparent relationship with lineage and CCs. It was notably that CC4, CC224, and CC619 carried both LIPI-3 and LIPI-4. inlB, inlC, inlH, inlK, ipeA, srtA, dltA, lap, ami, fbpA, stp, oatA, intA, prsA2, lgt, hpt, iplA1, bsh, mdrT, mdrM, and brtA existed in all isolates. The percentages of inlA, inlF, inlJ, aut, vip were 97.7%, 97.7%, 97.7%, 83.7%, and 83.7%. A premature stop codon mutation of position 1474(C→T) was detected, resulting in a truncated InlA with 491 aa. High susceptibility to penicillin (100%), ampicillin (100%), gentamicin (100%), erythromycin (100%), daptomycin (100%), meropenem (100%), trimethoprim-sulfamethoxazole (100%), vancomycin (97.7%), tetacycline (97.7%), chloramphenicol (97.7%), and ciprofloxacin (90.7%) was demonstrated. lin and fosX were present in 93.0% of the isolates, respectively. tetM and ermB were also detected. This comprehensive study enriched the understanding of listeriosis cases and diversity of clinical isolates, meanwhile, indicated the spread characteristics of CC1, CC8, and CC87 in China based on phylogeny analysis, providing fundamental data for developing targeting food safety interventions to prevent listeriosis.

Campylobacter is a widespread foodborne pathogen that causes significant contamination across various samples. Rapid and accurate detection of Campylobacter enables timely diagnosis and assessment of contamination, helping to control the spread of the pathogen and ensure food safety. However, the heterogeneity of sample matrices and variability in contamination levels throughout the food supply chain pose substantial challenges to the efficient detection of Campylobacter. In this study, the conventional culture method was improved through the optimization of antibiotic combinations, the A6, A4, and A3 media achieved the highest detection concordance for low (99.04%), medium (98.69%), and high (99.29%) cleanliness samples, respectively. These media also yielded colony recovery counts equivalent to those obtained from antibiotic-free medium, making them suitable for application across the entire chain. The detection sensitivity, specificity, and accuracy of alternative molecular and immunological methods were subsequently evaluated using the optimized culture method for validation. Nucleic acid-based methods generally exhibited high sensitivity (0.98-1.00) and were suitable for use in the upstream and midstream stages, facilitating rapid exclusion of negative samples. Multiplex polymerase chain reaction (PCR) showed good accuracy (0.95-0.98) and allowed identification of contaminating bacteria at the species level, while integration with qPCR facilitated rapid assessment of contamination status of the matrices. Loop-mediated isothermal amplification and colloidal gold immunochromatographic assay offered on-site visualization of results with short detection times and operational simplicity. They also exhibited good accuracy for samples of medium cleanliness (0.80-0.97), making them well-suited to terminal retail applications. Collectively, this study compared and analyzed the applicability of culture-based, nucleic acid-based, and immunological detection methods for samples of varying cleanliness, proposing a comprehensive monitoring strategy to facilitate efficient and accurate detection of Campylobacter in the food supply chain.

Proteus mirabilis is a significant foodborne pathogen that can be transmitted through the poultry slaughter and processing chain, posing a potential threat to human health. This study aimed to assess the prevalence, antibiotic resistance, contamination potential, and presence of key virulence factors in Proteus mirabilis isolates from poultry slaughterhouses in Xinjiang. A total of 845 samples were collected during poultry slaughtering and processing, from which 95 strains of Proteus mirabilis were isolated and identified, yielding an overall detection rate of 11.24% (95/845). Analysis of interspecies differences revealed that the detection rate of chicken-derived Proteus mirabilis was significantly higher than that of pigeon-derived isolates. Antibiotic susceptibility testing showed the highest resistance rates to tetracycline (87.37%, 83/95), followed by sulfisoxazole (72.63%, 69/95). The proportion of drug-resistant strains was significantly greater in chicken-derived isolates (82.05%, 32/39) compared with pigeon-derived isolates (32.14%, 18/56). Swarming ability assays indicated that 85.26% (81/95) of the strains exhibited swarming ability, with 64.20% (52/81) demonstrating strong swarming ability, suggesting a higher risk of transmission along with the slaughter and processing chain. Additionally, 39 chicken-derived isolates with strong antibiotic resistance were selected for biofilm formation assays; all were capable of biofilm production, with 66.67% (26/39) classified as strong biofilm producers. Detection of antibiotic resistance genes revealed significantly higher prevalence of aac, aad, sul1, and sul2 genes in chicken-derived isolates compared with pigeon-derived isolates (p < 0.0001). Virulence gene map shows that all isolates carried the core virulence genes ureC and hmpA, with chicken-derived isolates generally harboring a greater number of virulence genes than pigeon-derived isolates. These findings highlight the high prevalence, strong contamination potential, and elevated pathogenic risk associated with chicken-derived Proteus mirabilis, underscoring the need to optimize hygiene management in poultry slaughterhouses, enhance monitoring of antibiotic usage, and develop targeted pathogen control strategies.

Porphyra tenera (PT), an edible red alga, is consumed as a health-promoting seaweed. Human norovirus (HuNV), the major cause of foodborne disease outbreaks worldwide, binds to histo-blood group antigens (HBGAs) for cell entry. We investigated the inhibitory activity of fucose-containing polysaccharides in PT on HuNV binding to the HBGAs. With saliva as a source of HBGAs and recombinant P domains of HuNV GII.4 and GII.17 purified as NV antigens, the inhibition and binding affinity of PT toward P domains were evaluated using enzyme-linked immunosorbent assay and bio-layer interferometry, respectively. The PT polysaccharide extract and its 3-10 kDa fraction (F3-10) among molecular weight fractions inhibited the P domain binding to saliva significantly, compared with that of a commercial fucoidan. F3-10 bound directly to the P domains with submicromolar affinities (K_D = 5.6 × 10^-7 M for GII.4 and 8.7 × 10^-7 M for GII.17). When applied to virus inhibition assays, F3-10 significantly reduced murine NV titers in a dose-dependent manner; specifically, it showed a 1.8 log₁₀ plaque forming unit (PFU)/mL reduction at 1 mg/mL in RAW 264.7 cells (p < 0.05) and a 1.4 log₁₀ PFU/mL reduction at 5 mg/mL under simulated human digestion conditions involving sequential incubation in simulated saliva, gastric, and intestinal fluids (p < 0.01). F3-10 contained galactose, glucose, fucose, and xylose as its constituent monosaccharides and also sulfate groups. The PT fraction F3-10 is a promising candidate for further study aimed at inhibiting HuNV binding to host cell HBGAs.

To characterize molecular profiles of Salmonella isolates from the Meishan region (2014-2024) via whole-genome sequencing, focusing on serotype distribution, antimicrobial resistance genes (ARGs), virulence genes, and genetic differentiation based on coding-region single nucleotide polymorphisms (cgSNPs), and provide a molecular epidemiological basis for precise prevention, control, and source tracing of Salmonella infections. Sixty Salmonella strains from distinct sources (food surveillance = 2, food poisoning = 7, intestinal surveillance = 23, pathogen surveillance = 17, healthy population surveillance = 2, and other surveillance = 9) (2014-2024), Table 1, were sequenced on Illumina NextSeq 500. Serotypes (SISTR v1.1.0), multilocus sequence typing (MLST v2.0), ARGs/virulence genes (Abricate v1.2.0; CARD v3.2.7, VFDB v202310), and a cgSNP-based phylogenetic tree were constructed using Snippy v4.6.0 with the Salmonella Typhimurium reference genome (GCA_020714865.1). Twelve serotypes were identified; with Salmonella Typhimurium (65.0%, 39/60) as the dominant serotype, widely distributed across clinical, food, and outbreak sources, followed by Salmonella Enteritidis (13.3%, 8/60). Salmonella Typhimurium had prevalent ST34 (59.0%) and ST19 (38.5%); ST34 was confirmed as a locally dominant clone compared to the globally common ST19. All Salmonella Enteritidis were ST11. Five ARG categories (60 types) were detected: aminoglycoside resistance genes (96.7%) were most common, followed by β-lactam (65.0%) and sulfonamide (63.3%) resistance genes. Notably, Salmonella Typhimurium exhibited a high multidrug resistance (MDR) rate of 64.1%, which was significantly higher than that of Salmonella Enteritidis (12.5%). Core virulence genes (e.g., SPI-1, TTSS-1) were ≥95% conserved; serotype-specific genes (e.g., cdtB) were strain-specific. The 60 strains were divided into 14 clusters, with 76.7% (46 strains) assigned to 3 major clusters, confirming epidemiological links between outbreaks and sources. Salmonella Typhimurium ST34/ST19 with a high MDR rate is the dominant epidemic clone in the Meishan region, posing significant public health risks. cgSNPs are useful for source tracing. Targeted surveillance of dominant clones and stricter antibiotic regulation are imperative.

Eucalyptus citriodora (lemon eucalyptus) is a medicinal plant commonly used as an antiseptic agent to prevent infection and promote healing. The aim of this exploration was to investigate for the first time the antibacterial mode of action of a gas chromatography-mass spectrometry chemically characterized E. citriodora essential oil (EO) obtained by microwave-assisted hydrodistillation. First, the chemical investigation revealed citronellal (30.67%) and citronellol (19.14%) as the major components. E. citriodora EO represented remarkable antibacterial properties, as demonstrated by significant zone of inhibition in the disc-diffusion test against all tested bacterial pathogens, including Listeria innocua ATCC 33090, L. monocytogenes ATCC 13932, Proteus mirabilis ATCC 25933, Salmonella typhimurium ATCC 700408, and Pseudomonas aeruginosa ATCC 27853. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values confirmed these findings showing antibacterial efficacy at low concentrations ranging 5.75-92 µg/mL for MICs and 11.5-184 µg/mL for MBCs. These results were comparable with gentamicin. The MIC_index revealed that E. citriodora EO has bactericidal effects. We evaluated the antibacterial properties of E. citriodora EO and determined its mode of action using advanced tests with P. aeruginosa as a typical pathogen. The time-kill test revealed dose-dependent inhibitory effects on the cell proliferation of P. aeruginosa, affecting its membrane permeability based on the time and concentration of the EO. E. citriodora EO also caused damage to the cell membrane, resulting in leakage of cellular constituents, including RNA and DNA. Anti-quorum sensing activity was tested by inhibiting biofilm formation, showing that E. citriodora EO effectively inhibited biofilm formation. The UV-visible investigation on the release of cellular materials absorbed at 260 nm showed significant leakage of cytoplasmic substances, including proteins, DNA, and RNA, indicating devastation to bacterial cell membrane integrity. In addition, the use of E. citriodora EO significantly inhibited P. aeruginosa adhesion on 304 L stainless-steel surface, making it more suitable for applications requiring better wetting ability and surface interactions, particularly in food production. [Figure: see text].

Antimicrobial resistance in Salmonella infections has become a growing global public health threat. This study was conducted to characterize the antibiotic resistance profiles and molecular typing characteristics of Salmonella isolates from diarrhea patients in Wanzhou district, Chongqing Municipality. A total of 66 Salmonella strains were isolated 769 from clinical samples of patients with diarrhea. Of the 11 serotypes identified, the top three were Salmonella 1,4,[5],12:i:- (n = 23), Salmonella Typhimurium (n = 17), and Salmonella Thompson (n = 8). Thirteen distinct sequence types (STs) were identified among the 66 Salmonella isolates, with ST34 (30.3%, 20/66) and ST19 (25.8%, 17/66) emerging as the predominant epidemic clones. Forty-two different antimicrobial resistance genes were identified. The aminoglycoside resistance genes aac(6')-Iaa (n = 68, 98.48%), β-lactam resistance genes blaTEM-1B (n = 41, 62.12%), and tetracycline resistance genes tet(A) (n = 32, 48.48%) were the most predominant. The co-existence of blaCTX-M/blaCMY-2 and qnrS was found in 11 strains. Salmonella from diarrhea patients in Wanzhou district showed high resistance (54.55-77.27%) to ampicillin, tetracycline, and streptomycin. Over half (59.10%) of the isolates exhibited multidrug resistance (MDR). A total of 4 isolates (2 S. Typhimurium and 2 S. Thompson) showed resistance to both fluoroquinolones and third-generation cephalosporins. Two isolates each of S. Typhimurium and S. Thompson displayed resistance to both fluoroquinolones and third-generation cephalosporins. Point mutations leading to amino acid changes were identified in gyrA and parC genes. Core genome single-nucleotide polymorphism showed phylogenetic clustering of the isolates with the same Multilocus sequence typing or serotype. Using a threshold of 15 core-genome SNPs, we speculated that six related epidemiological events existed. These findings underscore the necessity for ongoing surveillance of MDR patterns and molecular characteristics of Salmonella, together with prudent antibiotic use, to curb further dissemination and support the development of effective prevention and control strategies.

An investigation into an outbreak of Salmonella enterica serovar Enteritidis (S. Enteritidis) infections in Canada was initiated in October 2021 after a cluster of cases was identified through whole-genome sequencing. A total of 118 cases were identified in five provinces, related by 0-4 whole-genome multilocus sequence typing allele differences. Cases became ill between September 6, 2021 (symptom onset date) and January 27, 2022 (specimen isolation date). The median age of cases was 30 years (range: 1-89 years), and 64% were female. Five hospitalizations and two deaths were reported. Early in the investigation, a cluster of illnesses was identified that ate at different locations of the same restaurant chain (Restaurant Chain A). Several hypothesis-generating methods were conducted to identify the source, including: case re-interviews, menu review, ingredient analysis, traceback investigations, and sampling of food items. These methods identified multiple fresh produce items as possible hypotheses, but the source of the outbreak was identified when a sample of Brand X Individually Quick Frozen (IQF) Corn from Restaurant Chain A tested positive for the outbreak strain of S. Enteritidis. In total, 87% (75/86) of cases reported exposure to, or potential exposure to, corn. Based on the distribution records, 91% (68/75) of these cases could be linked to the recalled Brand X IQF Corn, and of those, 88% (60/68) consumed food from Restaurant Chain A. This article summarizes the first known outbreak investigation of Salmonella associated with frozen corn in Canada and adds evidence to the potential food safety risks associated with frozen vegetables.

Probiotics are critical for resisting the colonization of foodborne pathogens in gut. Lactiplantibacillus plantarum ZDY2013 has been proven to have multiple biological activities, including antagonizing pathogens. In this study, we systematically evaluated the protective effects of live and heat-killed L. plantarum ZDY2013 on Salmonella enterica serotype Typhimurium infection and investigated the potential mechanisms using mice infection model, HT-29 epithelial cell model, and RAW264.7 macrophage model. The results showed that live and heat-killed L. plantarum ZDY2013 could effectively reduce the Salmonella load in mice, improve the intestinal barrier by upregulating the expression of tight junction proteins (Zonula occludens protein 1 and Claudin-1) and the number of goblet cells, and alleviate the inflammation by decreasing the level of proinflammatory cytokines (interleukin-1β, tumor necrosis factor-α, interferon gamma and IL-6). In addition, L. plantarum ZDY2013 could significantly reduce the adhesion and invasion of S. Typhimurium to HT-29 epithelial cells, activate macrophages and enhance its bactericidal ability. These results indicated that live and heat-killed L. plantarum ZDY2013 has the potential to be developed as a functional health food against S. Typhimurium infection.