Foodborne pathogens and disease最新文献

The global rise in fluoroquinolone (FQ) resistance among Salmonella spp. has prompted the WHO to classify these strains as high-priority pathogens. However, the trade-offs between FQ resistance and bacterial fitness or virulence, along with the underlying mechanisms, remain insufficiently investigated. In this study, FQ-resistant Salmonella enterica strains were generated via artificial in vitro induction using ciprofloxacin (0.125-8 mg/L). We comprehensively characterized the resultant strains regarding multidrug resistance, biological fitness, pathogenicity, and genetic profiles. Results showed that induction via laboratory serial passage conferred multidrug resistance but imposed significant fitness costs, including flagella reduction, impaired motility, increased auto-aggregation, and enhanced biofilm formation. Notably, the resistant strains exhibited compromised adhesion and invasiveness, and animal models confirmed attenuated pathogenicity compared to the wild-type strain. Mechanistically, qPCR revealed significant downregulation of key virulence genes (e.g., spvB, ssaV, sipB, and pipB), while resequencing identified specific mutations and indels in virulence and drug resistance loci. These findings elucidate the phenotypic and genetic shifts associated with FQ-induced resistance, offering critical insights for predicting infection outcomes and refining antimicrobial strategies.

Multidrug resistance in foodborne pathogens poses a critical threat to food safety and public health. Enterobacter hormaechei is an emerging pathogen with wide environmental prevalence and is capable of causing severe infections. Bacteriophage-based intervention has gained significant recognition as a sustainable approach to combat foodborne pathogens and address antimicrobial resistance in food production systems. Despite this, research on E. hormaechei-specific phages is facing substantial challenges, primarily due to insufficient phage collections and inadequate genomic characterization of existing isolates. In this work, two novel virulent phages (Ehp-YZU-L3 and Ehp-YZU-L4) were isolated from wastewater samples in Yangzhou. Their morphological, biological, and genomic features were characterized. The two phages belonged to the Myoviridae family, with a latency period (10 and 40 min) and high burst size (192 and 292 plaque-forming unit [PFU]/host cell), and an optimal multiplicity of infection of 0.01. The complete genomic sequences of phages ranged from 163,779 to 170,652 bp and GC content of 39.8 - 40.2%, which consisted of 296 and 275 open reading frames of phage Ehp-YZU-L3 and Ehp-YZU-L4. The absence of both virulence-related genetic elements, antimicrobial resistance, and lysogeny-related genes in two genomes was confirmed. Two phages exhibited strong inhibitory effects against E. hormaechei in pork by a phage-dosage-dependent way, with a reduction range of bacterial counts by 1.73-2.87 Log CFU/g for Ehp-YZU-L3 and 1.96-3.20 log CFU/g for Ehp-YZU-L4 at 37°C for 4 h. These findings demonstrate considerable potential of these two phages for the biocontrol of E. hormaechei contamination in food production systems.

Non-aureus staphylococci (NAS) and mammalicocci (collectively NASM) are coagulase-negative staphylococci, though they are less well-known than Staphylococcus aureus. Certain species within the NASM group have been associated with foodborne illnesses due to their ability to produce enterotoxins that are similar to those produced by S. aureus. In this study, 180 samples of ready-to-eat foods were examined, including 30 samples each of soybean cheese, cow milk cheese, yogurt, and meat pie, along with 60 samples of mixed vegetables. Isolation of the bacteria was performed using selective culture media technique, followed by biochemical testing, including a coagulase test. The taxonomic characterization of NASM was carried out using 16S rRNA gene sequencing, and antibiotic susceptibility was done using the Kirby-Bauer disk diffusion method. Of the total samples examined, 133 exhibited bacterial growth on Mannitol Salt Agar. This included samples of soybean 27 (15%), cow milk cheese 30 (16.67%), mixed vegetables 39 (21.67%), yogurt 27 (15%), and meat pie 10 (5.56%). Among these isolates, 20 (15.037%) displayed nonpigmented characteristic growth on nutrient agar and were subsequently subjected to biochemical testing. Specifically,9 (45%) of the isolates were identified as M. sciuri, 2 (10%) as S. edaphicus, 3 (15%) as S. arlettae, 1 (5%) as S. hominis, 2 (10%) as S. gallinarum, and 3 (15%) as S. ureilyticus. Approximately 90% of the isolates showed resistance to three or more antibiotics, with isolates 11, 16, and 21 showing resistance to five or more antibiotics. The result indicated M. scuiri as a frequent contributor to ready-to-eat food contamination, and three of the strains showed multidrug resistance. Although the risk of foodborne illness may be relatively low in NASM, the potential for the spread of antibiotic resistance genes to more pathogenic species of the family Staphylococcaceae such as S. aureus remains a significant concern.

Giardia, a flagellated protozoan, is widely distributed in wild rodents. To characterize the presence of Giardia in wild rodents in southern China, this study collected 344 fecal samples from wild rodents in Guangxi, Hunan, and Yunnan provinces. The β-giardin gene (bg) was amplified to identify the presence of Giardia sp. The results showed that 48 samples (13.95%, 48/344) tested positive for Giardia, including three positives for G. duodenalis (assemblage G n = 1, assemblage F n = 2) and 45 positives for G. microti. Among these, Microtus fortis had the highest prevalence at 30.22% (42/139), followed by Apodemus agrarius (7.14%, 3/42). Rattus flavipectus showed a prevalence of 2.56% (1/39), while Bandicota indica had a rate of 5.13% (2/39). The prevalence of Giardia in males (18.27%, 36/197) was slightly higher than in females (8.16%, 12/147). To the best of our knowledge, the present study reported the detection of assemblage F and assemblage G in B. indica for the first time. In addition, G. microti was found exclusively in M. fortis and a few A. agrarius. This study enriches the epidemiological data on Giardia in wild rodents and provides new insights for future research.

Staphylococcus aureus is a foodborne zoonotic pathogen that threatens food safety and public health. However, few people have conducted long-term and systematic studies on S. aureus contamination in food in Yantai City. To investigate the contamination situation of S. aureus in food and improve the ability of early warning and control of foodborne diseases, a total of 2384 samples from 17 categories were collected from 13 monitoring points in Yantai City, from 2010 to 2023. Forty-four samples were positively detected for S. aureus, with a detection rate of 1.85% (44/2384). The detection rate of S. aureus was highest in Zhifu District (4.12%), followed by Penglai District (2.45%), Zhaoyuan District (2.37%), Kaifa District (2.19%), and Longkou District (1.98%). Positive detection rates were higher in frozen rice and flour products at 8.82% (6/68), quick-frozen dishes at 5.56% (1/18), aquatic products at 4.05% (3/74), and meat and meat products at 3.55% (27/760). Positive detection rates in samples from the first, second, third, and fourth quarters were 0% (0/44), 2.21% (20/906), 2.13% (22/1033), and 0.50% (2/401), respectively. Positive detection rates in bulk and prepackaged samples were 2.33% (36/1546) and 0.95% (8/838), respectively, with statistically significant differences (χ² = 5.66, p < 0.05). Positive detection rates were significantly different for samples collected from different sampling stages, of which at production and processing stages was 7.78% (20/257), catering stages 1.38% (10/727), and distribution stages 1% (14/1400) (χ² = 56.41, p < 0.05). Frozen rice and flour products, quick-frozen dishes, aquatic products, and meat and meat products are the main food products contaminated with S. aureus, and the resulting secondary contamination is a hidden danger for the occurrence of foodborne diseases, which should be given sufficient attention.

This systematic review and meta-analysis aimed to evaluate the global epidemiology, subtype (ST) distribution, and zoonotic potential of Blastocystis sp. in birds. A systematic review of the literature up to July 26, 2024, identified 47 articles/98 datasets meeting the inclusion criteria, covering data from 19 countries and over 41 bird species. Total estimates and 95% confidence intervals (CIs) were calculated using a random-effects model. The weighted prevalence of Blastocystis sp. in birds was 26.4% (95% CI: 22.5-30.6%), varying by location and species. The highest pooled prevalence was in guinea fowls at 83.3% (95% CI: 36.9-97.7%), followed by pheasants at 50.4%, flightless birds at 47.8%, peafowls at 41%, exotic birds at 34.4%, chickens at 24.9%, uncategorized birds at 24.4%, Anatidae birds at 24.3%, red-crowned cranes at 19.7%, quails at 15.8%, and pigeons at 12.8%. Subgroup analysis of Blastocystis sp. prevalence was performed based on publication years, countries, continents, WHO regions, and sample sizes. Birds can be the proper source of infection for 20 Blastocystis sp. STs (ST1-ST10, ST13, ST14, ST20, ST21, ST23-ST25, and ST27-ST29), with 12 STs (ST1-ST10, ST14, and ST23) capable of infecting humans. The findings revealed that birds should not be ignored in terms of the possible transmission of Blastocystis sp. zoonotic infections to humans. Moreover, parasitic infections, such as Blastocystis sp., can affect the health of poultry, causing gastrointestinal issues that impact growth and productivity, which requires special attention in this field.

Salmonella Infantis has recently been one of the most prevalent serotypes in poultry and has been identified in human salmonellosis cases worldwide. Multidrug-resistant (MDR) Salmonella Infantis has emerged as a significant threat to both poultry production and public health due to its increasing prevalence and global dissemination. We identified the occurrence of an MDR Salmonella Infantis clone in broiler flocks in Korea, and the clone was characterized to explore potential genetic causes for its high prevalence and rapid spread in broiler production. In total, 220 Salmonella strains isolated between 2020 and 2023 from broiler flocks were serotyped, and 50 strains were identified as Salmonella Infantis (22.7%). The isolates were tested for antimicrobial susceptibility, and their genetic characteristics were analyzed using pulsed-field gel electrophoresis (PFGE), multilocus sequence typing, and whole genome sequencing (WGS). Forty-six strains of Salmonella Infantis isolated since 2020 were resistant to at least five antimicrobial families including ampicillin, cephalosporins, chloramphenicol, nalidixic acid, and tetracycline. The strains showed 10 PFGE patterns and a single multilocus sequence type 32. Eight representative MDR strains were analyzed by WGS. Seven of the eight strains carried the plasmid of emerging Salmonella Infantis-like megaplasmids recognized globally in emergent MDR Salmonella Infantis. They had a high prevalence of seven antimicrobial resistance genes, six of which were identified in plasmids. Also, they all share virulence genes, including fimbrial adherence determinants and secretion system components, and showed a clonal relationship to strains from North America, South America, and West Asia, suggesting potential international dissemination routes. To mitigate the risks associated with the rapid spread of MDR Salmonella Infantis in poultry production and its potential impact on human health, this study provides valuable insights into implementing effective control measures to reduce Salmonella in broiler production in Korea. Further highlighting the critical importance of enhanced biosecurity and continuous surveillance.

Growing evidence supports the efficacy of antimicrobial peptides against foodborne pathogens, though their antimicrobial spectrum and mechanism can vary depending on their origin. We investigated the antimicrobial spectrum of antimicrobial peptides derived from Lactobacillus paracasei A1, their effects on the survival rate and bactericidal mechanisms against Vibrio parahaemolyticus, and identified the functional short peptides within them. The crude extracts of antimicrobial peptides exhibited antibacterial properties against 13 pathogenic bacteria, showing strong inhibition of V. parahaemolyticus by disrupting the structural integrity of cell membranes. At minimum inhibitory concentrations, these peptides significantly disrupted the initial adhesion, membrane formation, and existing biofilms of V. parahaemolyticus, effectively inhibiting pathogen spread, enhancing the efficacy of antimicrobial agents, and reducing food safety risks. LC-MS/MS identification revealed four effective short peptides, all demonstrating potent bacteriostatic effects against V. parahaemolyticus. Our findings indicate that antimicrobial peptides can effectively destroy bacterial structures as well as the stability and regeneration of biofilms, making them promising candidates for use as food additives to control foodborne pathogens.

Pork contaminated with bacteria can shorten the shelf life and cause foodborne diseases. Bacterial community analysis of raw pork in sale process can help identify bacteria associated with food quality and safety. In this study, 52 pork samples were collected from various supermarkets and farmers' markets in Qingdao, China. And the bacterial community structures in pork were analyzed by high-throughput sequencing of 16S rDNA. Both the α-diversity and β-diversity of bacterial communities in pork samples from farmers' market were higher than those from supermarkets (ANOSIM test, R² = 0.049, p = 0.016). Proteobacteria (88.8%) was the most dominant phylum, and Photobacterium (44.5%) and Acinetobacter (23.9%) were the top two dominant genera in all pork samples. The abundance of most dominant bacterial genera was higher in pork samples from farmers' markets than those from supermarkets, But Photobacterium (ranking first) was just the opposite (p = 0.003). The bacterial communities in pork hadn't obvious clustering characteristics between the two sale locations, while Photobacterium was considered as the biomarker in pork samples from supermarkets according to LefSe analysis (linear discriminant analysis score >4.0). A strong correlation was observed between some samples (R >0.7) collected from different stalls within the same sampling location, indicating cross-contamination possibility in sale process. The findings may have implications for the quality and safety control of pork, particularly for microbial prevention and control during selling and consumption.

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.