Foodborne pathogens and disease最新文献

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.

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.

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.

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.

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.

This study aimed to explore the ameliorative effect of Millettia speciosa Champ. polysaccharides (MSP) on excessive exercise-induced fatigue (EF) mice. The physicochemical characterization and in vitro antioxidant activities were analyzed. The fatigue-related biochemical indexes were determined, and gut microbiota was analyzed by 16S rDNA sequencing. The results showed that MSP primarily consists of total carbohydrates, uronic acids, and proteins. It was mainly composed of glucose, arabinose, and galactose. Additionally, MSP showed good scavenging effects on free radicals. In the experiment of EF mice, MSP intervention effectively extended the pole-climbing and swimming time, significantly increased the levels of muscle and liver glycogen, blood glucose, adenosine triphosphate, glutathione peroxidase, and superoxide dismutase, while significantly decreased the levels of fatigue-related lactate dehydrogenase, creatine kinase, and urea nitrogen. Furthermore, MSP intervention reduced harmful bacteria (Helicobacter, Anaerotruncus, Erysipelatoclostridium, and Lachnospiraceae_FCS020_group), and enriched the beneficial bacteria (Lactobacillus, Alistipes, Ruminococcaceae, and Roseburia). Therefore, MSP may utilize the gut microbiota as a target to alleviate fatigue caused by excessive exercise.

The aim was to longitudinally evaluate the association between antimicrobial exposure and resistance occurrence within generic Escherichia coli and Enterococcus spp. populations in feedlot beef cattle raised conventionally or raised without antimicrobials. Angus steers (n = 180) were sorted into 1 of 2 treatments over 2 consecutive years (108 in yr 1 and 72 in yr 2): steers raised without antimicrobials (NAT) and conventionally raised steers exposed to antimicrobials (CONV). Pens within treatment were adjacent and separated by five empty pens from the other treatment. Monensin and tylosin were included in CONV steer diets. On d 123, CONV steers received a metaphylactic antimicrobial. Longitudinal diet (n = 6/year) and fecal (n = 5/year) sampling timepoints were collected to determine E. coli and Enterococcus spp. concentration, prevalence, and resistance patterns. Dietary Enterococcus spp. concentrations, and erythromycin (8ERY^R; 128ERY^R), tetracycline (TET^R), trimethoprim-sulfamethoxazole (COT^R), and cefotaxime (CTX^R) resistant E. coli concentrations and prevalence were greater in NAT diets than CONV diets (p < 0.02). Fecal E. coli concentrations tended to be greater in NAT steers than CON steers (p = 0.07). Fecal TET^R E. coli concentrations were greater in CONV steers than NAT steers (p = 0.03). Fecal COT^R and CTX^R E. coli prevalence was greater for CONV steers at the beginning of the finishing phase while greater for NAT steers at the end of the finishing phase (p < 0.01). Fecal Enterococcus spp. concentrations did not differ between treatments (p = 0.11). Concentrations of 8ERY^R and 128ERY^R Enterococcus spp. were greater in CONV steers on d 64, 130, and 168 than NAT steers (p < 0.05). Overall, antimicrobial resistant Enterococcus spp. and E. coli were detected regardless of antimicrobial exposure.

Objective: The emergence of antibiotic-resistant Staphylococcus aureus, especially methicillin-resistant S. aureus (MRSA), poses a great challenge for animal and public health. This study aimed to isolate a broad-spectrum and high-efficiency MRSA phage and explore the phage-antibiotic synergistic effect on MRSA. Results: Phage STPX-6 belongs to Caudovirales, Podoviridae. It has a hexahedral head and a short tail. Its genome length was 17,007 bp, and it did not contain resistance genes and virulence genes. STPX-6 lysed 79.6% (133/167) of 167 S. aureus and 87.96% (95/108) of MRSA from different sources. The titer of phage was 1.18 × 10¹⁰ PFU/mL, the optimal multiplicity of infection was 1, the latent period and lysis period were about 10 min and 60 min, respectively, and the burst amount was 68 PFU/cell. At 50°C and 70-90°C, the titer of STPX-6 was maintained at about 10¹⁰ PFU/mL and at least 10³ PFU/mL, respectively. In the range of pH 4-12, the titer of phage remained above 10⁸ PFU/mL, and it remained above 10⁴ PFU/mL at pH 2, 3, 13, and 14. The combined application of phage STPX-6 and enrofloxacin, doxycycline, ampicillin could reduce the minimum inhibitory concentration (MIC) of the three antibiotics to 1/4 MIC, 1/16 MIC, and 1/2 MIC, respectively. Conclusion: This study found that for the host MRSA, lytic phage STPX-6 had the characteristics of a broad lytic spectrum, a short latent period, strong adaptability and strong tolerance to high temperature, a strong acid and strong alkali environment, and might maintain certain activity under extreme environment. More importantly, the combination of phage STPX-6 with enrofloxacin, doxycycline, and ampicillin could reduce the antibiotic concentration used for MRSA. In other words, phages as new antibacterial agents have received increasing attention. The combined application of phages and antibiotics provides a new method for controlling multidrug resistant bacteria and reduce the use of antibiotics.

In this study, sea buckthorn polysaccharides (SBP) were added as functional substances to chitosan (CS), and chitosan/sea buckthorn polysaccharide (SCS) composite films were prepared using the casting method. The effects of SBP addition on the optical properties, physical properties, mechanical properties, structure, antioxidant activity, and antibacterial activity of the SCS composite films were studied, and the prepared SCS composite films were used to preserve yellow cherry tomatoes. The results showed that SCS composite films exhibited good UV resistance, water solubility, and antioxidant activity, but its apparent structure, hydrophobicity, and mechanical properties needed further improvement. Meanwhile, SBP has inhibitory effects on all 8 experimental strains. In addition, the SCS composite film with the addition of 200 mg/L SBP could reduce the weight loss rate of yellow cherry tomatoes, maintain hardness, delay the decrease of total soluble solids, titratable acid, and Vitamin C content, and inhibit the accumulation of malondialdehyde. SCS composite films are beneficial for enhancing the quality of yellow cherry tomatoes during storage, and their application in fruit and vegetable preservation has development prospects.