Deshun Xu

The monophasic Salmonella Typhimurium variant (1,4,[5],12:i:-) is a growing global public health and food safety concern. This study analyzed 60 such isolates collected in Huzhou (2023–2025), including 16 outbreak strains. All isolates belonged to ST34 and carried 211 virulence genes. Antimicrobial susceptibility testing showed universal resistance to tetracycline (100%) and a high multidrug resistance rate (96.67% resistant to ≥ 3 antibiotic classes). Whole-genome sequencing identified 39 resistance genes; aac(6´)-Iaa was present in all strains, and 48.33% carried ≥ 4 resistance genes. Phylogenetic analysis revealed high overall homology with localized evolutionary traits. Notably, clinical outbreak and food-derived isolates were clonally identical (0 SNP difference).

Objective: Salmonella serovar Typhimurium (S. Typhimurium) and its monophasic variant, Salmonella 4,[5],12:i:-, have become two of the most frequently isolated serovars worldwide, in both humans and animals. This study investigated the antimicrobial resistance and genomic characteristics of these two serovar Salmonella. Methods: Between 2021 and 2023, a total of 90 S. Typhimurium and Salmonella 4,[5],12:i:-were collected from clinical and food samples in Huzhou. Their antimicrobial resistance phenotype and genes, virulence genes, and phylogenetic relationship were analyzed. Results: Salmonella 4,[5],12:i:-, which all belong to ST34, has become the main serotype of Salmonella isolated in Huzhou instead of S. Typhimurium. Notably, we observed a higher incidence of infections among the young population (< 5 years old). The 90 Salmonella isolates were mainly resistant to tetracycline (94.4%), ampicillin (72.2%), and trimethoprim/sulfamethoxazole (70.0%), with multidrug resistance (MDR) rates as high as 93.3%. Genome sequencing indicated that these isolates possessed 39 antimicrobial resistance genes and 184 virulence genes. Conclusion: This research enhances our understanding of S. Typhimurium and Salmonella 4,[5],12:i:- infections, which is helpful to guide clinical responses.

Salmonella enteritidis is a main pathogen responsible for sporadic outbreaks of gastroenteritis, and therefore is an important public health problem. This study investigated the drug resistance and genomic characteristics of S. enteritidis isolated from clinical and food sources in Huzhou, Zhejiang Province, China, from February 1, 2021, to December 30, 2023. In total, 43 S. enteritidis strains isolated during the study period were subjected to virulence gene, drug resistance gene, genetic correlation, antibiotic resistance, and multilocus sequence typing analyses. All 43 isolates were identified as ST11, and contained 108 virulence-related genes. Drug sensitivity analysis of the 43 isolates showed resistance rates of 100% to nalidixic acid and 90.70% to ampicillin and ampicillin/sulbactam. Multidrug resistance is a serious issue, with 81.40% of strains resistant to three or more antibacterial drugs. Genome sequencing indicated that S. enteritidis possessed 23 drug resistance genes, of which 14 were common to all 43 isolates. Phylogenetic analysis based on core genome single-nucleotide polymorphisms divided the 43 S. enteritidis strains into three clusters, with the 10 samples from an outbreak forming an independent branch located in cluster 3.

Campylobacter is a major foodborne pathogen that causes outbreaks and sporadic gastrointestinal disease, creating a serious disease burden. Campylobacter strains isolated from diarrhea cases (n = 11) and raw poultry meat products (n = 2) in Huzhou, including 11 Campylobacter jejuni and 2 Campylobacter coli strains, were subjected to virulence gene, drug resistance gene, genetic correlation, antibiotic resistance, and multilocus sequence typing (MLST) analyses. The 13 Campylobacter isolates were divided into 12 sequence types (STs), one of which was a new ST. The isolated strains contain multiple virulence-related genes. Drug sensitivity analysis showed that the resistance rate of the 13 isolates to nalidixic acid, ciprofloxacin, and tetracycline was 92.3%. Genome sequencing indicated that all 11 strains of C. jejuni carried the tet(O) and blaOXA resistance genes, and 2 strains of C. coli carried multiple drug resistance genes. Phylogenetic analysis based on core-genome single-nucleotide polymorphisms indicated that the 11 C. jejuni isolates from diarrhea patients and food sources are not closely phylogenetically related.

Background: Human metapneumovirus (hMPV) is one of the important pathogens in infant respiratory tract infection. However, the molecular epidemiology of hMPV among children < 14 years of age hospitalized with severe acute respiratory infection (SARI) is unclear. We investigated the hMPV infection status and genotypes of children hospitalized with SARI from January 2016 to December 2020 in Huzhou, China. Methods: A nasopharyngeal flocked swab, nasal wash, or nasopharyngeal swab/or opharyngeal swab combination sample was collected from children with SARI in Huzhou from January 2016 to December 2020. Quantitative reverse transcription-polymerase chain reaction was performed to detect hMPV RNA. The hMPV F gene was amplified and sequenced, followed by analysis using MEGA software (ver. 7.0). Epidemiological data were analyzed using Microsoft Excel 2010 and SPSS (ver. 22.0) software. Results: A total of 1133 children with SARI were recruited from 2016 to 2020. Among them, 56 (4.94%) were positive for hMPV-RNA. Children < 5 years of age accounted for 85.71% of the positive cases. The hMPV incidence was high in spring and winter, especially in December and January to March. Phylogenetic analysis of the F-gene sequences of 28 hMPV strains showed that the A1, B1, and B2 genotypes were prevalent in Huzhou, and the dominant hMPV genotype varied according to surveillance year. Conclusions: HMPV is an important respiratory pathogen in children in Huzhou, with a high incidence in winter and spring in children < 5 years of age. In this study, genotypes A1, B1, and B2 were the most prevalent.

Background: Human metapneumovirus (hMPV) is one of the important pathogens of infant respiratory tract infection. However, the molecular epidemiological information relating to hMPV among children hospitalized patients with severe acute respiratory infection (SARI) have not been thoroughly studied as yet. To investigate the infection status and genotypes of hMPV among children hospitalized patients with SARI from January 2016 to December 2020 in Huzhou, China. Methods: A nasopharyngeal flocked swab, nasal wash or combination of nasopharyngeal swab and oropharyngeal swab samples were collected from children with SARI in Huzhou from January 2016 to December 2020. RT-PCR was used to detect the nucleic acid of hMPV. F gene was amplified and sequenced for the positive nucleic acid samples of hMPV. The obtained gene sequences were analyzed by MEGA software (version 7.0). Epidemiological data were analyzed using Microsoft Excel 2010 and service solutions (SPSS) 21.0 software.Results: A total of 1133 children with SARI were collected from 2016 to 2020. Among them, 56 cases were positive for hMPV nucleic acid, with a positive rate of 4.94%. Children under 5 years old accounted for 85.71% of the total positive cases. Higher activity of hMPV infection could be seen in the period in Spring and Winter. and the main epidemic months were December and January-March. The F gene sequences of 28 strains of hMPV were obtained by co-sequencing. Phylogenetic analysis showed that there were A1, B1 and B2 genotypes of hMPV prevalent in Huzhou, and the dominant genotype of hMPV during our study period varied according to surveillance year.Conclusions: HMPV is one of the important pathogens causing acute respiratory virus infection in children in Huzhou, with high incidence in winter and spring seasons and children under the age of 5，A1, B1 and B2 are three prevalent genotypes.

Background: Human metapneumovirus (hMPV) is one of the important pathogens of infant respiratory tract infection. However, the molecular epidemiological information relating to hMPV among children hospitalized patients with severe acute respiratory infection (SARI) have not been thoroughly studied as yet. To investigate the infection status and genotypes of hMPV among children hospitalized patients with SARI from January 2016 to December 2020 in Huzhou, China. Methods: A nasopharyngeal flocked swab, nasal wash or combination of nasopharyngeal swab and oropharyngeal swab samples were collected from children with SARI in Huzhou from January 2016 to December 2020. RT-PCR was used to detect the nucleic acid of hMPV. F gene was amplified and sequenced for the positive nucleic acid samples of hMPV. The obtained gene sequences were analyzed by MEGA software (version 7.0). Epidemiological data were analyzed using Microsoft Excel 2010 and service solutions (SPSS) 21.0 software.Results: A total of 1133 children with SARI were collected from 2016 to 2020. Among them, 56 cases were positive for hMPV nucleic acid, with a positive rate of 4.94%. Children under 5 years old accounted for 85.71% of the total positive cases. Higher activity of hMPV infection could be seen in the period in Spring and Winter. and the main epidemic months were December and January-March. The F gene sequences of 28 strains of hMPV were obtained by co-sequencing. Phylogenetic analysis showed that there were A1, B1 and B2 genotypes of hMPV prevalent in Huzhou, and the dominant genotype of hMPV during our study period varied according to surveillance year.Conclusions: HMPV is one of the important pathogens causing acute respiratory virus infection in children in Huzhou, with high incidence in winter and spring seasons and children under the age of 5，A1, B1 and B2 are three prevalent genotypes.

Vibrio parahaemolyticus is responsible for seafood-borne gastroenteritis worldwide. Isolates of V. parahaemolyticus from clinical samples (n = 54) and environmental samples (n = 38) in Huzhou were analyzed by serological typing, virulence gene detection, antibiotic resistance testing, and pulsed-field gel electrophoresis (PFGE) for molecular typing. O3:K6 was the main serotype and tlh+tdh+trh- was the most frequently detected virulence genotype in clinical strains. O2:Kut was the main serotype and tlh+tdh-trh- was the most frequently detected virulence genotype in environmental strains. Antibiotic resistance testing indicated that the isolates were highly resistant to ampicillin (90.76%), followed by gentamicin and tetracycline. Following the restriction enzyme NotI digestion, the 91 strains yielded 81 PFGE patterns, and 16 clones had similarity values of > 85.00%, indicating a high level of diversity. Finally, there may be cross-contamination between freshwater and seawater products, so it is necessary to strengthen supervision of food processing.

Meat adulteration has recently become an issue of increasing public concern. In addition to posing a health risk to consumers with metabolic disorders or allergies, meat adulteration has triggered many economic and religious problems. Chicken meat is one of the eligible candidates for meat adulteration due to its low cost and ready availability.This study developed a loop-mediated isothermal amplification (LAMP) assay coupled with a lateral flow dipstick (LFD) to identify chicken in non-chicken products. , we optimized the amplification time and temperature to obtain the best result . This method is performed at a constant temperature in a water bath and complete in 1 hour. No precision instruments or equipment are needed. With a one-step reaction and easy operation, the testing cost is low. Whith high sensitive and specific, this method provide a valuable method for identifying chicken in non-chicken products. which meets the requirements of on-site inspection and detection.