Foodborne Pathogens and Disease

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.

Campylobacter is one of the leading causes of bacterial foodborne diarrheal diseases throughout the world. Reported outbreaks of Campylobacter are infrequent in China. This article described such an outbreak among students from a junior high school in East China during November 2019. A total of 40 samples were collected as follows: 24 stool samples from patients, 12 stool samples from kitchen staff members, and 4 water samples from cafeteria. The stool samples were tested for the presence of Salmonella, enterotoxigenic Escherichia coli, Shigella, Vibrio parahaemolyticus, Vibrio cholera, Listeria monocytogenes, Staphylococcus aureus, Yersinia enterocolitica, Bacillus cereus, Clostridium perfringens, norovirus, rotavirus, adenovirus, astrovirus, and sapovirus by real-time polymerase chain reaction (PCR). Pulsed-field gel electrophoresis (PFGE), next-generation sequencing, and antimicrobial susceptibility testing were performed to determine the relatedness of the Campylobacter jejuni isolates in this outbreak. Forty-seven cases were reported with diarrhea among 569 seventh grade students and staff. In these 47 cases, we detected that C. jejuni through real-time PCR in 16 fecal samples was positive, whereas the remaining fecal samples were tested negative by real-time PCR. Only three C. jejuni strains were isolated from stool samples of case patients, and all of them showed 100% PFGE similarity to strain ST6913. Whole genome sequencing analysis revealed no single nucleotide variation in the three isolates. This is one of the few reports in China about outbreak caused by C. jejuni. C. jejuni ST6913 was responsible for this outbreak.

Foodborne botulism is a rare but highly lethal disease. The botulinum neurotoxin (BoNT) that causes botulism is produced by Clostridium botulinum (C. botulinum) and other clostridia. In this study, we characterized C. botulinum strains isolated during food poisoning events in Sichuan Province from 1990 to 2024 by analyzing whole-genome sequencing data. Statistical analyses of the geographical distribution food sources of strains suggested that the primary sources of contamination were associated with specific regions and food types. The isolates were further compared with reference strains using average nucleotide identity analysis to reveal their genetic diversity and evolutionary relationships. Among the eight strains, five strains belonged to Group I, and the other three strains belonged to Group II. All strains belonging to Group I (SC001, SC002, SC003, SC006, and SC009) were assigned to five totally different recognized ST types (ST-2 to ST-51). In addition, analysis of BoNTs subtypes demonstrated that the types of BoNTs causing botulism in Sichuan were mainly types A, B, and E. Among them, some rare subtypes of BoNT reported for the first time in China, such as BoNT/B4, BoNT/E12, and BoNT/A5(B3), and no specific subtypes were predominant in the botulism incidents. This study is critical for disease surveillance and early warning systems, while also providing a basis for food safety regulation, clinical diagnosis, and treatment in the future.

Klebsiella quasipneumoniae is a recently described species that can be differentiated from Klebsiella pneumoniae. However, in clinical settings, they are frequently misidentified as K. pneumoniae. In this study, our objective was to conduct genomic characterization and bioinformatics analysis of K. quasipneumoniae subsp. quasipneumoniae (KpII-A) isolated from a sample obtained from a retail fish market in Assam, India. Notably, this particular isolate was identified as K. pneumoniae when identified using BD Pheonix™ M50 (BD Difco, USA). This represents a serious pitfall of conventional microbiological methods for distinguishing between K. pneumoniae and K. quasipneumoniae. In this connection, identifying differences in nuclear gene content is key to avoid misidentification. The isolate was confirmed to be KpII-A using species identification by Mash Screen and whole-genome sequencing by the Illumina platform. We report the draft genome sequence of this strain, comprising of 53 contigs with an average GC content of 58.11%. The annotation revealed 5,095 protein coding sequences, 69 tRNA genes, and 4 rRNA genes. The isolated strain acknowledges the presence of oqxA, oqxB, fosA, and bla_OKP-A-3 antimicrobial resistance genes (ARGs). Additionally two phage genomes were detected in contigs 3 and 19 of the bacterial genome. Based on the multilocus sequence typing and genome sequencing, the isolate was identified as a novel sequence type, ST5655, within the species K. quasipneumoniae under the phylogroup KpII-A. The presence of antimicrobial resistance genes in KpII-A, isolated from retail fish samples, raises concerns regarding transmission across barriers in ecological niches and possible transmission to consumers. Given that fish may serve as a potential vehicle for ARG transmission, our findings are highly relevant and paramount to human health. Moreover, our study supports the robustness of the sequence-based microbial identification.

Lactiplantibacillus plantarum is a member of lactic acid bacteria that improves the quality of fermented foods while also having a positive impact on human health. In this study, L. plantarum F2 was studied for characteristics such as biochemical and genetic identification, metabolite production, antimicrobial activity, and plasmid content. This strain exerts antimicrobial activity against some Gram-positive and Gram-negative pathogens (Listeria monocytogenes, Staphylococcus aureus, Salmonella, and Escherichia coli) with inhibition zone diameters ranging between 17.0 and 29.0 mm; it can ferment glucose, arabinose, galactose, lactose, and demonstrated the ability to grow at high temperature (50°C). Another physiological specification of the strain was the morphology of the isolate in selective medium, the de Man, Rogosa, Sharpe medium (MRS medium containing triphenyl tetrazolium chloride), which exhibits a chromogenic colony (characterized as purple colonies) on the modified-MRS (mMRS) medium. Metabolites such as lactic acid and diacetyl production of the strain F2 were also investigated using chromatography and found to be 10.07 and 0.05 µg/mL, respectively. The peptides of the isolate’s cell-free supernatant were determined to be ∼80 kDa, and finally, the plasmid isolated from the strain F2 was identified as L. plantarum strain KLDS1.0386 plasmid p4, which may be responsible for some characteristic properties, such as antimicrobial peptide production of the strain.

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.

During the 2019 Chinese National Microbiological Food Safety Surveillance program, Listeria monocytogenes was detected in ice cream samples produced by Manufacturer A. By comparing the sequences of isolates derived from the ice cream with those of isolates derived from humans, we identified one human-derived isolate that was genetically indistinguishable from one ice cream-derived isolates. The patient was hospitalized with listeriosis in Beijing, China in March 2019. Food history obtained from the patient indicated that he had consumed ice cream produced by Manufacturer A during the 30-day period before the onset of illness. No cases of listeriosis were detected after the ice cream produced by Manufacturer A was removed from the shelves. Overall, this report presents the first case of L. monocytogenes infection associated with ice cream in China.