Foodborne Pathogens and Disease

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.

Antibiotic resistance remains a global public health concern, and the prevalence of Enterobacteriaceae species that harbor antibiotic resistance genes (ARGs) is on the rise. The aim of this study was to assess the distribution of extended-spectrum beta-lactamase (ESBL)/AmpC-producing Enterobacteriaceae in vegetables cultivated on irrigated farms in Lagos, Nigeria. A total of 257 samples, including vegetable samples, irrigation water, and soil, were collected from five farms within the city. Standard microbiological and molecular biology methods were used for the isolation and characterization of bacterial genera within Enterobacteriaceae and the detection of ARGs. Antibiotic susceptibility testing was conducted using the Kirby-Bauer disc diffusion method, and ESBL production was determined by the double-disk synergy test. Fifty-eight bacterial strains were isolated from the samples, of which 52 (90%) belonged to the family Enterobacteriaceae. Ten genera from this family were represented among obtained isolates, with Klebsiella species and Escherichia fergusonii being most prevalent. In total, 85% and 52% of these isolates were resistant to amoxicillin–clavulanic acid and ceftazidime, respectively. Sixty-five percent of these isolates were multidrug-resistant (MDR), with 56% and 46% testing positive for ESBL and AmpC production, respectively. Some of the MDR isolates had Multiple Antibiotic Resistance Index (MARI) ranging from 0.4 to 0.8. bla_SHV was the dominant ESBL encoding gene detected, while bla _AmpC was detected in only 4% of isolates. Plasmids ranging in size from 2.6 to 20.35 kb were detected in some of the MDR Enterobacteriaceae isolates. The presence of MDR Enterobacteriaceae in the food chain is of public health significance, highlighting the need for continuous surveillance.

Cronobacter sakazakii, an opportunistic foodborne pathogen associated with powdered infant formula, causes severe neonatal infections, yet its interaction with gastric epithelial cells remains poorly characterized. Here, we conducted a preliminary in vitro study to evaluate early host–pathogen responses of C. sakazakii in AGS gastric epithelial cells. AGS cells were exposed to C. sakazakii ATCC 29544 at a multiplicity of infection of 100 for 2 h, and cytotoxicity and transcriptional responses were assessed by viability assay, gentamicin protection assay, and reverse transcription-quantitative polymerase chain reaction. Infection significantly reduced AGS cell viability and increased expression of bacterial virulence-associated genes (ompA and hfq) and host inflammatory genes (IL-8 and NF-ƙB) compared with mock-infected controls (p < 0.001). Gentamicin-protected recovery was consistent with bacterial entry into AGS cells, although confirmatory imaging-based analyses were not performed. These findings indicate that C. sakazakii (ATCC 29544) can elicit early cytotoxic and pro-inflammatory responses in AGS gastric epithelial cells under in vitro conditions, supporting the need for confirmatory studies in more physiologically relevant gastric study models.

Campylobacter is a foodborne pathogen that poses a serious threat to food safety and public health. Due to the limited data on the prevalence and antimicrobial resistance of Campylobacter across different retail meat sales modes in Southern China, this study primarily focuses on three sales modes of fresh, refrigerated, and frozen meat in Southern China. A total of 500 samples were collected from five cities in Guangdong Province between March and December 2021, with an overall Campylobacter detection rate of 20.8%, including only Campylobacter jejuni (53.8%) and Campylobacter coli (46.2%). The prevalence in fresh meat was significantly higher than in refrigerated and frozen meat and higher in butcher stalls than in supermarkets, with both chicken and pork showing a high prevalence. High resistance rates were also observed for ampicillin (95.2%), sulfamethoxazole (94.2%), and erythromycin (ERY; 90.4%), with 99.0% of isolates being multidrug resistant. The resistance of refrigerated and frozen meat was higher than that of fresh meat. This could be due to cold stress favoring the survival of resistant strains under selective pressure. The ERY resistance mechanisms were mainly mediated by the erm(B) gene, 23S rRNA mutations, and L22 ribosomal proteins. Multilocus sequence typing analysis indicated ST-828 clonal complex (CC828) as the most prevalent among ERY-resistant strains. This study reveals the prevalence patterns and high drug resistance levels of Campylobacter in retail meat in Southern China, providing a scientific basis for formulating targeted prevention and control measures for different sales modes.

The rising concern of multidrug-resistant pathogens and the unavailability of new antibiotics in the discovery pipeline has generated the need for alternative approaches for their control. Essential oils (EOs) and essential oil’s active components (EoCs) have been reported for their antimicrobial effect since long. In this study, we evaluated 11 EOs and 4 EoCs for their antimicrobial and antibiofilm activity. Among EOs, oregano (zone of inhibition [ZOI] = 24.62 ± 8.10 mm), cinnamon (ZOI = 18.38 ± 5.88 mm), cassia (ZOI = 20.23 ± 4.61 mm), and thyme (ZOI = 13.77 ± 5.67 mm), and among EoCs, cinnamaldehyde (ZOI = 24.69 ± 5.83 mm), carvacrol (ZOI = 24.38 ± 7.76 mm), and thymol (ZOI = 22.92 ± 7.43 mm) demonstrated the higher antimicrobial activity against the targeted pathogens. Only cinnamon (ZOI = 16.62 ± 2.58 mm) and cassia (ZOI = 15.24 ± 1.90 mm) were found to be effective as antimicrobial against Pseudomonas aeruginosa strains. Cinnamaldehyde (ZOI = 9.02 ± 2.68 mm) demonstrated weak antimicrobial activity. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and antibiofilm assays were performed in triplicate. Statistical analysis using the Kruskal–Wallis test revealed a significant overall difference between treatments (p < 0.05) against both P. aeruginosa and Staphylococcus aureus. Specifically, Dunn’s multiple comparisons test showed significant differences (p < 0.05) in MIC values between cinnamaldehyde and eugenol for P. aeruginosa with no significant difference in their MBC. For S. aureus, significant variations (p < 0.05) in MIC and MBC were observed between carvacrol and thymol, and between thyme and other oils like tea tree, cumin, and lemongrass. Antibiofilm effect of EOs and EoCs against P. aeruginosa and S. aureus was found at concentration of 0.031% for cinnamon EO and cinnamaldehyde and at 0.015 − 0.007% for carvacrol. Gas chromatography–mass spectrometry analysis of EOs and EoCs was performed to determine their bioactive compounds. The study highlights that EOs and EoCs can be used as alternative antimicrobials against food spoilage bacteria and drug-resistant pathogens.

Aquaponics is the integration of aquaculture and hydroponics that is now being used as a model for sustainable food production. Since fresh vegetables are usually consumed raw, especially leafy greens, there are concerns about food safety and zoonotic risks from fish waste for this emerging industry. The purpose of this study was to develop an experimental recirculating aquaponic system (RAS) prototype to then investigate persistence and transfer via root uptake of an attenuated Salmonella strain in a RAS used for leafy green production. Initially, the infective dose of Salmonella enterica serovar Typhimurium strain to naïve tilapia (Oreochromis spp.) fingerlings was determined by intragastric challenge. Then, using two nonlethal doses (10⁵ and 10⁹ colony-forming units [CFU] per fish), a second group of fish was challenged and used in the laboratory-controlled RAS utilizing hydroponic lettuce. Salmonella was quantified in the system components (tanks, tubing, plant bed substrate), fish waste, and lettuce plants (roots and plants) using microbiological and molecular analysis. From the first challenge, only the three highest inoculums (10⁸–10¹⁰ CFU) yielded positive isolation of Salmonella from fish. In the second challenge, at least one of the RAS-holding Salmonella-infected fish was positive for the presence of Salmonella at the tested time points. No clinical signs or mortality were observed. On Day 42, two fish from one RAS, inoculated with a high dose (10⁹ CFU), had positive stomach and intestinal tissues with concentrations ranging from 0.36 to 160 most probable number/g of tissue. No plants or other tank system components were positive. This study describes a potential system to investigate foodborne diseases in RAS and identifies potential strategies to reduce the risk of bacterial contamination.

In Australia, circa 2019, there were an estimated 4.7 million cases of foodborne illness, resulting in costs of approximately 3 billion Australian dollars (AUD) per year. The Northern Territory (NT) is Australia’s most sparsely populated jurisdiction and has the highest proportion of Aboriginal Australians. We analyzed data on gastroenteritis outbreaks that occurred in the NT between 2005 and 2024 to describe the transmission routes, pathogens, trends and estimate costs in AUD of foodborne outbreaks. There were 408 outbreak investigations conducted between 2005 and 2024, a median of 20.5 investigations per year (range 6–35). While the annual incidence of foodborne and nonfoodborne outbreaks did not vary significantly over time, the incidence of salmonellosis outbreaks fell to 2.1 per year between 2015 and 2024 compared with 5.2 per year between 2005 and 2014 (p < 0.005). Salmonella was the most commonly identified etiological agent (73/408 outbreaks, 17.9%) followed by norovirus (45/408, 11.0%), Shigella (20/408, 4.9%), Cryptosporidium (17/408, 4.2%), and rotavirus (15/408, 3.7%). The most common outbreak transmission mode was probable person to person (146/408 outbreaks, 36%), followed by foodborne (102/408, 25%). Childcare centers were the most common settings (112/408, 27%), followed by those that occurred in the community (87/408, 21%), private residences (44/408, 10.8%), restaurants/cafes (37/408, 9.1%), and camps (23/408, 5.6%). The most common cause of foodborne outbreaks was food handler contamination (16/102, 15.6%%), followed by ingestion of contaminated raw products (15/102, 14.7%) and cross-contamination of food from raw ingredients (7/102, 6.8%). We estimated that the cost of foodborne disease outbreaks in the NT over the 20-year period was AUD 859,868 (90% uncertainty interval [UI] AUD 782,142–AUD 940,774] with a median of AUD 34,900 per year. Foodborne salmonellosis outbreaks accounted for AUD 494,360 (90% UI AUD 456,470–AUD 540,280), approximately 57% of the total cost of foodborne outbreaks.