Foodborne Pathogens and Disease

The objective of this study was to determine the minimum growth temperature of Shiga toxin–producing Escherichia coli (STEC). Forty-eight strains of STEC, including E. coli O157:H7, O104:H4, O26, O45, O103, O111, O121, and O145, were inoculated into tryptic soy broth (TSB) at ca. 6.0 CFU/mL and incubated at temperatures ranging from 5°C to 11°C. The lowest temperature at which growth occurred was determined as the minimum growth temperature of the strain. The minimum growth temperature varied among strains, but the strain difference was within 2–3°C. All of the STEC strains grew at ≥10.3°C. Majority of the STEC strains (31/48) grew at 8.9°C, with some strains (10/48) being able to grow at as low as 8.0°C. None of the STEC serogroups were able to grow at ≤7.4°C. E. coli O104:H4 and O157:H7 had relatively lower minimum growth temperatures, with 8°C and average 8.4°C, respectively, whereas serogroup O26 had a higher minimum growth temperature (average 9.6°C). The results of this study provide basic but critical information on STEC growth and could be used either in fundamental research or to mitigate the risk of STEC from food products by storing them at temperatures below the minimal growth temperature.

The six major non-O157 serogroups of Shiga toxin–producing Escherichia coli (STEC) are responsible for serious foodborne outbreaks worldwide. This research aimed to detect the six major non-O157 STEC in ground beef, artisanal dairy products, lettuce, spinach, turkey, and chicken sold in northern Morocco. Real-time polymerase chain reaction was utilized to identify the presence of the stx1, stx2, eae, wzx O26, wzx O45, wzx O103, wbdl O111, wzx O121, and ihp1 O145 genes. Out of 310 samples analyzed, Shiga toxin (stx) was detected in 55 enrichments (17.74%), stx, and eae were detected in 54/310 enrichments (17.42%), stx, eae, and genes of at least one of the six serogroups were detected in 34/310 enrichments (10.97%). Among the food matrices analyzed, ground beef showed the highest contamination rate with stx, eae, and O serogroups 13/70 (18.6%), followed by dairy 17/100 (17.00%), turkey 3/40 (7.5%), and chicken 1/40 (2.5%). No O serogroups were detected in lettuce and spinach. The most frequent serogroup was O26 (22/34; 64.7%), followed by O145 (12/34; 35.3%), O45 (12/34; 35.3%), O121 (8/34; 23.5%), O103 (8/34; 23.5%), and O111 (6/34; 17.6%). A set of 32 STEC strains were isolated from nine positive samples (9/34; 26.5%). A high rate of food contamination with STEC may indicate firstly a high public health risk due to this pathogen in beef and dairy products and secondly a lack of compliance with standard hygiene practices. Consequently, it emphasizes the urgent need for rigorous monitoring and intervention measures aimed at mitigating the incidence of STEC contamination.

As biological control agents, bacteriophages can both inhibit the pathogenic bacteria and remove the bacterial biofilms from the seafood. Vibrio cholerae is the pathogen of cholera and the severe infection could lead watery diarrhea and even death. The double-layer agar plate method was used to isolate and screen the V. cholerae bacteriophages from the samples of aquaculture water and sewage. Purified bacteriophages were examined through genome sequencing, as well as morphological and biological characterizations. Among the isolated bacteriophages, bacteriophage VC3 was found to be a long-tailed bacteriophage. Whole-genome sequencing showed that the full length of VC3 genome was 27,645 bp. It was a circular dsDNA, with 40.37% G + C content. The optimal multiplicity of infection was 1, the incubation period was 20 min, the burst period was 40 min, and the lysis volume was 73 PFU/cell. Bacteriophage VC3 exhibited good activity under low temperatures and neutral pH conditions. Bacteriophage VC3 could effectively inhibit and eliminate the biofilm of V. cholerae. In addition, bacteriophage VC3 significantly inhibited V. cholerae in fish fillets and shrimp meat. At the same time, it also showed lytic activity against 9 pathogenic bacteria, indicating that it has the potential to inhibit a variety of pathogenic bacteria.

Mastitis is among the most prevalent diseases in dairy cows, leading to substantial issues such as decreased milk yield and quality, reduced reproductive performance, early culling, and increased production costs. Staphylococcus aureus, a naturally occurring opportunistic pathogen, is majorly responsible for mastitis in dairy cows. Mammary tissues from healthy cows were used as a control group (M_C, n = 3), and mammary glands of Chinese Holstein cows infected with S. aureus (10⁵ colony-forming unit/mL) were used as experimental groups (M_S, n = 3). Histopathological examination and analysis of inflammatory factor expression confirmed the successful establishment of the mastitis model. Using label-free quantitative proteomics, we analyzed the protein expression profiles of normal healthy mammary tissues (M_C) and S. aureus-infected mammary tissues (M_S). The analysis identified 933 differentially expressed proteins in S. aureus-infected mammary tissues, with 608 upregulated and 325 downregulated proteins, compared with the healthy tissues. Gene ontology functional annotation indicated that these proteins are involved in biological processes such as oxidation–reduction, the extracellular region, and catalytic activity. The Kyoto Encyclopedia of Genes and Genomes enrichment unveiled that these proteins were associated with pathways including S. aureus infection, cell adhesion molecules, antigen processing, and presentation. According to the InterPro enrichment analysis, the immunoglobulin-like fold and pleckstrin homology domain were the most enriched structural domains. Integrated transcriptomic and proteomic analyses revealed that ETNK1 and VNN1 exhibited consistent expression trends at both the mRNA and protein levels, suggesting their potential roles as key regulators in the pathogenesis of mastitis. The results not only enhance our understanding of mastitis management at the protein level but also point the way to potential antimastitis targets.

Campylobacter spp. is a leading cause of community-acquired gastroenteritis, with rising antimicrobial resistance (AMR) posing a significant public health challenge. This study aimed to characterize the genomic basis of resistance and virulence in Campylobacter spp. isolated from human stool at the University Hospital of Split, Croatia. A total of 115 unduplicated isolates (100 Campylobacter jejuni and 15 Campylobacter coli) were identified and tested for antimicrobial susceptibility, from January to June 2023. A representative number of isolates with phenotypically detected resistance were analyzed with whole-genome sequencing. Multilocus sequence typing (MLST) was determined using genomic sequences as input data against the standard MLST schemes. High rates of resistance were detected to tetracycline (45% of C. jejuni and 26.7% of C. coli) and ciprofloxacin (81% of C. jejuni and 46.7% of C. coli), while combined ciprofloxacin/tetracycline resistance was observed in 43% of C. jejuni and 7% of C. coli isolates. The majority of whole-genome sequenced isolates possess tet(O/32/O) gene and gyrA.T861 mutation, conferring resistance to tetracycline and fluoroquinolones. All isolates have at least one resistance gene for β-lactams (bla_OXA-61, bla_OXA-193, bla_OXA-450, bla_OXA-451, bla_OXA-452, bla_OXA-461, and bla_OXA-489), while 40% of isolates possess ant(6)-Ia for aminoglycoside resistance. In addition, a newly emerged, phenotypically identified multidrug-resistant C. coli, harbored tet(O/32/O) and tet(O) genes, point mutation in gyrA gene, and A2075G mutation in 23S rRNA. Virulence analysis highlighted C. jejuni’s broad pathogenic potential, including motility, adherence, invasion, exotoxin production, and immune modulation (e.g., wlaN gene, linked to Guillain–Barré syndrome). On the contrary, C. coli isolates possess genes exclusively for motility. Nine different C. jejuni MLST sequence types were identified, while all C. coli isolates belong to the same 828 clonal complex. Escalating AMR and a broad spectrum of virulence in Campylobacter spp. highlight the importance of continuous surveillance on the phenotypic and genotypic level, thereby allowing more efficient health care management of these infections.

Toxoplasma gondii is a ubiquitous parasitic protozoan that can cause neurological and psychiatric disorders, potentially impacting human emotional behavior. This study aimed to explore serological and molecular evidence of T. gondii infection in opioid abusers in northern Iran. In this case–control study, opioid abusers who were referred to substance abuse rehabilitation centers in Mazandaran Province, northern Iran, were enrolled. Blood samples were collected from the participants to perform a serological assay to detect T. gondii IgG and IgM antibodies. A polymerase chain reaction (PCR) test was also conducted on buffy coats of the blood samples. The study comprised a total of 474 participants, with 239 individuals being opioid abusers and 235 healthy individuals serving as the control group. The results indicated that 163 opioid abusers (68.2%) were positive for T. gondii IgG, whereas 76 (31.8%) were negative. Among the control group, 63 individuals (26.8%) tested positive for T. gondii IgG, whereas 172 (73.2%) tested negative. This difference was statistically significant according to p = 0.01, odds ratio (OR) = 2.67, and 95% confidence interval (CI) = 1.03–4.15. In addition, 7.1% (17/239) of the case and 2.1% (5/235) of the control groups were PCR positive for Toxoplasma DNA. This difference was statistically significant (p = 0.01; OR = 2.96; 95%; CI = 0.94–7.01). In contrast, all of the participants were negative for T. gondii IgM antibodies. Our findings demonstrated that the sero-molecular prevalence of latent T. gondii infection in opioid abusers is significantly higher than that in healthy individuals. This suggests a potential correlation between T. gondii IgG antibody positivity and PCR results with opioid abuse.

Sarcocystis spp. are zoonotic protozoan parasites found worldwide, transmitted through the consumption of infected meat. These parasites form cysts in the muscles of livestock, causing economic losses and health risks, including reduced meat and milk production, abortions, and, in severe cases, death in intermediate hosts. This study evaluates the antiparasitic effects of nitrate and lactic acid against Sarcocystis bradyzoites in sheep meat, aiming to identify effective decontamination methods to enhance food safety. Samples of Sarcocystis cysts were collected from infected sheep organs and treated with various concentrations (3%, 6%, 9%, and 12%) of nitrate and lactic acid for 3–48 h. Bradyzoite viability was assessed microscopically after staining and digestion. Additionally, bioassays were conducted using cats to confirm the treatment’s efficacy. Results demonstrated that both compounds significantly increased bradyzoite mortality with higher concentrations and longer exposure times. Lactic acid showed greater efficacy at lower concentrations; 100% mortality was achieved at 3% lactic acid after 48 h and 6% after 24 h. In contrast, nitrate required 12% concentration for 100% mortality within 24 h. Statistical analysis revealed a significant correlation between compound concentration and exposure time with bradyzoite mortality, highlighting lactic acid’s superior antiparasitic properties at lower concentrations compared with nitrate. This study highlights the potential of lactic acid and nitrate as natural decontamination agents for meat safety. Their application could mitigate Sarcocystis-related risks, reduce foodborne parasitic infections, and contribute to the economic sustainability of meat production.

With the increase of sporadic cases of foodborne botulism and the occurrence of several large incidents of botulinum contamination in food, botulism has received greater attention in clinical practice. Foodborne botulinum toxin poisoning is an acute foodborne toxic disease caused by ingestion of food contaminated with Clostridium botulinum exotoxin. We present two cases of foodborne botulism affecting a mother and daughter who were admitted to our department after consumption of vacuum-packed rabbit-head meat. The time to symptom onset was less than 24 h in the daughter (aged 8 years) and 1 week for the mother (aged 45 years). The main clinical manifestations included fatigue, dizziness, diplopia, blurred vision, ptosis, dysphagia, and slurred speech. Blood samples tested positive for botulinum toxin type A. The daughter developed pneumonia and respiratory failure and required mechanical ventilation. Treatment measures included the use of botulinum antitoxin, fluid replacement, anti-infection, and nutritional nerve therapy. Two patients eventually recovered. When botulinum toxin poisoning is diagnosed, early administration of the appropriate antitoxin is paramount. When necessary, life support for severe cases can improve the success rate. Considering that these cases of botulism were caused by the consumption of vacuum-packed rabbit-head meat, we recommend enhancing public awareness of food safety.