Bacillus cereus is a common and ubiquitous foodborne pathogen with an increasing prevalence rate in dairy products in China. High and unmet demands for such products, particularly milk, raise the risk of B. cereus associated contamination. The presence of B. cereus and its virulence factors in dairy products may cause food poisoning and other illnesses. Thus, this review first summarizes the epidemiological characteristics and analytical assays of B. cereus from dairy products in China, providing insights into the implementation of intervention strategies. In addition, the recent achievements on the cytotoxicity and mechanisms of B. cereus are also presented to shed light on the therapeutic options for B. cereus associated infections.

Subclinical mastitis is a common disease that threatens the welfare and health of dairy cows and causes huge economic losses. Somatic cell count (SCC) is the most suitable indirect index used to evaluate the degree of mastitis. To explore the relationship between SCC, diversity in the microbiome, and subclinical mastitis, we performed next-generation sequencing of the 16S rRNA gene of cow’s milk with different SCC ranges. The data obtained showed that the microbiota was rich and coordinated with SCC below 2 × 10⁵. SCC above 2 × 10⁵ showed a decrease in the diversity of microbial genera. When SCC was below 2 × 10⁵, the phylum Actinobacteriota accounted for the most. When SCC was between 2 × 10⁵ and 5 × 10⁵, Firmicutes accounted for the most, and when SCC exceeded 5 × 10⁵, Firmicutes and Proteobacteria accounted for the most. Pathogenic genera such as Streptococcus spp. were absent, while SCC above 2 × 10⁵ showed a decrease in the diversity of microbial genera. SCC was positively correlated with the percentage of Romboutsia, Turicibacter, and Paeniclostridium and negatively correlated with the percentage of Staphylococcus, Psychrobacter, Aerococcus, and Streptococcus. Romboutsia decreased 6.19 times after the SCC exceeded 2 × 10⁵; the SCC increased exponentially from 2 × 10⁵ to 5 × 10⁵ and above 1 × 10⁶ in Psychrobacter. Analysis of the microbiota of the different SCC ranges suggests that the development of mastitis may not only be a primary infection but may also be the result of dysbiosis in the mammary gland.

The active components, potential targets, and mechanisms of action of oregano essential oil in the treatment of bovine mastitis disease were investigated using network pharmacology and molecular docking approaches. The TCMSP and literature databases were examined for the main compounds in oregano essential oil. Afterward, the physical, chemical, and bioavailability characteristics of the components were evaluated. The PubChem, BATMAN, PharmMapper, and Uniprot databases were utilized to predict the target genes of the major components of oregano essential oil. Via the databases of DrugBank, OMIM, GeneCards, TTD, and DisGenet, the disease targets of bovine mastitis were discovered. We analyzed common targets and built protein–protein interaction (PPI) networks using the STRING database. Key genes were analyzed, obtained, and compound–target–pathway–disease visualization networks were created using Cytoscape. For the GO function and KEGG pathway enrichment analysis, the DAVID database was utilized. Molecular docking via Autodock Tools was utilized to evaluate the reliability of the interactions between oregano essential oil and hub targets. Thymol, carvacrol, and p-cymene are the three major components found in oregano essential oil. The potential targets (TNF, TLR4, ALB, IL-1β, TLR2, IL-6, IFNG, and MyD88) were screened according to the visual network. The enrichment analysis suggested that the major signaling pathways in network pharmacology may include PI3K-Akt, MAPK, IL-17, and NF-κ B. Molecular docking analysis shows that thymol had good docking activity with TNF, IL-6, and MyD88, carvacrol had good docking activity with TNF, and p-cymene had good docking activity with ALB. This study clarified the mechanism of action of oregano essential oil in the treatment of bovine mastitis, thus providing data supporting the potential for the use of oregano essential oil in the development of new therapeutics for bovine mastitis.

Salmonella Thompson, an important foodborne pathogen, is rarely found to be pathogenic to poultry. Accidentally, S. Thompson was found to be pathogenic to embryos of white feather broiler at a poultry farm in China. Therefore, this study aimed to explore antimicrobial resistance and pathogenicity of clinical S. Thompson isolated from dead poultry embryos. The phylogenetic tree based on 16S rRNA and seven housekeeping genes showed that the 14 clinical S. Thompson were closely related. The core-genome multilocus sequence typing of 14 clinical S. Thompson based on whole-genome sequencing was cgST-12774, consistent with the only two strains of S. Thompson from humans in China as reported in the NCBI database. The antimicrobial resistance gene analysis demonstrated that all strains carried aac(6′)-Iaa and the polymyxin resistance gene mcr-9. Antimicrobial sensitivity tests for 18 antibiotics showed that S. Thompson isolates displayed resistance against streptomycin (100%), ampicillin (35.7%), and doxycycline (14.3%), but sensitivity to polymyxin B, proving that the mcr-9 gene had not appeared resistance phenotype. Virulence genes Salmonella pathogenicity island (SPI) SPI1-5, type I fimbriae gene (fimA), flagellar assembly genes (bcfC, flhD, fliA, fliC, fljB, flgK, and lpfC), and other virulence genes (iroN, pagC, and cigR) were found in each S. Thompson isolate. Additionally, the bacterial inoculation experiment with 1-day-old chicks revealed that clinical S. Thompson was highly pathogenic to newborn chicks after yolk sac inoculation. This study highlighted that the S. Thompson isolated from poultry embryos and the S. Thompson causing human foodborne diarrhea in some parts of China belong to the same cgMLST typology (cgST-12774) and showed the pathogenicity of this clinical S. Thompson to chicks.

Chlorine dioxide is a globally recognized green and efficient disinfectant. This study aims to investigate the bactericidal mechanism of chlorine dioxide using beta-hemolytic Streptococcus (BHS) CMCC 32210 as a representative strain. BHS was exposed to chlorine dioxide, the minimum bactericidal concentration (MBC) values of chlorine dioxide against BHS were determined by the checkerboard method in preparation for subsequent tests. Cell morphology was observed using electron microscopy. Protein content leakage, adenosine triphosphatase (ATPase) activity, and lipid peroxidation were determined by kits, and DNA damage was determined using agar gel electrophoresis. The concentration of chlorine dioxide during disinfection showed a linear relationship with the concentration of BHS. Scanning electron microscopy (SEM) results showed that chlorine dioxide caused significant damage to the cell walls of BHS at a concentration of 50 mg/L, but had no significant effect on Streptococcus exposed to different exposure times. Furthermore, the extracellular protein concentration increased with increasing chlorine dioxide concentration, while the total protein content remained unchanged. The activities of Na⁺/K⁺-ATPase and Ca²⁺/Mg²⁺-ATPase decreased with increasing chlorine dioxide concentration. Chlorine dioxide treatment led to significant lipid peroxidation and DNA degradation in BHS. Leakage of intracellular components indicated that chlorine dioxide damaged the cell membrane of BHS. Chlorine dioxide exposure resulted in oxidative damage to lipids and proteins, which negatively impacted the cell wall and membrane of Streptococcus. This caused increased permeability and inactivation of key enzymes (Na⁺/K⁺-ATPase and Ca²⁺/Mg²⁺-ATPase) involved in respiratory metabolism, ultimately leading to DNA degradation and bacterial death due to either content leakage or metabolic failure.

The poultry red mite (PRM), Dermanyssus gallinae, a significant ectoparasite causing diseases in poultry, is globally prevalent and necessitates effective control strategies. There are restrictions on the use of acaricides in poultry across several nations due to worries about medication residues. Consequently, finding safe and efficient treatments for PRM is imperative. Fluralaner solution has emerged as a potential therapeutic agent, distinguished by its rapid onset, enduring efficacy, and lack of a withdrawal period for egg production. To ascertain the optimal dosage and therapeutic efficacy of fluralaner solution in PRM treatment, this study evaluated blood biochemical parameters and mite populations across various treatment groups. A cohort of 500 laying hens was randomly assigned to one of five treatment groups, each comprising 100 individuals:high-dose group (0.1 ml/kg-bw, group 4 ×, coop 1), medium-dose group (0.05 ml/kg-bw, group 2 ×, coop 5), low-dose group (0.025 ml/kg-bw, group 1 ×, coop 2), drug-control group (Intervet Productions, 0.05 ml/kg-bw recommended dose, coop 3) and blank control group (coop 4). Hens received their respective dosages of the fluralaner solution via oral administration on Days 0 (D0) and 7 (D7) of the experimental period. Over the study's ninety days, blood biochemical markers and mite counts in each coop were measured to evaluate the drug's safety, effectiveness, and ideal dosage. Data analysis was performed utilizing SPSS software. The study findings indicated that, for effective PRM infestation treatment, a dosage of 0.5 mg fluralaner per kilogram of body weight (equivalent to 0.05 ml) administered daily, followed by a subsequent dose post a 7-day interval, is recommended. Additionally, clinical observations coupled with blood biochemical assessments confirmed the safety of fluralaner across the three tested dosage levels in hens.