Escherichia coli (E. coli) is a common pathogen that causes diarrhea in newborns and animals. Antibiotics are typically used to treat bacterial diarrhea, a global intestinal health issue. Probiotics have gained interest as a potential substitute for antibiotics in the management of E. coli-induced diarrhea and present novel therapeutic options. In this study, the probiotic properties of Lactobacillus agilis SNF7 (L. agilis SNF7) isolated from feces were investigated, and whole genome sequencing was performed to evaluate the properties of the strain. Furthermore, we investigated the protective effects of L. agilis SNF7 in a mouse model of E. coli K99 infection. L. agilis SNF7 exhibits a high survival rate in artificial gastroenteric fluid and bile salt environments, along with an antagonistic effect against E. coli O₁₁₁:K₅₈ (B₄), Staphylococcus aureus (S. aureus), and E. coli K99. Multiple genes with probiotic properties, including bacteriostasis, anti-inflammation, antioxidant, CAZyme, and the utilization of carbohydrate compounds, were identified in genome. L. agilis SNF7 prevented the gut barrier from being damaged by E. coli K99, reducing the clinical manifestations of the infection. Furthermore, L. agilis SNF7 reduced the expression of inflammatory cytokines (IL-6, IL-1β, and TNF-α) by inhibiting the phosphorylation of proteins linked to the NF-κB and MAPK signaling pathways. L. agilis SNF7 improved the intestinal microbial barrier, controlled the balance of the intestinal microecology, and reduced the entry of harmful microbes into the intestine. By controlling gut flora and reducing the inflammatory response, L. agilis SNF7 may be able to prevent and treat E. coli K99 infections. The application of L. agilis SNF7 in the creation of probiotic formulations to stop intestinal illnesses brought on by E. coli infections is clarified by this work.

Dairy cows are highly susceptible to mastitis caused by Klebsiella pneumoniae, and treating these infections poses a challenge due to the resistance of the bacterium to common antibiotics. This study aimed to evaluate the safety of W. cibaria SDS2.1 and investigate its protective effects against K. pneumoniae-induced mastitis. The safety of W. cibaria SDS2.1 was assessed through comprehensive analyses, including antibiotic resistance profiling, hemolysis assays, cell cytotoxicity tests, and whole-genome sequencing. Furthermore, its ability to protect against cellular and tissue damage caused by K. pneumoniae-induced mastitis was evaluated using both in vitro and in vivo models. Our results revealed that W. cibaria SDS2.1 was non-hemolytic, non-cytotoxic, and significantly inhibited the growth of K. pneumoniae (p < 0.05). Additionally, W. cibaria SDS2.1 effectively reduced the adhesion and invasion of K. pneumoniae. In the K. pneumoniae-induced mouse mastitis model, W. cibaria SDS2.1 significantly reduced myeloperoxidase (MPO) activity, mammary tissue damage, and the expression of inflammatory cytokines (IL-6, IL-1β, and TNF-α) (p < 0.05). In K. pneumoniae-infected bovine mammary epithelial cells (bMECs), W. cibaria SDS2.1 significantly decreased lactate dehydrogenase (LDH) release, indicating reduced cellular damage. These findings demonstrate that W. cibaria SDS2.1 exhibits anti-inflammatory properties in experimental models, suggesting its potential role in mitigating K. pneumoniae-induced mastitis.

Bovine mastitis, mainly caused by contagious pathogens like Staphylococcus aureus , Streptococcus agalactiae , and Mycoplasma bovis , environmental pathogens such as Escherichia coli , Streptococcus uberis , Klebsiella pneumoniae , and a more opportunistic pathogen like Streptococcus dysgalactiae , severely threatens dairy production. These mastitis pathogens rely on their respective virulence characteristics to exert different inflammation of the mammary gland. Meanwhile, antimicrobials remain the primary treatment for bovine mastitis, but growing resistance often causes failure. Therapeutic approaches targeting the virulence factors utilized by these mastitis-causing pathogens are expected to become effective alternatives to antimicrobial therapy in dairy farming. Therefore, the objective of this review is to investigate the prevalence and pathogenic roles of virulence genes in mastitis pathogens, with an extensive exploration of the emerging vaccination approaches targeting the virulence factors for safeguarding dairy animal health.

K. pneumoniae is a major cause of bovine mastitis worldwide, making it difficult to control due to its resistance to multiple drugs. L. paraplantarum has been explored as a promising new approach to fighting bovine mastitis. In this study, the probiotic potential and safety of L. paraplantarum SDN1.2, as well as its ex vivo and in vivo anti-inflammatory effects against K. pneumoniae-induced mastitis, were comprehensively investigated using bioinformatics analyses and experimental validation methods. The results revealed that L. paraplantarum SDN1.2 exhibits non-hemolytic activity, is not cytotoxic, lacks virulence genes (e.g., adhesion factors, toxins, and invasion factors) and antibiotic resistance genes (e.g., beta-lactamases and tetracycline resistance genes), as supported by whole-genome sequencing, and significantly inhibits the growth of K. pneumoniae, as evaluated by antimicrobial tests. Following further validation in vitro, L. paraplantarum SDN1.2 demonstrated the capability to inhibit the adhesion and invasion of K. pneumoniae to bMECs. In a mouse model of K. pneumoniae-induced mastitis, L. paraplantarum SDN1.2 reduced the extent of neutrophil infiltration and inflammatory lesions. Furthermore, L. paraplantarum SDN1.2 pretreatment significantly reduced myeloperoxidase (MPO) activity and the expression of inflammatory cytokines (IL-6, IL-1β, and TNF-a) in mouse mammary gland tissue. In K. pneumoniae-infected bMECs, L. paraplantarum SDN1.2 significantly lowered lactate dehydrogenase (LDH) levels and expression of inflammatory cytokines such as IL-6, IL-1β, and TNF-α. The results demonstrated that the newly isolated L. paraplantarum SDN1.2 from bovine sources exhibits promising characteristics as a safe probiotic for the alleviation of bovine mastitis due to its safety profile and anti-inflammatory and antibacterial properties.

The calcium requirements of dairy cows increase dramatically soon after calving, and many cows have subclinical hypocalcemia, adversely affecting health and performance. Traditional laboratory tests for calcium are complex and not easily adapted to rapid point-of-care applications. The objectives were to evaluate a portable iCa testing device, Horiba LAQUAtwin Ca-11C, for measuring ionized calcium (iCa) in the whole blood of dairy cows and to investigate the iCa-to-total-calcium (tCa) ratio in blood collected from dairy cows within 9 days after calving. This study was conducted on two large dairies in northern China. First, blood samples were collected from 246 cows within 3 days after calving, and whole-blood iCa concentrations were measured with a Horiba LAQUAtwin Ca-11C and Abbott i-STAT 1. In addition, 885 blood samples were collected from 102 dairy cows between calving and 9 days postpartum, with iCa concentrations measured using a Horiba LAQUAtwin Ca-11C and tCa concentrations determined by a fully automated biochemical analyzer. The Horiba LAQUAtwin Ca-11C and Abbott i-STAT 1 had significant consistency in the measurement of ionized calcium concentration in whole blood (the frequency of differences between the measured values was within ±20% of the average, reaching 95.53%), and the measurement results of the two instruments were correlated (Deming regression analysis R² = 0.87). This implied the potential application of the Horiba LAQUAtwin Ca-11C as a simplified device for measuring iCa in dairy farms for on-site testing. Within the first 9 days after calving, the ratio of ionized calcium to total calcium fluctuated but overall remained within the range of 44.2 to 47.22%. Furthermore, significant variations in the ratio among individual cows indicated that individual differences and physiological states of cows affected calcium metabolism. This study identified the potential to use the Horiba LAQUAtwin Ca-11C for point-of-care testing on dairy farms. Nevertheless, the impacts of factors such as health status and individual cow differences on the ratio of ionized calcium to total calcium still require further investigation.

Objective: The objective of this study was to evaluate the function of the reactive oxygen species (ROS)-mitochondrial pathway in attenuating Escherichia coli (E. coli) induced apoptosis in bovine endometrial epithelial cells (BENDs) by Lactobacillus rhamnosus (L. rhamnosus) GR-1.Methods: The BENDs were exposed to preincubation with and without L. rhamnosus GR-1 for 3 hours (h) and they were later subject to E. coli for 6 h. The release of lactate dehydrogenase (LDH), the expression of oxidative factors, adhesion and invasion of E. coli, the expression of mitochondrial membrane potential (MMP), apoptotic rate and apoptosis-associated protein expression were observed. Then, ROS expression, MMP level and cell rate apoptosis rate were further detected after the intervention of antioxidant n-acetyl-l-cysteine (NAC).Results: L. rhamnosus GR-1 was capable of obviously alleviating the content of LDH, ROS expression, E. coli adhesion and invasion, the apoptotic rate and MDA concentrations in BENDs induced by E. coli (p<0.01). In addition, L. rhamnosus GR-1 could notably promote the levels of antioxidant factors (SOD, GSH, T-AOC) (p<0.01), inhibit the depolarization of MMP (p<0.01), and levels of apoptosis-related factors (Bax, Caspase-3 and Cyt-c), and promote anti-apoptosis factor (Bcl-2) (p<0.01). Moreover, after the intervention of antioxidant NAC, ROS expression, MMP depolarization, and apoptotic rate induced by E. coli in BENDs were decreased (p<0.01).Conclusion: In E. coli-induced apoptosis in BENDs, therapeutic strategies aimed at down-regulating ROS and MDA and up-regulating antioxidant factors may maintain mitochondrial function and provide theoretical support for the use of probiotics in bovine endometritis.