Search Results (463)

Subclinical bovine mastitis (SBM) is an inflammatory condition of the udder that remains a major concern for the dairy industry due to its high incidence and the direct and indirect associated costs. Antibiotics are widely used for prophylaxis and therapy in livestock, especially for SBM. However, overuse and misuse have contributed to the emergence of antimicrobial resistance (AMR), enabling resistant bacteria to enter the food chain and potentially spread to humans. This study aimed to detect antibiotic-resistant Staphylococcus and Streptococcus associated with SBM in dairy cows from Pioter, north-central Ecuador. For this, a commercial screening test, morphological and biochemical assays, standard culture techniques, mass spectrometry, and PCR (polymerase chain reaction) were applied. Among 99 isolates, 77 were Staphylococcus and 22 were Streptococcus. Among the identified Staphylococcus isolates, S. aureus was the predominant species (36.4%). Resistance in Staphylococcus exceeded 70% for fosfomycin and was under 30% for the other antibiotics tested. In Streptococcus, S. uberis predominated (54.5%), with resistance primarily to penicillin and tetracycline (>50%). PCR identified mecA, nuc, and lukSF-PV genes in 7.8%, 29.9%, and 6.5% of Staphylococcus isolates, respectively. In Streptococcus, the ermB and blaZ genes were found in 18.2% and 50% of isolates, respectively. These data provide a baseline on SBM-associated AMR in the study area and highlight the need for ongoing surveillance and improved milking practices to mitigate risks to the dairy sector and public health. Full article

Enterococci are among the most frequently isolated environmental bacteria that cause mastitis in cows. This study aimed to determine the prevalence of virulence genes, as well as phenotypic and genotypic antibiotic resistance, among eighty enterococcal isolates from cases of bovine mastitis in Polish herds. The presence of virulence and antibiotic resistance genes was determined by PCR. E. faecalis isolates were found to carry more virulence genes than E. faecium isolates, including the efaA_fs (100%), ace (98.1%), gelE (86.5%), asa1 (63.5%), esp (57.7%) and cylA (17.3%) genes. The efaA_fm gene was the only virulence gene detected in E. faecium isolates. This study revealed that E. faecalis showed a higher virulence gene burden. The ermB gene was present in 90.9% of the Enterococcus spp. that were phenotypically resistant to erythromycin. Almost all tetracycline-resistant Enterococcus isolates carried the tet(M) gene (94.3%), either alone or in combination with the tet(L) and tet(O) genes. Three isolates harboured vanC genes and were susceptible to vancomycin (MIC = 4 μg/mL). The results confirm the high level of antimicrobial resistance of enterococci isolated from cows with mastitis and indicate the genes that may be responsible for this resistance. Full article

Streptococcus agalactiae is a major contagious pathogen of bovine mastitis and causes substantial economic losses in the dairy industry. In this study, a dual-readout RPA-PfAgo detection platform targeting the conserved cfb gene of S. agalactiae was established and optimized. Seven pairs of RPA primers were designed and screened to construct the Basic-RPA assay, and six guide DNAs (gDNAs) together with a specific probe were evaluated for PfAgo-assisted detection. Field validation was performed using 153 bovine milk samples collected from five dairy-farming regions in China, and assay performance was compared with bacteriological culture and a standardized quantitative PCR (qPCR) assay. The Basic-RPA assay achieved optimal amplification at 37 °C for 30 min, with a detection limit of 1 × 10⁻³ ng/µL and no cross-reactivity with non-target bacteria. The optimized RPA-PfAgo-RTF assay detected as few as 10 copies/µL, whereas the RPA-PfAgo-LFD assay detected 100 copies/µL, and both formats showed high analytical specificity. In field milk samples, bacteriological culture detected 21 positive samples, whereas standardized real-time PCR (qPCR), RPA-PfAgo-RTF, and RPA-PfAgo-LFD each detected 33 positive samples. When compared with bacteriological culture as a conventional comparator, all three molecular assays showed 100.00% positive agreement, 90.91% negative agreement, and a Kappa value of 0.733. In addition, RPA-PfAgo-RTF and RPA-PfAgo-LFD were completely concordant with the standardized qPCR assay across all 153 samples. These results indicate that the dual-readout RPA-PfAgo platform is a rapid and reliable molecular tool for detection of S. agalactiae in bovine milk. Full article

Mastitis is one of the most prevalent diseases in dairy cows, leading to significant economic losses and increased antibiotic usage. The development of safe and effective alternatives is therefore urgently needed. In this study, we investigated the protective effects of Forsythiaside A (FTA), a natural compound, against LPS-induced mastitis in bovine mammary epithelial (MAC-T) cells and a murine model. FTA significantly reduced intracellular reactive oxygen species (ROS), decreased lipid peroxidation, and restored antioxidant capacity. Furthermore, FTA increased the expression of GPX4 and SLC7A11, indicating inhibition of ferroptosis. The ferroptosis inducer RSL3 partially reversed these protective effects, supporting the involvement of GPX4-associated ferroptosis regulation in the protective effects of FTA. In vivo, FTA alleviated mammary tissue injury, reduced inflammatory cell infiltration, and improved redox balance. These findings suggest that FTA may serve as a potential natural therapeutic agent for mastitis, providing a promising alternative to antibiotic-based treatments in dairy production. Full article

Medicinal plants have attracted increasing scientific interest due to the diversity of bioactive compounds reported across different species. They may represent complementary sources of bioactive compounds alongside conventional antimicrobials, which may pose risks to animal health and compromise treatment efficacy. Considering the importance of alternative compounds, we aimed to evaluate the antimicrobial activity in vitro of medicinal plants Stryphnodendron adstringens (Mart.) Coville, known as barbatimão, Baccharis crispa Spreng, known as carqueja and Azadirachta indica, known as neem. S. adstringens (Mart.) Coville and B. crispa Spreng were used as extract and obtained from plants collected in the municipality of Bambuí, state of Minas Gerais, Brazil. A. indica was evaluated as extract and oil, and the crushed leaves and oil were purchased from a commercial company. Antimicrobial activity was determined by the minimum bactericidal concentration (MBC) test-against Staphylococcus aureus, Streptococcus agalactiae, Streptococcus uberis, Escherichia coli, and Salmonella spp., isolated from bovine mastitis. The bacteria were submitted to the MBC test at concentrations of 100, 50, 25, 12.5, 6.25, 3.12, 1.56, 0.78, 0.39, 0.19 and 0.09 mg/mL. The bacteria evaluated were sensitive to most plant extracts for at least one of the concentrations evaluated, except for Gram-negative bacteria, Escherichia coli, and Salmonella spp. There was no activity of B. crispa Spreng extract and A. indica against E. coli and neither of B. crispa Spreng extract against Salmonella spp. even at the highest concentration evaluated. S. adstringens (Mart.) Coville was considered the extract with the highest activity against the bacteria evaluated and S. uberis the most susceptible to antimicrobial action. The results indicate detectable antimicrobial activity of the evaluated extracts and oil, suggesting their potential relevance as complementary sources of bioactive compounds for further investigation, rather than as direct alternatives to conventional antibiotic therapies. Paper spray mass spectrometry (PS-MS) was employed as an exploratory phytochemical screening approach, and all metabolite assignments reported herein should be regarded as tentative or putative annotations under the analytical conditions used, consistent with MSI Level 3 confidence. Full article

Bovine mastitis is a persistent and challenging illness in dairy industry, bringing about devastating economic losses to the sector. The longstanding over-reliance on antibiotic therapy has raised severe public health concerns, highlighting the critical need to develop safe and effective alternative regimens. Pulsatilla saponin B4 (PSB4), a plant-derived triterpenoid saponin, has been shown to regulate inflammation. However, the effect of PSB4 on mastitis in lactating cows has not been elucidated. The aim of this study was to explore the anti-inflammatory property and the molecular mechanisms of PSB4 in bovine mammary epithelial cells (BMECs) and mouse mastitis model. In cultured cells, PSB4 alleviated LPS-induced inflammatory reaction by suppressing the expression of pro-inflammatory mediators in BMECs. Notably, RNA-seq analysis indicated that the anti-inflammatory effect of PSB4 was correlated with IL-17RA and NF-κB signaling, with subsequent Western blot validation. Moreover, BMECs were stimulated with recombinant interleukin-17A (rIL-17A) to induce inflammation and challenged with Taltz to specifically inhibit IL-17RA signaling. The results showed that PSB4 reversed the rIL-17A-induced upregulation of elements within the IL-17RA pathway and its downstream MAPK/NF-κB cascade, including their downstream effectors. Furthermore, Taltz blocked the efficacy of PSB4 in protecting against LPS-induced inflammation. In vivo, PSB4 alleviated the inflammatory damage of mammary gland, pro-inflammatory mediator levels in mammary gland tissue and se-rum, while blocking the activation of IL-17RA signal along with downstream MAPK/NF-κB signal in LPS-induced mouse mastitis model. Taken together, studies in both BMECs and mice demonstrated that PSB4 alleviates mastitis by inhibiting IL-17RA signaling and downstream MAPK/NF-κB pathway, which may be a new strategy and a target for the management of mastitis. Full article

Bovine mastitis remains a major impediment to optimal dairy production. Somatic cell count (SCC) is commonly used as an indicator of mammary gland inflammation, while milk microbiota may also reflect mastitis-related changes. Here, we employed Oxford Nanopore full-length transcript sequencing to delineate the peripheral blood transcriptomic landscape of Xinjiang Brown cattle stratified by high (SCC ≥ 1,000,000 cells mL⁻¹) and low (SCC ≤ 200,000 cells mL⁻¹) SCCs, with the objective of identifying candidate genes underpinning mastitis resistance. We identified 226 differentially expressed genes and 441 differentially expressed transcripts. Genes in the high-SCC group were prominently enriched in immune response pathways and chemokine signalling cascades. Protein–protein interaction network analysis further delineated a core module of ten immune-related genes, including CCL4, IL1B and CXCL2. Integrative analysis with complementary second-generation sequencing data pinpointed CXCL2 as a high-priority candidate. Subsequent RT–qPCR and enzyme-linked immunosorbent assay (ELISA) validation revealed that CXCL2 expression was significantly elevated both in high-SCC individuals and in an LPS-induced bovine mammary epithelial cell inflammation model. Collectively, these findings establish CXCL2 as a putative molecular marker for mastitis resistance breeding and provide a foundational resource for deciphering the molecular mechanisms governing mammary health. Full article

Staphylococcus aureus (S. aureus) bovine mastitis is a significant public health issue. Despite enormous efforts, important gaps remain regarding host–microenvironmental factors. How intramammary reduced oxygen modulates S. aureus transcription in bovine mammary epithelial cells (MECs) remains unclear. We examined oxygen-associated transcriptional changes in a bovine-mammary adapted S. aureus clone following internalization into MECs and identified functional category enrichments under Normal-O₂ and Reduced-O₂ exposures. Bovine MAC-T monolayers were infected with a dominant bovine mastitis isolate under Normal-O₂ or Reduced-O₂ conditions. Triplicate infection experiments were performed for each oxygen condition. Each condition included matched non-reacted bacterial controls maintained under the same gas condition but without MAC-T exposure serving as the reference condition for expression calling. RNA was extracted and profiled using a high-throughput qRT-PCR platform covering genome-wide loci. Expression calls were mapped to curated BioQT roles and interpreted descriptively. Results indicated 211 loci were upregulated and 99 were downregulated under Normal-O₂ conditions, versus 53 upregulated and 35 downregulated under Reduced-O₂ conditions, relative to their non-reacted controls. Under Normal-O₂ conditions, regulated loci covered multiple functional roles, including cellular processes, transport/binding proteins, regulatory functions, and energy metabolism with downregulated loci enriched in transport/binding and cell-envelope categories. Under Reduced-O₂ conditions, upregulated loci were abundant in cellular process annotations dominated by pathogenesis/toxin-related functions, whereas downregulated loci were enriched in nucleotide biosynthetic and DNA/cell division categories. Thus, this reveals oxygen-associated shifts in the transcriptional response of intramammary S. aureus in MAC-T cells. Normal-O₂ conditions were associated with broader category representation, whereas Reduced-O₂ conditions yielded a narrower distribution enriched for selected toxin/pathogenesis- and iron/cation-associated annotations. These oxygen-linked transcriptional-shifts highlight candidate pathways for the intramammary adaptation of S. aureus, potential diagnostic markers, anti-virulence strategies, and targeted therapeutics. Full article

Bovine mastitis is a major infectious disease in dairy cattle, causing significant economic losses and compromising animal health and milk quality worldwide. Among its etiological agents, Staphylococcus aureus is a key contagious pathogen due to its ability to establish persistent intramammary infections and evade host immune responses and antimicrobial therapy. This review summarizes current knowledge on the epidemiology, pathogenesis, clinical presentation, diagnosis, and control of S. aureus in bovine mastitis. Particular emphasis is placed on virulence mechanisms, including adhesion, intracellular persistence, biofilm formation, and immune evasion, which contribute to chronic and recurrent infections. The increasing prevalence of antimicrobial resistance, including methicillin-resistant and multidrug-resistant strains, is highlighted as a major challenge limiting treatment efficacy and posing risks within a One Health context. The review also discusses emerging alternative therapies and innovative control strategies, such as anti-biofilm approaches, immunomodulation, and improved diagnostics, aimed at reducing antimicrobial use. Advances in molecular and point-of-care diagnostic tools are considered for their role in early detection and targeted interventions. Overall, effective control of S. aureus mastitis requires integrated strategies combining prudent antimicrobial use, alternative therapies, improved hygiene, and a multidisciplinary One Health approach. Full article

Antimicrobial resistance in bovine mastitis pathogens poses interconnected threats to dairy productivity and public health; however, longitudinal evidence on the association between veterinary oversight and lower resistance to critically important antimicrobials in tropical smallholder systems remains limited. This study analyzed 1347 quarter milk samples from 47 dairy farms in Saraburi Province, Thailand, submitted consecutively over five years (2020–2025), to evaluate whether participation in a veterinary-led herd health (HH) program was independently associated with reduced vancomycin resistance and multidrug resistance (MDR). Bacterial identification was conducted using standard methods, and susceptibility was determined using the Kirby–Bauer disk diffusion method. Among 1069 culture-positive samples, Streptococcus spp. (25.3%) and coagulase-negative staphylococci (16.8%) predominated. Vancomycin resistance declined from 15.9% to 5.4% between early (2020–2022) and recent (2023–2025) periods. Of the 686 isolates tested against ≥3 antibiotic classes, 61 (8.9%) were MDR; vancomycin resistance co-occurred in 34.4% of these samples. Repeated logistic regression identified non-HH farm status (OR = 4.035; p = 0.027) and early-year groups (OR = 4.611; p = 0.002) as independent risk factors for vancomycin resistance. As HH participation and year group showed a significant interaction, their joint effect for MDR was modeled: compared with non-HH farms in the early period (reference), all other combinations—including HH farms in 2023, HH farms in 2020, and non-HH farms in 2023—were associated with significantly lower odds of MDR. These findings provide the first evidence from Thailand that structured veterinary herd health programs are independently associated with lower critically important antimicrobial resistance, supporting their integration into a One-Health stewardship policy. Full article

Enterococcus lactis is increasingly recognized as an emerging mastitis pathogen, yet the functional basis of its virulence and associated health risks remain poorly defined. This study presents an integrated genomic and phenotypic characterization of E. lactis strain EL-A150 isolated from bovine subclinical mastitis. Whole-genome sequencing revealed a 2.49 Mb circular chromosome encoding multiple genes associated with adhesion (acm, bepA, fms, sagA), biofilm formation (empB, empC) and antimicrobial resistance, including determinants related to aminoglycosides and macrolides. Phenotypic assays demonstrated rapid growth, strong biofilm-forming capacity and high adhesion to bovine mammary epithelial cells, while internalization remained low and intracellular persistence was transient. Comparative genomic analyses confirmed the taxonomic placement of the strain within the E. lactis clade (ANI up to 99.5% against reference genomes) and revealed a limited resistome composed of chromosomally encoded genes, with no detectable plasmids or major mobile genetic elements. Collectively, these findings demonstrate that E. lactis EL-A150 possesses a coordinated set of traits conducive to intramammary colonization, supporting its classification as an opportunistic pathogen. The convergence of virulence potential and clinically relevant antimicrobial resistance within a single isolate underscores a One Health concern and highlights the need for surveillance frameworks that integrate functional validation with genomic risk assessment. Full article

Bovine mastitis causes significant economic losses in the dairy industry. Emerging evidence highlights the critical role of long non-coding RNAs (lncRNAs) in inflammation-associated epigenetic regulation through competing endogenous RNA (ceRNA) networks. In this study, we established a bovine mastitis model in three healthy primiparous Holstein cows by intramammary infection with S. aureus. Infected and control mammary tissue samples were then collected for transcriptomic profiling, which identified 2005 differentially expressed lncRNAs. Among them, BMNCR was significantly upregulated in S. aureus-infected mammary tissues and S. aureus-stimulated BMECs. We evaluated the coding potential of BMNCR and confirmed its non-coding nature. Functional studies in BMECs demonstrated that knockdown of BMNCR suppressed proliferation, promoted apoptosis, and altered the expression of inflammatory factors, including IL-2, IL-6, IL-8, and IL-12. Mechanistically, BMNCR acted as a sponge for bta-miR-145, thereby leading to the derepression of ANO6. Silencing ANO6 partly recapitulated the effects of BMNCR knockdown, impairing proliferation and increasing IL-8 expression. Collectively, these findings suggest that the BMNCR/miR-145/ANO6 axis is involved in the regulation of inflammatory responses and epithelial homeostasis during bovine mastitis, with BMNCR functioning as a protective regulator in this process. Full article

The growing problem of antibiotic resistance poses one of the greatest threats to modern medicine, making the search for new, alternative strategies to treat bacterial infections a matter of priority. The aim of the study was to evaluate the antimicrobial activity of selected postbiotic substances (PS) and nisin against methicillin-susceptible (MS) and methicillin-resistant (MR) strains of coagulase-negative staphylococci (NAS) and mammaliicocci. The study was conducted on 24 strains of coagulase-negative staphylococci and mammaliicocci isolated from milk collected from Holstein-Friesian (HF) cows with subclinical mastitis. In vitro, PS/EMo (100–400 AU/mL) and PS/Eas (100–200 AU/mL) were the most effective, inhibiting the growth of all MS and MR strains of NAS and Mammaliicoccus spp. (100.0%). A high percentage of strains were also sensitive to postbiotic substances produced by Lactococcus lactis subsp. lactis PS/MK2/8 (400–1600 AU/mL), PS/MK1/3 (100–400 AU/mL), and nisin (100–25,600 AU/mL), both in MR strains (94.1%, 82.4%, 88.2%, respectively) and in MS strains (100.0%, 85.7% and 100%, respectively). PS/Esach (100–25,600 AU/mL) inhibited the growth of all strains, including the mecA gene-positive mammaliicocci strains (100.0%), but was slightly less effective against the MS strains (64.7%). The lowest activity was observed with postbiotic substances produced by Enterococcus faecium, PS/4231 (100–1600 AU/mL) and PS/9296 (100–6400 AU/mL), which inhibited the growth of 3 out of 17 MR strains (17.65%). Among the Mammaliicoccus strains with the mecA gene, postbiotic substances derived from strains PS/4231 and PS/9296 inhibited the growth of 42.9% and 28.6% of the strains, respectively. Four tested strains were sensitive to all postbiotic substances (MSC9, MSC11, MSC12 and SCH3). This study confirms that postbiotic substances and nisin inhibit the growth of staphylococci isolated from the milk of cows with subclinical mastitis, including methicillin-resistant strains. Full article

Streptococcus agalactiae, also known as Group B Streptococcus (GBS), is a major pathogen responsible for mastitis in dairy cows. It causes persistent and difficult-to-treat mammary infections, leading to reduced milk production. Baicalein, a flavonoid compound, exhibits anticancer, anti-inflammatory, and antibacterial activities; however, its specific mechanism of action against GBS remains unclear. This study aimed to investigate the mechanism by which baicalein inhibits GBS invasion of bovine mammary epithelial cells (bMECs). The results showed that baicalein at concentrations of 4 μg/mL or higher effectively inhibited 50% of the invasion of bMECs by GBS strain HB31 and exerted a concentration-dependent inhibitory effect on bacterial adhesion. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of baicalein against HB31 were both greater than 1024 μg/mL. Therefore, the antibacterial effect of baicalein alone may not fully account for its mechanism; other pathways likely contribute to the reduced invasiveness of GBS. To elucidate the mechanism by which baicalein inhibits GBS invasiveness, this study investigated both bacterial metabolism and gene expression. Metabolomic analysis revealed that baicalein treatment led to the downregulation of amino acid metabolites, including alanine and aspartic acid, as well as nucleotide metabolites such as adenine and UMP in GBS HB31. Additionally, the NADH/NAD⁺ ratio increased while ATP levels decreased, indicating that the overall metabolic activity of GBS was suppressed. Transcriptomic analysis focused on changes in invasion-associated virulence genes. The results showed that the expression of pbsP, an invasion-associated virulence gene, was significantly reduced, while the expression of hylB and cfb showed downward trends that did not reach statistical significance. In contrast, the expression of cylE and the two-component system vicKR was upregulated. The upregulation of cylE may be related to baicalein-induced oxidative stress in HB31. Furthermore, HB31 suppressed Nrf2-HO-1 mRNA expression, whereas baicalein activated the Nrf2 signaling pathway and reduced HB31-induced IL-6 and NF-κBmRNA expression. These findings provide new insights for the development of anti-virulence therapeutic strategies targeting GBS. Full article

Bovine mastitis is a common inflammatory disease that can progress to mammary fibrosis, thereby impairing udder health, milk yield, and milk quality. This study investigated the protective effects of palmatine on lipopolysaccharide (LPS)-induced epithelial–mesenchymal transition (EMT) in bovine mammary epithelial cells and mammary fibrosis in mice, as well as the underlying mechanisms. In vitro, palmatine markedly reversed LPS-induced EMT by increasing E-cadherin expression and decreasing N-cadherin and α-SMA expression. In vivo, palmatine alleviated inflammatory cell infiltration and collagen deposition in mammary tissue and reduced the expression of TGF-β1, p-Smad2, p-Smad3, p-p65, TNF-α, IL-1β, and IL-6. These findings suggest that palmatine alleviates LPS-induced mammary fibrosis, possibly through inhibition of the NF-κB/TGF-β1/Smad signaling pathway, and may represent a potential therapeutic strategy for the prevention and treatment of mammary fibrosis. Full article