Impact of intramammary inoculation of inactivated Lactobacillus rhamnosus and antibiotics on the milk microbiota of water buffalo with subclinical mastitis

Exploration of the Changes in Facial Microbiota of Maskne Patients and Healthy Controls Before and After Wearing Masks Using 16 S rRNA Analysis

Whether in the field of medical care, or in people's daily life and health protection, the importance of masks has been paid more and more attention. Acne, the most common complication after wearing masks, which is also called maskne, has been successfully introduced into the common language as a common topic of dermatologist consultations. This study aims to study the changes of microflora in maskne patients and healthy controls before and after wearing masks. In the summer of 2023, we collected a total of 50 samples from 15 maskne patients and 10 healthy controls before and after wearing surgical masks for a long time. 16 S ribosomal DNA sequencing and identification technology with V3-V4 variable region were adopted to explore the microbiome changes caused by mask wearing, analyze the changes in microbial diversity, and make interaction network. LDA effect size analysis was used to identify which bacteria showed significant changes in their relative abundance from phylum to genus. After wearing a mask, the microbiome of the maskne patients changed significantly more than that of the healthy controls, with both α diversity and β diversity lower than those of maskne patients before wearing masks and those of healthy controls after wearing masks. Co-occurrence network analysis showed that compared with other groups, the network of maskne patients after wearing masks for a long time had the lowest connectivity and complexity, but the highest clustering property, while the opposite was true for healthy controls. Many microbes that are potentially beneficial to the skin decreased significantly after wearing a mask. There was almost no difference in healthy controls before and after wearing a mask.

Exploring the Milk Microbiota of Healthy and Mastitic Nili Ravi Buffalo Using 16S rRNA Gene Base Metagenomic Analysis

The Nili Ravi, a buffalo breed from Pakistan, significantly contributes to the dairy industry. Mastitis is one of the major challenges affecting milk production in this breed. The objective of the current study was to identify the bacterial communities and diversity in healthy and mastitic milk of this breed. Milk samples (n = 14) were collected from Nili Ravi buffaloes with different udder health statuses, i.e., healthy (5), subclinical mastitis (4), and clinical mastitis (5). The DNAs were extracted, subjected to partial amplification of 16S rDNA (V3 and V4 regions), and sequenced using the Illumina platform. The results revealed variations in the bacterial communities in the milk of animals with different udder health statuses. Proteobacteria was the predominant phylum in the healthy group, while clinical and subclinical mastitis milk had a higher abundance of Firmicutes. Dominant bacterial genera in the healthy group were Streptococcus (11.60%), Herbaspirillum (7.65%), and Staphylococcus (4.70%), whereas the clinical mastitis group was dominated by Streptococcus (33.96%), Staphylococcus (7.87%), and Corynebacterium (2.68%), and the subclinical mastitis group was dominated by Bacillus (15.70%), Corynebacterium (6.70%), and Staphylococcus (6.58%). Assignment of operational taxonomic units at the species level resulted in most species being assigned to uncultured or unknown bacteria or remaining unassigned. Alpha diversity indices indicated lower microbial diversity in the clinical mastitis group, while beta diversity indices showed a scattered pattern of sample clustering in PCA plots among different groups. It is concluded that bacterial diversity in the milk of Nili Ravi buffaloes suffering from clinical mastitis is lower compared to healthy and subclinical mastitis cases. It is concluded that the variations in the microbiota of healthy and mastitic milk may be further investigated and exploited as signature microbes associated with the udder health status of Nili Ravi buffalo.

Immunomodulatory Effects of Probiotics: A Novel Preventive Approach for the Control of Bovine Mastitis

Bovine mastitis (BM) is one of the most common diseases of dairy cattle, causing economic and welfare problems in dairy farming worldwide. Because of the predominant bacterial etiology, the treatment of BM is mostly based on antibiotics. However, the antimicrobial resistance (AMR), treatment effectiveness, and the cost of mastitis at farm level are linked to limitations in the antibiotic therapy. These scenarios have prompted the quest for new preventive options, probiotics being one interesting alternative. This review article sought to provide an overview of the recent advances in the use of probiotics for the prevention and treatment of BM. The cellular and molecular interactions of beneficial microbes with mammary gland (MG) cells and the impact of these interactions in the immune responses to infections are revised. While most research has demonstrated that some probiotics strains can suppress mammary pathogens by competitive exclusion or the production of antimicrobial compounds, recent evidence suggest that other probiotic strains have a remarkable ability to modulate the response of MG to Toll-like receptor (TLR)-mediated inflammation. Immunomodulatory probiotics or immunobiotics can modulate the expression of negative regulators of TLR signaling in the MG epithelium, regulating the expression of pro-inflammatory cytokines and chemokines induced upon pathogen challenge. The scientific evidence revised here indicates that immunobiotics can have a beneficial role in MG immunobiology and therefore they can be used as a preventive strategy for the management of BM and AMR, the enhancement of animal and human health, and the improvement of dairy cow milk production.

Changes in the lipidome of water buffalo milk during intramammary infection by non-aureus Staphylococci

This study aimed to determine the lipidome of water buffalo milk with intramammary infection (IMI) by non-aureus staphylococci (NAS), also defined as coagulase-negative staphylococci, using an untargeted lipidomic approach. Non-aureus Staphylococci are the most frequently isolated pathogens from dairy water buffalo milk during mastitis. A total of 17 milk samples from quarters affected by NAS-IMI were collected, and the lipidome was determined by liquid chromatography-quadrupole time-of-flight mass spectrometry. The results were compared with the lipidome determined on samples collected from 16 healthy quarters. The study identified 1934 different lipids, which were classified into 15 classes. The abundance of 72 lipids changed in NAS-IMI milk compared to healthy quarters. Significant changes occurred primarily in the class of free fatty acids. The results of this study provided first-time insight into the lipidome of dairy water buffalo milk. Moreover, the present findings provide evidence that NAS-IMI induces changes in water buffalo milk's lipidome.

In vitro anti-tuberculosis effect of probiotic Lacticaseibacillus rhamnosus PMC203 isolated from vaginal microbiota

Mycobacterium tuberculosis (M. tb), the etiological agent of tuberculosis (TB), poses a severe challenge for public health and remains the number one cause of death as a single infectious agent. There are 10 million active cases of TB per year with 1.5 million deaths, and 2-3 billion people are estimated to harbor latent M. tb infection. Moreover, the emergence of multi-drug-resistant (MDR), extremely-drug-resistant (XDR), and the recent totally drug-resistant (TDR) M. tb is becoming a global issue that has fueled the need to find new drugs different from existing regimens. In these circumstances, probiotics can be a potential choice, so we focused on developing them as an anti-tuberculosis drug candidate. Here, we report the anti-tubercular activities of Lacticaseibacillus rhamnosus PMC203 isolated from the vaginal microbiota of healthy women. PMC203 exhibited a promising intracellular killing effect against both drug-sensitive and resistant M. tb infected murine macrophage cell line RAW 264.7 without showing any cytotoxicity. Additionally, it also inhibited the growth of M. tb under broth culture medium. PMC203 did not cause weight change or specific clinical symptoms in a 2-week repeated oral administration toxicity test in a guinea pig model. Here, we also found that PMC203 induces autophagy in a dose dependent manner by increasing the signal of well-known autophagy gene markers, suggesting a possible intracellular killing mechanism.

A potential treatment approach for subclinical mastitis in dairy cows: auriculotherapy of the auricular branch of the vagus nerve

This research aims to test the hypothesis that neural therapy (NT) on the auricular branch of the vagus nerve (ABVN) in dairy cows diagnosed with subclinical mastitis (SCM) results in a reduction of the somatic cell count. Therapeutic options for SCM are mostly based on use of antibiotics and often lead to unsatisfactory results. An alternative therapy targeting the anti-inflammatory properties of the vagus nerve showing good efficacy, economic viability and without major side effects would be of considerable interest. Auriculotherapy (AT) was performed using three repeated infiltrations of 8.0 mg (0.4 ml) procaine hydrochloride (2%) at the location of the ear tag associated with the auricular acupuncture point (AAP) of the udder. Some 85 clinically healthy cows from nine dairy farms were sampled for evaluation of quarter somatic cell count (QSCC) on four days (d0, d2, d4 and d6). Quarters with a QSCC > 100 000 cells/ml on d0 were included in the analysis. Over the study period, a total of 784 quarters were analysed, 385 control (CON) quarters from 40 cows and 399 treated (TRE) quarters from 45 cows. Results showed that AT of the ABNV resulted in a significant reduction of the QSCC after three treatments. The effect was independent of bacteriological culture results of the quarter milk samples. The bacteriological cure rate, however, was not influenced by AT. To our knowledge this is the first report of AT reducing QSCC in dairy cows with SCM. Before AT can be regarded as an alternative therapeutic approach, further research should focus on possible long-term effects of AT on the reduction of SCC, any bacterial elimination and the neural pathways of AT in dairy cows with SCM.

Bacillus velezensis AP183 Inhibits Staphylococcus aureus Biofilm Formation and Proliferation in Murine and Bovine Disease Models

The increasing frequency of S. aureus antimicrobial resistance has spurred interest in identifying alternative therapeutants. We investigated the S. aureus-inhibitory capacity of B. velezensis strains in mouse and bovine models. Among multiple B. velezensis strains that inhibited S. aureus growth in vitro, B. velezensis AP183 provided the most potent inhibition of S. aureus proliferation and bioluminescence in a mouse cutaneous wound (P = 0.02). Histology revealed abundant Gram-positive cocci in control wounds that were reduced in B. velezensis AP183-treated tissues. Experiments were then conducted to evaluate the ability of B. velezensis AP183 to prevent S. aureus biofilm formation on a tracheostomy tube substrate. B. velezensis AP183 could form a biofilm on a tracheostomy tube inner cannula substrate, and that this biofilm was antagonistic to S. aureus colonization. B. velezensis AP183 was also observed to inhibit the growth of S. aureus isolates originated from bovine mastitis cases. To evaluate the inflammatory response of mammary tissue to intramammary inoculation with B. velezensis AP183, we used high dose and low dose inocula in dairy cows. At the high dose, a significant increase in somatic cell count (SCC) and clinical mastitis was observed at all post-inoculation time points (P < 0.01), which resolved quickly compared to S. aureus-induced mastitis; in contrast, the lower dose of B. velezensis AP183 resulted in a slight increase of SCC and no clinical mastitis. In a subsequent experiment, all mammary quarters in four cows were induced to have grade 1 clinical mastitis by intramammary inoculation of a S. aureus mastitis isolate; following mastitis induction, eight quarters were treated with B. velezensis AP183 and milk samples were collected from pretreatment and post-treatment samples for 9 days. In groups treated with B. velezensis AP183, SCC and abundance of S. aureus decreased with significant reductions in S. aureus after 3 days post-inoculation with AP183 (P = 0.04). A milk microbiome analysis revealed significant reductions in S. aureus relative abundance in the AP183-treated group by 8 days post-inoculation (P = 0.02). These data indicate that B. velezensis AP183 can inhibit S. aureus biofilm formation and its proliferation in murine and bovine disease models.

Heat inactivation partially preserved barrier and immunomodulatory effects of Lactobacillus gasseri LA806 in an in vitro model of bovine mastitis

Probiotics could help combat infections and reduce antibiotic use. As use of live bacteria is limited in some cases by safety or regulatory concerns, the potential of inactivated bacteria is worth investigating. We evaluated the potential of live and heat-inactivated Lactobacillus gasseri LA806 to counteract Staphylococcus aureus and Escherichia coli infection cycles in an in vitro model of bovine mastitis. We assessed the ability of live and inactivated LA806 to impair pathogen colonisation of bovine mammary epithelial cells (bMECs) and to modulate cytokine expression by pathogen-stimulated bMECs. Live LA806 induced a five-fold decrease in S. aureus adhesion and internalisation (while not affecting E. coli colonisation) and decreased pro-inflammatory cytokine expression by S. aureus-stimulated bMECs (without interfering with the immune response to E. coli). The ability of inactivated LA806 ability to diminish S. aureus colonisation was two-fold lower than that of the live strain, but its anti-inflammatory properties were barely impacted. Even though LA806 effects were impaired after inactivation, both live and inactivated LA806 have barrier and immunomodulatory properties that could be useful to counteract S. aureus colonisation in the bovine mammary gland. As S. aureus is involved in various types of infection, LA806 potential would worth exploring in other contexts.

Impact of yeast and lactic acid bacteria on mastitis and milk microbiota composition of dairy cows

This experiment was conducted to evaluate the impact of yeast and lactic acid bacteria (LAB) on mastitis and milk microbiota composition of dairy cows. Thirty lactating Holstein cows with similar parity, days in milk were randomly assigned to five treatments, including: (1) Health cows with milk SCC < 500,000 cells/mL, no clinical signs of mastitis were found, fed basal total mixed ration (TMR) without supplementation (H); (2) Mastitis cows with milk SCC > 500,000 cells/mL, fed basal TMR without supplementation (M); (3) Mastitis cows fed basal TMR supplemented with 8 g day^-1 yeast (M + Y); (4) Mastitis cows fed basal TMR supplemented with 8 g day^-1 LAB (M + L); (5) Mastitis cows (milk SCC > 500,000 cells/mL) fed basal TMR supplemented with 4 g day^-1 yeast and 4 g day^-1 LAB (M + Y + L). Blood and milk sample were collected at day 0, day 20 and day 40. The results showed efficacy of probiotic: On day 20 and day 40, milk SCC in H, M + Y, M + L, M + Y + L was significantly lower than that of M (P < 0.05). Milk concentration of TNF-α, IL-6 and IL-1β in M + Y + L were significantly reduced compared with that of M on day 40 (P < 0.05). Milk Myeloperoxidase (MPO) and N-Acetyl-β-D-Glucosaminidase (NAG) activity of M + Y, M + L, M + L + Y were lower than that of M on day 40 (P < 0.05). At genus level, Staphylococcus, Chryseobacterium and Lactococcus were dominant. Supplementation of LAB decreased abundance of Enterococcus and Streptococcus, identified as mastitis-causing pathogen. The results suggested the potential of LAB to prevent mastitis by relieving mammary gland inflammation and regulating milk microorganisms.

Short communication: Milk microbiota profiling on water buffalo with full-length 16S rRNA using nanopore sequencing

The identification of milk microbial communities in ruminants is relevant for understanding the association between milk microbiota and health status. The most common approach for studying the microbiota is amplifying and sequencing specific hypervariable regions of the 16S rRNA gene using massive sequencing techniques. However, the taxonomic resolution is limited to family and, in some cases, genus level. We aimed to improve taxonomic classification of the water buffalo milk microbiota by amplifying and sequencing the full-length 16S rRNA gene (1,500 bp) using Nanopore sequencing (single-molecule sequencing). When comparing with short-read results, we improved the taxonomic classification, reaching species level. We identified the main microbial agents of subclinical mastitis at the species level that were in accordance with the microbiological culture results. These results confirm the potential of single-molecule sequencing for in-depth analysis of microbial populations in dairy animals.