Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of paratuberculosis, a contagious infectious disease that affects domestic and wild ruminants causing chronic inflammation of the intestine. MAP has proven to be very resistant to both physical and chemical processes, making it difficult to control this pathogen. Based on the recognized antimicrobial properties of copper, the objective of this study was to evaluate the effectiveness of copper ions to reduce MAP numbers and/or MAP viability in a fluid matrix. Besides, methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia coli were used as controls of the effectiveness of copper ions. MAP-spiked PBS was subjected to copper ions treatment at 24 V for 5 min and the PBS suspensions were sampled before and after treatment. MAP viability and quantification were determined using three complementary techniques: a phage amplification assay, MGIT culture and qPCR. Moderate numbers (103 CFU ml−1) of the two control bacteria were completely eliminated by treatment with copper ions. For MAP, copper ions treatment reduced both the viability and numbers of this pathogen. Phage assay information quickly showed that copper ions (24 V for 5 min) resulted in a significant reduction in viable MAP. MGIT culture results over time showed statistically significant differences in time-to-detection (TTD) values between PRE and POST treatment. MAP genome equivalent estimates for PBS suspensions indicated that MAP numbers were lower in samples POST-treatment with copper ions than PRE-treatment. The use of copper ions resulted in a significant reduction of MAP in a liquid matrix, although some MAP survival on some occasions was observed.

As part of a larger study on Epsilonproteobacteria carried by wild birds in the city of Valdivia (southern Chile), two curved rod-shaped Gram-stain-negative strains (A82^T and WB-40) were recovered from faecal samples and subjected to a taxonomic study. Results of a genus-specific PCR showed that these isolates belonged to the genus Helicobacter . Further identification by 16S rRNA and hsp60 (60 kDa heat-shock protein) gene sequence analysis revealed that they formed a separate phylogenetic clade, different from other known Helicobacter species with ‘Helicobacter burdigaliensis’ CNRCH 2005/566H^T and Helicobacter valdiviensis WBE14^T being the most closely related species. This was confirmed by core-genome phylogeny as well as digital DNA–DNA hybridization and average nucleotide identity analyses between the genomes of strains A82^T and WB-40 and all other Helicobacter species. The draft genome sequences of A82^T and WB-40, obtained by Illumina NextSeq 2000 sequencing, consisted of 1.6 Mb with a G+C content of 31.9–32.0 mol%. The results obtained from the phylogenetic and genomic characterization, together with their different morphological and biochemical features, revealed that these two strains represent a novel species, for which we propose the name Helicobacter ibis sp. nov. with A82^T (=LMG 32718^T=CCCT 22.04^T) as the type strain.

Ketosis is a common metabolic disease affecting dairy cows during early lactation. β-Hydroxybutyrate, the predominant ketone body in the bloodstream of ketotic cows, has been linked to neutrophil dysfunction and a higher incidence of mastitis. Neutrophils, the first line of cellular defense against bacteria, rely heavily on carbohydrate metabolism. In this study, we investigated the effect of high BHB concentrations on glycolysis and on the functional response of bovine neutrophils to Staphylococcus aureus-a leading cause of mastitis worldwide-and to Pam₃CSK₄, a synthetic agonist of toll-like receptor 2/1 (TLR2/1), which is critical for S. aureus recognition by immune cells. At both 2.5- and 5.0-mM concentrations, BHB reduced basal glycolysis and restricted the glycolytic capacity of neutrophils following Pam₃CSK₄ stimulation. By pharmacological inhibition, we confirmed that bovine neutrophils depend on both glycolysis and glycogenolysis to mount effective responses to S. aureus and Pam₃CSK₄. Interestingly, both 2.5- and 5.0-mM BHB similarly impaired neutrophil responses against S. aureus and Pam₃CSK₄, including respiratory burst, neutrophil extracellular traps formation, matrix metallopeptidase 9 release, phagocytosis, and chemotaxis. Our findings suggest that BHB-mediated glycolytic restriction may constitute a central mechanism contributing to neutrophil dysfunction during ketosis, thereby increasing the susceptibility of dairy cows to mastitis in early lactation.

Background: Bovine mastitis caused by Prototheca spp. is the most significant animal disease of algal origin, with an increasing number of cases reported worldwide. Currently, there is no effective treatment, so control requires the culling of infected animals. In Chile, information is limited, and a discrepancy remains in the literature regarding the Prototheca species involved in bovine mastitis. Methods: This study aimed to molecularly type and phenotypically characterize Prototheca isolates associated with bovine mastitis in Chile. Sixty-six Prototheca isolates obtained from individual bovine mastitis milk samples and bulk tank milk samples were analyzed through cytochrome b gene (cytb) sequencing, Random Amplified Polymorphic DNA–Polymerase Chain Reaction (RAPD-PCR) analysis, and phenotypic evaluation (morphology, antimicrobial susceptibility, and biofilm formation). Results: Sixty-five isolates were identified as P. bovis and one as P. ciferrii, marking the first report of the latter in bovine mastitis in Chile. RAPD analysis revealed a high genetic diversity in P. bovis. All strains exhibited resistance to the antibiotics tested from the Fluoroquinolone, β-lactam, and sulfonamide groups; however, 100% of the strains showed susceptibility to aminoglycosides, with gentamicin standing out as a potential therapeutic option. Most P. bovis strains formed weak (81.5%, 53/65) or moderate (15.4%, 10/65) biofilms, which could favor the persistence of infection. Conclusions: These findings provide novel insights into the molecular and phenotypic characteristics of Prototheca spp. in Chile, highlighting the predominance of P. bovis, the emergence of P. ciferri, and the implications for antimicrobial management and disease control.

We report the draft genome sequences of Bartonella sp. nov., strains EBT8 and P12B, isolated from a rodent and a rodent flea in Laguna Verde, Chile. The genome assemblies showed values below the cutoffs for species definition (ANI values ≤ 95% and dDDH values ≤ 70%) against other Bartonella species, indicating that the strains represent a putative novel species of the genus Bartonella .