Comparative genomic analysis of ovine and other host associated isolates of Staphylococcus aureus exhibit the important role of mobile genetic elements and virulence factors in host adaptation.

Staphylococcus aureus is the main etiological agent of mastitis in small ruminants worldwide. This disease has a difficult cure and possible relapse, leading to significant economic losses in production, milk quality and livestock. This study performed comparative genomic analyses between 73 S. aureus genomes from different hosts (human, bovine, pig and others). This work isolated and sequenced 12 of these genomes from ovine. This study contributes to the knowledge of genomic specialization and the role of specific genes in establishing infection in ovine mastitis-associated S. aureus. The genomes of S. aureus isolated from sheep maintained a higher representation when grouped with clonal complexes 130 and 133. The genomes showed high genetic similarity, the species pan-genome consisting of 4200 genes (central = 2008, accessory = 1559 and unique = 634). Among these, 277 unique genes were related to the genomes isolated from sheep, with 39.6 % as hypothetical proteins, 6.4 % as phages, 6.4 % as toxins, 2.9 % as transporters, and 44.7 % as related to other proteins. Furthermore, at the pathogen level, they showed 80 genes associated with virulence factors and 19 with antibiotic resistance shared in almost all isolates. Although S. aureus isolated from ovine showed susceptibility to antimicrobials in vitro, ten genes were predicted to be associated with antibiotic inactivation and efflux pump, suggesting resistance to gentamicin and penicillin. This work may contribute to identifying genes acquired by horizontal transfer and their role in host adaptation, virulence, bacterial resistance, and characterization of strains affecting ovine.

First report and whole-genome sequencing of Pseudochrobactrum saccharolyticum in Latin America.

The Brucellaceae family comprises microorganisms similar both phenotypically and genotypically, making it difficult to identify the etiological agent of these infections. This study reports the first isolation, identification, and characterization of Pseudochrobactrum saccharolyticum (strain 115) from Latin America. Strain 115 was isolated in 2007 from a bovine in Brazil and was initially classified as Brucella spp. by classical microbiological tests and bcsp31 PCR. The antimicrobial susceptibility of strain 115 was tested against drugs used to treat human brucellosis by minimal inhibitory concentration test. Subsequently, the whole genome of the strain was sequenced, assembled, and characterized. Phylogenetic trees built from 16S rRNA and recA gene sequences enabled the classification of strain 115 as Pseudochrobactrum spp. Phylogenomic analysis using Single Nucleotide Polymorphisms and Average Nucleotide Identity allowed the classification of the strain as P. saccharolyticum. Additionally, a Tetra Correlation Search identified one related genome from the same species, which was compared with strain 115 by analyzing genomic islands. This is the first identification and whole-genome sequence of P. saccharolyticum in Latin America and highlights a challenge in the diagnosis of bovine brucellosis, which could be solved by including the sequencing of 16S rRNA and recA genes in routine diagnostics.

Atypical Multibacterial Granulomatous Myositis in a Horse: First Report in Italy.

Infectious causes of myositis are reported relatively uncommonly in horses. Among them, bacterial causes include Streptococcus equi subsp. zooepidemicus, Actinobacillus equuli, Fusobacterium spp. Staphylococcus spp, and Corynebacterium pseudotuberculosis. Infection can be spread to muscles via haematogenous or extension from skin lesions. Parasitic myositis has also been documented. In this report, a 12 year-old Italian Quarter Horse mare presented with diffuse subcutaneous nodules and masses ranging from 2 × 3 to 5 × 20 cm in size, and adherent to subcutis and muscles that were first macroscopically and cytologically diagnosed as pyogranulomas. Subsequently, histological, molecular, bacteriological, and biochemical investigations were performed. All the data obtained allowed to diagnose a severe and diffuse multibacterial granulomatous myositis caused by Corynebacterium pseudotuberculosis and Corynebacterium amycolatum. Following the therapy and an initial disappearance of most of the lesions together with a general improvement of the mare, the clinical condition deteriorated, and new nodules appeared. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) and PCR techniques revealed the presence of bacteria as Glutamicibacter creatinolyticus and Dietzia spp. To the authors' knowledge, this case report represents the first description of multibacterial granulomatous myositis due to Corynebacterium pseudotuberculosis, Corynebacterium amycolatum, Glutamicibacter creatinolyticus, and Dietzia spp. in a horse reared in Italy.