Exploring the MALDI Biotyper for the Identification of Corynebacterium pseudotuberculosis biovar Ovis and Equi.

Biochemical, serological, and molecular methods have been developed for the laboratory diagnosis of diseases caused by C. pseudotuberculosis (CP), but the identification of the pathogen and biovars differentiation may be time-consuming, expensive, and confusing compared with other bacteria. This study aimed to evaluate MALDI Biotyper and Overall Genome Relatedness Index (OGRI) analysis to optimize the identification and differentiation of biovars of C. pseudotuberculosis. Out of 230 strains isolated from several hosts and countries, 202 (87.8%) were precisely classified using MALDI Biotyper and the BioNumerics platform. The classification accuracies for the Ovis and Equi biovars were 80 (88.75%) and 82 (92.68%), respectively. When analyzing a sampling of these strains by Average Nucleotide Identity based on BLAST and TETRA analyses using genomic sequence data, it was possible to differentiate 100% of the strains in Equi and Ovis. Our data show that MALDI Biotyper and OGRI analysis help identify C. pseudotuberculosis at the species and biovar levels.

3D sponges of chemically functionalized chitosan for potential environmental pollution remediation: biosorbents for anionic dye adsorption and 'antibiotic-free' antibacterial activity.

In this work, it was developed three-dimensional (3D) porous hydrogel sponges produced by the freeze-dried process using chitosan polymer functionalized by 11-mercaptoundecanoic acid (MUA). These chitosan-based sponges were used as cationic adsorbents for the removal of anionic methyl orange (MO) dye, simulating a model organic pollutant in aqueous medium. Moreover, these porous 3D constructs were also evaluated as 'antibiotic-free' antibacterial materials against gram-negative and gram-positive bacteria, Pseudomonas aeruginosa and Staphylococcus aureus, respectively, which were used as model pathogens possibly found in contaminated hospital discharges. These 3D hydrogels were comprehensively characterized through morphological methods such as scanning electron microscopy and X-ray micro-computed tomography techniques, combined with FTIR, Raman, and UV-visible spectroscopy analyses. Additionally, the surface area, the degree of swelling, and the adsorption profiles and kinetics of these scaffolds were systematically investigated. The chemically thiolated chitosan (CHI-MUA) hydrogels were successfully produced with a supramolecular polymeric network based on hydrogen bonds, disulfide bonds, and hydrophobic interactions that resulted in higher stability in aqueous medium than hydrogels of pristine chitosan. CHI-MUA exhibited sponge-like three-dimensional structures, with highly interconnected and hierarchical pore size distribution with high porosity and surface area. These architectural aspects of the 3D sponges favoured the high adsorption capacity for MO dye (∼388 mg.g-1) in water with removal efficiency greater than 90% for MO solutions (from 20 mg.L-1-1200 mg.L-1). The adsorption data followed a pseudo-second-order kinetic model and adsorption isotherm analysis and spectroscopy studies suggested a multilayer behaviour with coexistence of adsorbent-adsorbate and adsorbate-adsorbate interactions. Additionally, the in vitro evaluation of toxicity (MTT and LIVE-DEAD® assays) of 3D-sponges revealed a non-toxic response and preliminary suitability for bio-related applications. Importantly, the 3D-sponges composed of chitosan-thiolated derivative proved high antibacterial activity, specificity against P. aeruginosa (model hazardous pathogen), equivalent to conventional antibiotic drugs, while no lethality against S. aureus (reference commensal bacteria) was observed.

Molecular epidemiology of Corynebacterium pseudotuberculosis isolated from horses in California.

Corynebacterium pseudotuberculosis biovar Equi is an important pathogen of horses. It is increasing in frequency in the United States, and is responsible for various clinical forms of infection, including external abscesses, internal abscesses of the abdominal or thoracic cavities, and ulcerative lymphangitis. The host/pathogen factors dictating the form or severity of infection are currently unknown. Our recent investigations have shown that genotyping C. pseudotuberculosis isolates using enterobacterial repetitive intergenic consensus (ERIC)-PCR is useful for understanding the evolutionary genetics of the species as well for molecular epidemiology studies. The aims of the present study were to assess (i) the genetic diversity of C. pseudotuberculosis strains isolated from horses in California, United States and (ii) the epidemiologic relationships among isolates. One hundred and seven C. pseudotuberculosis biovar Equi isolates from ninety-five horses, and two C. pseudotuberculosis biovar Ovis strains, C. pseudotuberculosis ATCC 19410T type strain and C. pseudotuberculosis 1002 vaccine strain, were fingerprinted using the ERIC 1+2-PCR. C. pseudotuberculosis isolated from horses showed a high genetic diversity, clustering in twenty-seven genotypes with a diversity index of 0.91. Minimal spanning tree showed four major clonal complexes with a pattern of temporal clustering. Strains isolated from the same horse showed identical ERIC 1+2-PCR genotype, with the exception of two strains isolated from the same animal that showed distinct genotypes, suggesting a co-infection. We found no strong genetic signals related to clinical form (including internal versus external infections). However, temporal clustering of genotypes was observed.