Impact of polymorphisms in blaZ, blaR1 and blaI genes and their relationship with ß-lactam resistance in S. aureus strains isolated from bovine mastitis.

There is not a consensus between the presence of the genotypic resistance marker gene and the phenotypic resistance to ß-lactams in Staphylococcus aureus, which means, positive S. aureus blaZ isolates demonstrating sensitivity to ß-lactams. The present study aimed to characterize the blaZ, blaR1 and blaI genes, identify and evaluate single nucleotide polymorphisms (SNPs) and their relationship with ß-lactam resistance in samples of Staphylococcus aureus obtained from cases of bovine mastitis. Five isolates (two resistant and three sensitive to oxacillin) of Staphylococcus aureus with detected production of beta-lactamase, previously evaluated as containing the blaZ gene and negative for the mecA and mecC genes, had the bla operon completely sequenced. Impacts on the protein sequence due to the detected polymorphisms were evaluated by modeling the proteins encoded by the blaZ, blaR1 and blaI genes using a three-dimensional model structure obtained from the Protein Data Bank (PDB) database. Fifteen SNPs were detected in the blaZ gene, 30 in the blaR1 gene and three in the blaI gene. These SNPs caused alterations in amino acid sites. Deleterious mutations were detected in the blaZ gene (E146G, P218S, Y221C) and the blaR1 gene (K481E). Molecular docking analysis revealed that polymorphisms in the blaZ gene may explain the phenotypic sensitivity in isolates that contain the resistance marker gene. Although sensitive and resistant isolates encode beta-lactamase, these proteins are functionally altered due to a change in the binding site with the antibiotic.

Molecular screening for the mutation associated with canine degenerative myelopathy (SOD1:c.118G > A) in German Shepherd dogs in Brazil.

Canine Degenerative Myelopathy is a late onset recessive autosomal disease characterized by a progressive ascending degeneration of the spinal cord. Two causal mutations are associated with this disease: a transition (c.118G>A) in exon 2 of the SOD1 that was described in several breeds and a transversion (c.52A>T) in exon 1 of the same gene described in Bernese Mountain dogs. The aim of this study was to understand the impact of the SOD1:c.118G > A mutation by genotyping a population of German Shepherd dogs in Brazil. A PCR-RFLP approach was used to genotype 97 healthy individuals belonging from the Northeast (Bahia and Pernambuco states) and South (Santa Catarina state) regions of Brazil. A total of 95 individuals were successfully genotyped resulting in an observed genotype frequency (with 95% confidence interval) of: 0.758 (0.672-0.844), 0.242 (0.156-0.328) and 0.000 (0.000-0.000) for "GG", "AG" and "AA" genotypes, respectively. To our knowledge, this is the first attempt to describe the presence of the "A" allele associated with CDM (SOD1:c.118G > A) in German Shepherd dogs in Brazil and, as such, these results contribute toward important epidemiological data in this country and to the knowledge of the distribution of the aforementioned mutation worldwide.

Neospora caninum DNA in feces of crab-eating fox (Cerdocyon thous - Linnaeus, 1776) from northeastern Brazil.

Neospora caninum is an obligate intracellular tissue cyst-forming coccidian parasite and it was first described in dogs. Despite the relevance of wild canids in the transmission chain of N. caninum, there are few studies in Brazil. The aim of the present study was to detect N. caninum DNA in feces of free-range and captive crab-eating fox (Cerdocyon thous) from different states of northeastern Brazil. Fecal samples of eighteen crab-eating foxes (fifteen individually and three pools) were collected in sterile containers and were kept cool at -20 °C until further processing. All fecal samples were subjected to DNA extraction. A nested PCR targeting the ITS-1 gene was performed for N. caninum. All the positive bands were extracted from the gel and purified. Forward and reverse strands were sequenced and the nucleotide sequences obtained were compared with N. caninum sequences deposited in Genbank. The alignment was edited and phylogenetic reconstruction was based on the ITS1 gene sequences. Thirteen stool samples were PCR-positive for N. caninum DNA. Nine out of thirteen positive samples showed similarity between 99%-100% for N. caninum in relation to the sequence U25044.1 stored at GenBank. The crab-eating fox could have an important role in the sylvatic cycle of Neospora caninum in Brazil. Experimental infections studies involving these wild canids may confirm if the crab-eating foxes are definitive hosts of N. caninum.