Molecular and phenotypic characterization of Staphylococcus spp. methicillin-resistant strains isolated from dogs, humans, and house dust

• Grant number: 23/11688-5
• Support Opportunities: Scholarships in Brazil - Master
• Effective date (Start): April 01, 2024
• Effective date (End): July 31, 2025
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Principal Investigator: Ilana Lopes Baratella da Cunha Camargo
• Grantee: Luciana Roberta Torini de Souza
• Host Institution: Instituto de Física de São Carlos (IFSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

Staphylococcus are gram-positive bacteria found on humans' and animals' skin and mucous membranes and are widely distributed in soil, water, and food. The Staphylococcus genus includes more than 80 species and subspecies, with Staphylococcus aureus and Staphylococcus epidermidis being the most well-known. Despite being part of the normal human microbiota, these microorganisms can cause diseases ranging from simple infections to severe and fatal infections. From a genetic standpoint, Staphylococcus spp. have a genome of around 3 megabases (Mb), containing genes encoding virulence factors and genes that confer antibiotic resistance. As they are present on the skin and mucous surfaces of humans and animals, staphylococci are in contact with a wide diversity of bacteria, leading to a high degree of genomic plasticity. Thus, genetic materials can be exchanged among Staphylococcus in an intra-species and inter-species exchange and inter-genus exchange, meaning between Staphylococcus and other gram-positive bacteria. This exchange confers different degrees of virulence and primarily resistance to antimicrobials. This study will investigate the diversity of methicillin-resistant Staphylococcus species and characterize isolates from human communities, dogs, and household dust regarding resistance and virulence. All methicillin-resistant isolates will be fully characterized phenotypically and genotypically, as their genomes will be sequenced using both Illumina and Nanopore technologies, resulting in a complete genome. This will also enable the study of plasmids and other mobile genetic elements in this bacterial genus to understand if there is evidence of genetic exchanges between species. Automating the Phoenix M50 equipment will determine identification and sensitivity profiles. Additionally, sensitivity to antimicrobials will be determined through disk diffusion and/or determination of minimum inhibitory concentration through broth microdilution. This way, it will be possible to identify which species are most prevalent in the community of São Carlos (SP), which show the highest antimicrobial resistance, and investigate the mechanisms leading to this phenotype.