Regulatory mechanisms of the resistance to beta-lactam antibiotics on Chromobacterium violaceum

• Grant number: 18/02465-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2018
• End date: May 31, 2019
• Field of knowledge: Biological Sciences - Genetics - Molecular Genetics and Genetics of Microorganisms
• Principal Investigator: José Freire da Silva Neto
• Grantee: Carlos Eduardo Milani Neme
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

The emergence of antibiotic resistant bacterial pathogens is a serious public health problem. Resistance to beta-lactam antibiotics mediated by beta-lactamase enzymes spreads quickly among Gram-negative pathogenic bacteria. In this work, we intend to investigate the reasons and the regulatory mechanisms for the high intrinsic resistance to beta-lactam antibiotics observed in the Gram-negative bacterium Chromobacterium violaceum, a human opportunistic pathogen found ubiquitously in the environment. Two potential beta-lactamase enzymes from classes B and C codified at the C. violaceum chromosome have been identified with in silico analysis, besides genes involved in perception, signal transduction and regulation on the peptidoglycan biosynthesis pathway. In order to study them, we will obtain mutant strains of C. violaceum deleted from each gene encoding these enzymes, as well as mutant strains lacking regulatory genes. The susceptibility of these mutant strains will be evaluated for several beta-lactam antibiotics by disk diffusion assays (antibiogram) and by minimum inhibitory concentration (MIC).These assays, together with enzymatic and gene expression analysis, using different groups of beta-lactams or in the regulatory mutants must reveal the inducibility and specificity of the C. violaceum beta-lactamase enzymes. Altogether, the results obtained in this project shall contribute to understand how occur regulation of the high intrinsic resistance of C. violaceum to an important class of antibiotics, and could possibly bring assistance to a more efficient antibiotic therapy when treating infections caused by this bacterium.