Genotyping and molecular analysis of resistance determining to B-lactam antibiotic in Acinetobacter baumannii

Abstract

Acinetobacter baumannii is an important opportunistic pathogen responsible for a wide range of nosocomial infections. Additionally, some of these bacteria have resistance mechanisms to several classes of antimicrobial agents, including B-lactams. The B-lactam antibiotics are the main component of the current scenario used for microbial infections treatment and represent over 65% of the global antibiotic market. However, the resistance to this class of antibiotics has increased worldwide among A. baumannii isolates. This study aims to characterize the genetic diversity and to determine the molecular mechanisms of resistance to B-lactam antibiotics present in a population of A. baumannii. It will be studied 60 A. baumannii isolates collected from both hospitalized patients in intensive care units (ICUs) and outpatients in a hospital in the city of Ribeirao Preto/SP. Molecular characterization of resistance mechanisms will be performed by polymerase chain reaction (PCR) by the search of several B-lactamase-encoding genes, as well as by the search of integrons and of the ISAbaI insertion sequence. The typing of gene cassettes will be performed by restriction fragment length polymorphism (RFLP) analysis followed by sequencing. The genotyping of the isolates will be performed by pulsed-field gel electrophoresis (PFGE). The results to be obtained will help for a better understanding of the genetic diversity and of the mechanisms responsible for the resistance to B-lactam antibiotics in A. baumannii, a currently relevant pathogen.