Phenotypic and genotypic characterization of aminoglycoside resistance in Acinetobacter baumannii

Abstract

Acinetobacter baumannii is one of the main bacterial agents associated with healthcare infections, mainly in immunocompromised patients. This species present intrinsic and acquired antimicrobial resistance determinants, reducing the therapeutic option for the treatment of infections. Over the last decades, carbapenems were one of the main antimicrobial agents used for the treatment of Acinetobacter infections, however, emergence and dissemination of carbapenemase enzymes led to the utilization of another classes of antimicrobial agents, such as the aminoglycosides. Aminoglycosides act by binding to specific ribosomal subunits, inhibiting the protein synthesis. Nevertheless, production of aminoglycoside modifying enzymes (AMEs) can inactivate these antimicrobials, leading to resistance. Thus, the aim of this study is to evaluate the antimicrobial susceptibility to aminoglycosides and to detect the main aminoglycoside modifying enzymes genes in a collection of Acinetobacter baumannii. A total of 40 non-repetitive A. baumannii strains were recovered from bloodstream hospitalized patients, identified by Vitek II, and stored for this study. Susceptibility to amikacin, gentamicin and tobramycin will be assessed by E-test, and the minimal inhibitory values will be classified in susceptible, intermediate and resistance according to CLSI 2016. The aac(3)-Ia, aac(3)-IIa, aac(62)-Ih, aph(32)-VI, ant(2")-Ia, aph(32)-Ia, aac(62)-Ib genes will be detected by multiplexed polymerase chain reaction. Correlation between the susceptibility profiles and the PCR results will be conducted. (AU)