Characterization of genes associated with resistance to nalidixic acid and Ciprofloxacin reduced susceptibility of Salmonella spp. strains isolated in the State of São Paulo

Abstract

Salmonella spp are the most frequent causative agents of foodborne disease. Clinical manifestations of human infections with Salmonella spp. cause from mild to severe gastroenteritis intestinal and extra-intestinal infections such as bacteremia, sepsis and meningitis, including typhoid fever. Antimicrobial therapy is essential for immunocompromised patients, the elderly or children, or in severe cases or invasive caused by Salmonella, and ciprofloxacin (fluorquinolone) is recommended as the drug of first choice for treatment. The resistance to fluorquinolones is still rare in Salmonella spp. However, in recent decades the emergence and spread of resistance to nalidixic acid (quinolone first generation) associated with reduced susceptibility to ciprofloxacin among Salmonella serotypes, it has become of great interest public health, interfering directly in response to clinical treatment. The multidrug resistance in Salmonella has been increased due to the indiscriminate use of antimicrobial agents in the treatment and prophylaxis human and veterinary medicine. In this paper we will study 91 Salmonella strains exhibiting resistance to nalidixic acid and reduced susceptibility to ciprofloxacin, cases of human infections and non-human origin (mostly food), isolated in the state of São Paulo. The aim of this study is to characterize genetic mutations in regions determinants of resistance to quinolones (QRDR), detect and identify plasmid genes mediating acquired resistance to quinolones (PMQR), as well as verify the genetic diversity among the strains. For this techniques will be used phenotypic and genotypic typing as serotyping, antimicrobial susceptibility testing, polymerase chain reaction, sequencing and pulsed field electrophoresis. The results contribute to knowledge about the molecular mechanisms of resistance to fluorquinolones among Salmonella strains widespread in our region, warning of the indiscriminate use of fluorquinolones in human and veterinary medicine, to reduce the selection pressure and prevent the emergence of resistant clones. (AU)