Antimicrobial Resistance of Extended-Spectrum Cephalosporins and Fluoroquinolones in Salmonella spp.: Mechanism of Resistance and Epidemiology

Abstract

Salmonella   is a pathogen responsible  for salmonellosis,  a world-wide  public health

concern. Most infections from this microbe are the results of ingestion of contaminated food. Treatment with drugs, such as cephalosporins or fluoroquinolones is recommended for infections when severe diarrhea is a symptom. Recently, however, there are several reports of Salmonella antimicrobial resistance to these two popular treatments. Cephalosporin resistance is usually due to the production of β-lactamases such as CTX-M,  TEM, OXA and SHV etc. The β-lactam ring

can be broken by those  β-lactamases leading to the inhibition of antibiotic activity. There are

several mechanisms of fluoroquinolones  resistance, including 1) mutation of DNA gyrase and topoisomerase IV; 2) production of enzymes for hydrolyzing drugs, such as aminoglycoside acetyltransferase (AAC(6’)-Ib-cr);  3) production of efflux pumps, OqxAB and QepA; and 4) production of proteins protecting DNA gyrase, such as Qnr. The purpose of this review was to focus on the current status of cephalosporin and fluoroquinolone resistance, including mechanism of resistance as well as epidemiology of the antimicrobial resistance.