Enteric fever caused by Salmonella isolates with decreased susceptibility to ciprofloxacin.

Abstract

With emerging drug resistance, ciprofloxacin became the frontline antibiotic against Salmonella strains causing enteric fevers worldwide. However, strains with decreased susceptibility to flouroquinolones have recently emerged as a problem in our region. Such strains are not detected by the routine disc diffusion method unless a nalidixic acid disc is also used. They are, however, important clinically since they show poor clinical responses and have higher faecal carriage rates following treatment with fluoroquinolones in usual doses. We report the first two cases of such strains in Sri Lanka, both acquired locally. We recommend the routine use of a nalidixic acid disc in sensitivity testing of Salmonella species, causing enteric fever in laboratories not determining minimum inhibitory concentrations (MICs) for fluoroquinolones in order to detect such strains, so that appropriate clinical decisions regarding antibiotic therapy can be made.