Rev Esp Quimioter 2015:28(1):36-38

Salmonella enterica with nonclassical quinolone resistance phenotype in pediatric patients                                 



Introduction. Decreased susceptibility to fluoroquinolones in Salmonella spp. may lead to treatment failures. The use of ciprofloxacin for extraintestinal and serious intestinal Salmonella infections in children is controversial and therefore the clinical relevance of these strains is not significant. Consequently little is know about the quinolone resistance of strains Salmonella of our paediatric population. The objective of this study was to assess the incidence of nonclassical quinolone resistance phenotype in paediatric patients.
Material and methods. Two hundred and sixty eight Salmonella spp. from Hospital Infantil Universitario Niño Jesús of Madrid (2009-2013) were tested against nalidixic acid and ciprofloxacin by microdilution. Moreover, 146 strains (2011-2013) were tested against ciprofloxacin by E-test. Reduced ciprofloxacin susceptibility was defined as a MIC of 0.125-1 mg/L.
Results. Of 42 isolates with reduced ciprofloxacin susceptibility, four isolates showing nonclassical quinolone resistance phenotype. Three were confirmed as carrying of plasmid-mediated quinolone resistance-conferring genes qnr.
Conclusions. The percentage of strains with a genotype that confers a nonclassical quinolone resistance phenotype is low in our series. The identification of these isolates is difficult using conventional methods, but its ability of horizontal spread recommends an appropriate identification. Taking into account the low isolation rate of these strains in this study, evaluation of ciprofloxacin MIC on every nalidixic acid susceptible strain would not be cost effective. Alternatively, we propose to evaluate periodically any changing trend.

Rev Esp Quimioter 2015:28(1):36-38 [pdf]