[Evolution of resistance to quinolonesin Salmonella enterica in our environment]

Salmonella enterica is mainly associated with acute gastroenteritis; however, it is also associated with other more severe disease processes, for which quinolones are the treatment of choice. We retrospectively studied the evolution of resistance to nalidixic acid and ciprofloxacin of all the clinical isolates of S. enterica from 1992 to 1998 in our hospital environment. A total of 848 strains from feces, blood and other locations were studied. We detected an increase in the resistance to nalidixic acid from 12% in 1992 to 21.3% in 1998, especially in the Enteritidis and Hadar serotypes. We did not detect resistance to ciprofloxacin, but there was in increase in the MIC in the nalidixic acid-resistant strains. Although this is interpreted as sensitive according the the NCCLS criteria, if we apply the cutoff points established by MENSURA, 89.46% of the strains do not fit into this category (S <0.12 mg/l). This puts into question the utility of quinolones in the long-term treatment of severe disease processes produced by this type of strain.