[Evolution of microbial resistance to fluoroquinolones at a tertiary hospital].

Within the setting of a reference tertiary hospital such as Hospital La Fe, a retrospective study of major germs responsible for urinary infections and their susceptibility to fluoroquinolones was conducted between 1990-1998 in an attempt to quantify the increased resistance found in both in- and out-patients. The rationale for the study was the clinical evidence of resistance to those antimicrobials. E. coli continues to be the most frequently isolated micro-organism in all types of urinary infections in both intra-hospital (50%) and extra-hospital infections (63%), followed by E. faecalis, P. mirabilis, and Klebsiella. When ward patients are compared to patients in Intensive Care Units (ICUs) a number of differences become apparent as regard to the isolated micro-organisms. Current resistance to fluoroquinolones is about 23% for E. coli, 28% for E. faecalis, 6.5% for P. mirabilis, 5% for Klebsiella spp, 15% for Pseudomonas aeruginosa and 9% for Enterobacter spp. When these results are compared to those seen at the beginning of the '90s a highly significant increase is noted for E. coli (from 3 to 23%), E. faecalis (from 4.5 to 28%) and Pseudomonas aeruginosa (from 4 to 15%) with a much lower increase for the remaining micro-organisms. The reasons behind such an increase are numerous, the major one being the massive use of quinolones both in humans and animals, with variations based on age and geographic region. Generalisation of this major increase would lead to future use of fluoroquinolones based on susceptibility in culture, particularly in serious urinary infections.