OBJECTIVE: To assess time trends in the frequency of norfloxacin and ciprofloxacin resistance of bacteria isolated from urine culture. METHODS: Results of all urine cultures with a bacterial growth of at least 10(5) colony-forming units per milliter, performed at the Renal Service of the Federal University of Bahia, Brazil, from 1983 to 1994 were analyzed. The bacteria considered for this analysis were those most often isolated: Escherichia coli (n=668), Klebsiella spp. (n=286), Staphylococcus spp. (n=186), Proteus spp. (n=135) and Enterobacter spp. (n=129). RESULTS: The frequencies of norfloxacin resistance for the periods 1983-1986, 1987-1990 and 1991-1994 were 3.2%, 5.9% and 9.1%, respectively (p-value<0.05). The most pronounced increases in the frequencies of norfloxacin-resistance were observed for Klebsiella spp. and Enterobacter spp. The frequency of ciprofloxacin resistance was 7.4% in the period 1985-1989 and 16.5% in the period 1990-1994 (p-value<0.05). This time trend in ciprofloxacin resistance was more striking for Enterobacter spp. and Staphylococcus spp. CONCLUSION: The results show a gradual increase in the frequency of norfloxacin and ciprofloxacin resistance of the bacteria most commonly isolated from urine cultures. The influence of previous treatment with quinolones and characteristics of the infecting bacteria on these findings are important questions to to be addressed in future investigations.
Antimicrobial resistance; Quinolone; Urinary tract infection
