Comparison of minimum inhibitory concentration values for fluoroquinolonesagainst Escherichia coli causing urinary tract infection in both hospitalized patients and outpatients

Objective: To determine the resistance among Escherichia coli isolates caus ing urinary tract infections in hospitalized patients and outpatients. Methods: This study was carried out in the Department of Microbiology, Doku z Eylul University, Medical Faculty Hospital, Inciralti, Ismir, Turkey, fro m February 1997 through to June 1998. A total of 300 Escherichia coli strai ns were isolated from urine specimens of I I I hospitalized and 189 elderly outpatients (more than 20 years of age). We determined the minimum inhibit ory Concentrations of the test drugs nalidixic acid, pefloxacin, ofloxacin, norfloxacin and ciprofloxacin by the microdilution method, recommended by the National Committee for Clinical Laboratory Standards. Results: Minimum inhibitory concentrations, and minimum inhibitory concentr ations,, values of strains tested against fluoroquinolones, pefloxacin and nalidixic acid were the same for strains isolated from hospitalized and out patients (0.125 mug/ml outpatients (0.03 mug/ml). Twenty-six (9%) of 300 Es cherichia coli strains were resistant to all drugs used. Twenty (77%) of th ese 26 strains were isolated from hospitalized patients. We found that the resistance to nalidixic acid is much higher than other fluoroquinolones. At the same time, the resistance in the strains that were isolated from hospi talized patients is again higher than outpatient strains (46%). Conclusion: Resistance among Escherichia coli isolates from patients to qui nolones used in the treatment of urinary tract infections was rare during t his period. Our study, like many other reports showed the increased resista nce to fluoroquinolones for clinical isolates. However the appearance of mu lti resistant clones and the elevated prevalence of quinolones resistance i n the hospital studied are warning signals for an increase in resistant str ains as seen in many other countries. Therefore, it is important for physic ians to use fluoroquinolones carefully so as to prevent, or delay, the emer gence of resistant strains.