Investigation of the change of fluoroquinolone resistance over years in urinary Escherichia coli isolates

Aim: In the face of rapidly increasing antibiotic resistance among urinary Escherichia coli (E.coli) isolates, it is important to follow the own resistance rates off all centers. This study aimed to investigate the resistance rates of urinary E.coli isolates against fluoroquinolones, the changes in rates over the last 6 years, and correlation with resistance rates to other antibiotics in our hospital. Material and Methods: Antibiotic susceptibilities of urinary E.coli isolates between January 2003 and December 2008 in the Clinical Microbiology Laboratory of Dr. Lütfi Kırdar Kartal Training and Research Hospital were evaluated retrospectively. The first isolate from each patient was taken into the study. Results: Of 5543 isolates, 27% were resistant to ciprofloxacin, 26.5 % to ofloxacin, 21.4% to gentamicin, 15.4 % to amikacin and 11.9 % produced extended spectrum beta-lactamase (ESBL). The resistance rates of ciprofloxacin and ofloxacin were 22.1% and 21.6% in 2003 and 34.3% and 35.5% in 2007, respectively (for both, p<0.001). ESBL rate was 4.3% in 2003 and 19% in 2008 (p<0.001). Of the isolates resistant to ofloxacin and ciprofloxacin, 31% and 32%, respectively, produced ESBL. There were positive correlations between fluoroquinolone resistance to other antibiotics. The resistance rates of the outpatient clinics were significantly lower than the rates of the inpatient clinics (p<0.001). Discussion: The resistance rate to quinolone group antibiotics in E.coli strains isolated in various centers in our country is up to 35%, and resistance rates were generally found to be similar among quinolones. In our study, resistance to ofloxacin was found at a rate of 26.5% and ciprofloxacin resistance at a rate of 27% for E.coli strains, and no significant difference was found between them (p<0.05). When infections caused by bacteria with and without ESBL growth are compared in terms of mortality, morbidity and health costs, excluding the patient group in which carbapenems are used as the first treatment, in infections with ESBL-producing isolates, it has been shown that mortality is higher, length of hospital stay is longer and health costs are higher. The mortality rate in infections developed by ESBL-producing bacteria, especially in intensive care patients, varies between 30-50%.