Evaluation of Various Risk Factors for the Emergence of Resistance to Fluoroquinolones

The continuing emergence of resistance to fluoroquinolones together with the widespread use is of great concern. To identify the risk factors associated with fluoroquinolone resistant gram-negative bacilli (GNB) infection, a prospective, unmatched, case-control study during a 16-month-period from November 2002 to March 2004 was conducted. A hundred and thirty patients, from whom fluoroquinolone resistant GNB were isolated, were compared with 50 control patients, from whom fluoroquinolone susceptible GNB were isolated. Potential risk factors were obtained through review of inpatient medical records and evaluated by statistical methods. Risk factors that were significantly associated with fluoroquinolone resistant GNB infection included presence of advanced age (p= 0.009), male sex (p< 0.001; OR 3.927; 95% CI 1.970-7.829), underlying malignancy (p= 0.026; OR 2.809; 95% CI 1.102-7.157), lower urinary system pathology (p= 0.009; OR 8.909; 95% CI 1.163-68.269), prior surgical operation (p= 0.012; OR 2.406; 95% CI 1.200-4.828), prior use of fluoroquinolones (p< 0.001; OR 7.563; 95% CI 3.015-18.970), attendence to urology clinics (p= 0.003; OR 3.039; 95% CI 1.432-6.451), urinary catheterization (p= 0.004; OR 2.649; 95% CI 1.356-5.174), extendedspectrum beta-lactamase (ESBL) producing Escherichia coli or Klebsiella spp. as infecting pathogen (p= 0.001; OR 6.000; 95% CI 1.756-20.501) and the resistance to other antibiotics than carbapenems (p< 0.05). In multivariate analysis, male gender (p= 0.008; OR 0.337; %95 CI 0.151-0.749), history of quinolone usage (p= 0.001; OR 0.170; %95 CI 0.059-0.494) and ESBL positive E. coli or Klebsiella spp. as responsible microorganisms (p= 0.038; OR 0.239; %95 CI 0.062-0.921) were identified as independent risk factors for quinolone resistance