Strong association between ciprofloxacin use and ciprofloxacin resistance within a hospital

Abstract number: 1733_1595

Willemsen I., Heijneman A., Bogaers-Hofman D., Kluytmans J.

Objectives: In the last years the use of ciprofloxacin in our hospital has increased significantly. The objective of this study was to determine the increase of resistance over time and to determine if the density of antibiotic use correlates with the resistance in E. coli within individual hospital units.

Method: The density of the use of ciprofloxacin (cip), amoxicillin + clavulanic acid (amcl), 1st- and 2nd-generation cephalosporins (cef) and trimethoprim/Sulfamethoxazole (sxt) was measured in 6 consecutive one-day prevalence-surveys between 2001 and 2004. The susceptibility patterns from E. coli were obtained from the Laboratory Information System between 2003 and 2006. The percentage of resistance to cip, amcl, cef and sxt in E. coli isolates was calculated per unit and over time.

Results: A total of 4105 patients were included in the prevalence-surveys. 23% (938) of the patients were on antibiotics, of whom 12.8% (120) were treated with cip, 39.1% (367) with amcl, 13.2% (124) with cef and 5.7% (53) with sxt. 4790 E. coli susceptibility patterns were obtained from hospitalised patients. There was a significant increase of resistance over time for all antibiotics, except for SXT, and a significant correlation between the prevalence of use and the percentage of resistance for cip (R = 0.795, p = 0.006), amcl (R = 0.860, p = 0.001) and cef (R = 0.828, p = 0.003). For cip the urology unit rose above the other units with a use of 9.9% and a resistance rate of 19.8%. Also cip resistance showed the strongest increase over time.

Conclusion: This study shows that cip resistance is associated with the density of its use even on the micro-level of a hospital unit, and its use has the strongest association with resistance of all frequently used groups of antimicrobial-agents in the hospital.