Ciprofloxacin use and susceptibility of Gram-negative organisms to quinolone and non-quinolone antibiotics

Objectives: A Trust strategy to reduce ciprofloxacin use was implemented at a University hospital. This study aimed to investigate whether the susceptibility of Gram-negative organisms (GNO) to alternative antimicrobials (co-amoxiclav, doxycycline, aztreonam, piperacillin/tazobactam, meropenem and gentamicin) changed, and whether there was any relationship between GNO susceptibility to these antimicrobials and ciprofloxacin usage. Methods: The first isolate of each GNO from blood cultures, sputum and urine of hospitalized adults, between January 2008 and August 2009, was included. Antibiotic usage and GNO susceptibility were investigated using linear regression. The association between defined daily dose/1000 occupied bed days (DDD/1000 OBD) and susceptibility was assessed using Pearson correlation and linear regression. Results: Ciprofloxacin use decreased significantly by 4.37 DDD/1000 OBD per month [95 % confidence interval (CI) 2.99, 5.75; P,0.001], while aztreonam and gentamicin use increased significantly (aztreonam: 0.22 DDD/ 1000 OBD increase per month; 95 % CI 0.10, 0.34; P0.001; gentamicin: 0.46 DDD/1000 OBD increase per month; 95 % CI 0.12, 0.79; P0.01). There was no change in meropenem, co-amoxiclav, doxycycline or piper-acillin/tazobactam use. When DDD/1000 OBD for all non-quinolone antimicrobials were pooled, use increased significantly by 3.33 DDD/1000 OBD per month (95 % CI 0.79, 5.87; P0.013). There were 5410 GNO isolates.