Correlation between antibiotic consumption and resistance of Gram-negative bacteria causing healthcare-associated infections at a university hospital in Taiwan from 2000 to 2009

Objectives: This study investigated the correlation between antibiotic consumption and antimicrobial resistance in Gram-negative bacteria causing healthcare-associated infections at a university hospital in Taiwan from 2000 to 2009. Methods: Disc susceptibility data of Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Serratia marcescens, Proteus spp., Pseudomonas aeruginosa, Acinetobacter spp., Stenotrophomonas maltophilia and other non-fermentative Gram-negative bacilli causing healthcare-associated infections were evaluated. Data on annual patient-days and annual consumption (defined daily doses per 1000 patient-days) of extended-spectrum cephalosporins, beta-lactam/beta-lactamase inhibitor combinations, carbapenems, aminoglycosides and fluoroquinolones were analysed. Results: The trend of total consumption of extended-spectrum cephalosporins, beta-lactam/beta-lactamase inhibitor combinations, carbapenems, aminoglycosides and fluoroquinolones significantly increased between 2000 and 2003 and remained stable between 2004 and 2009. The decreasing use of gentamicin and amikacin in recent years was associated with increasing susceptibility of E. coli, E. cloacae, S. marcescens and P. aeruginosa to gentamicin, as well as increasing susceptibility of P. aeruginosa to amikacin. The use of piperacillin/tazobactam was positively correlated with the prevalence of piperacillin/tazobactam-resistant E. coli and S. maltophilia. In contrast, the use of cefotaxime and piperacillin/tazobactam was negatively correlated with the prevalence of cefotaxime-resistant E. coli and piperacillin/tazobactam-resistant S. maltophilia, respectively. The consumption of fluoroquinolones was positively correlated with the rates of ciprofloxacin-resistant E. coli, piperacillin/tazobactam-resistant P. aeruginosa and ceftazidime-resistant S. maltophilia. Conclusions: The relationship between antibiotic prescription and the rates of resistance for Gram-negative bacteria is complicated; every type of antimicrobial agent or even individual agent can have distinct associations with different pathogens.