Relationships between antimicrobial use and antimicrobial resistance in Gram-negative bacteria causing nosocomial infections from 1991-2003 at a university hospital in Taiwan

Abstract

This study was conducted to evaluate the relationship between antimicrobial resistance and antimicrobial use in a university hospital in Taiwan. Disk 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 nosocomial infections were evaluated. Data on annual patient-days and annual consumption (defined daily dose (DDD) per 1000 patient-days) of extended-spectrum cephalosporins (cefotaxime, ceftriaxone, ceftazidime, flumoxef, cefepime and cefpirome), beta-lactam-beta-lactamase inhibitor combinations (ticarcillin/clavulanic acid and piperacillin/tazobactam), carbapenems (imipenem and meropenem), aminoglycosides (amikacin, gentamicin and tobramycin), fluoroquinolones (ciprofloxacin (oral and injectable) and oral levofloxacin and moxifloxacin) from 1991 to 2003 were analysed. Increasing trends of incidences of several of these bacteria causing all nosocomial infections or nosocomial bloodstream infections were noted from 1991 to 2003. The annual patient-days of the hospital significantly increased, from 360210 in 1991 to 672676 in 2002 (linear regression analysis, P < 0.05), but slightly decreased in 2003 (629168) owing to the severe acute respiratory syndrome epidemic in Taiwan. The rise in cefotaxime-resistant or ciprofloxacin-resistant E. coli and meropenem-resistant P. aeruginosa was significantly correlated with increased consumption of extended-spectrum cephalosporins, beta-lactam-beta-lactamase inhibitor combinations, carbapenems, fluoroquinolones and aminoglycosides (for ciprofloxacin-resistant E. coli and meropenem-resistant P. aeruginosa only) in the hospital (Pearson's correlation coefficient, r > 0.72 (or < -0.72) and P-value < 0.05). Increased ciprofloxacin-resistant K. pneumoniae and meropenem-resistant Acinetobacter spp. was significantly associated with the increased usage of extended-spectrum cephalosporins but not with the other four classes of antibiotics. This 13-year study in a hospital demonstrated significant changes in antimicrobial use, which may have affected antimicrobial resistance in certain Gram-negative bacteria at the hospital.

Fig. 1

Incidence (episodes per 10 000 discharged) of (A) all nosocomial infections and (B) nosocomial bloodstream infections caused by major Gram-negative bacilli isolated from patients treated at a university hospital in Taiwan from 1991–2003. NFGNB, non-fermentative Gram-negative bacilli.

Fig. 2

(A) Annual patient-days and (B) annual consumption (defined daily dose (DDD) per 1000 patient-days) of five classes of antimicrobial agents and resistance trends for five drug/organism combinations at a university hospital in Taiwan from 1991–2003.

Fig. 3

Yearly percentage of (A) cefotaxime-resistant Escherichia coli and (B) ceftazidime-resistant Pseudomonas aeruginosa observed between 1991 and 2003 and predicted values up to 2011 with 95% confidence intervals according to autoregressive integrated moving average (ARIMA) and transfer function models.