Correlation Between Antimicrobial Consumption and Antimicrobial Resistance Rates of Acinetobacter species in a Tertiary Intensive Care Unit: A 10-year Time Series Analysis

INTRODUCTION: Antimicrobial resistance in Acinetobacter spp. is a growing concern in ICU settings. The connection between antimicrobial usage and the development of resistance is complex, including the selection of resistant strains due to the extensive use of broad-spectrum antimicrobials. This study analyzes trends in antimicrobial consumption and resistance rates of Acinetobacter spp. and their correlation in ICU settings.
METHODS: The study includes patients aged 18 and older hospitalized for more than 48 hours between 2007 and 2016. Repetitive culture results were excluded following the Centers for Disease Control and Prevention (CDC) 'Antimicrobial Use and Resistance Module' guidelines. Susceptibility testing was performed according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) rules. The resistance rate is expressed as the proportion of resistant isolates to total isolates. Anatomical Therapeutic Chemical (ATC) classification and the Defined Daily Dose (DDD) measurement units for each drug were assigned to the data. Antimicrobial consumption is expressed as the number of DDDs per 1,000 patient days. Trends in consumption and resistance were analyzed using an ARIMA model, and correlations were assessed using either Pearson or Spearman tests.
RESULTS: Consumption of ceftazidime, meropenem, sulfamethoxazole-trimethoprim, tigecycline, and colistin increased, while cefazolin, cefepime, cefuroxime, and amikacin decreased. Resistance to imipenem, meropenem, piperacillin-tazobactam, cefepime, netilmicin, cefoperazone-sulbactam, and tigecycline increased. Gentamicin, tobramycin, and sulfamethoxazole-trimethoprim susceptibility increased. There was a correlation between amikacin resistance and consumption of piperacillin-tazobactam, ceftazidime, colistin, meropenem, and tigecycline. Imipenem resistance correlated with consumption of meropenem, piperacillin-tazobactam, ceftazidime, and tigecycline. Meropenem resistance correlated with consumption of piperacillin-tazobactam and cefoperazone. Cefepime resistance correlated with consumption of netilmicin and sulfamethoxazole-trimethoprim. Netilmicin resistance correlated with consumption of colistin and netilmicin. Piperacillin-tazobactam resistance correlated with ceftazidime consumption.
DISCUSSION AND CONCLUSION: Monitoring antimicrobial resistance and its interaction with antimicrobial use is essential for effective antimicrobial stewardship programs.