The drug resistance index as an indicator for the impact of antimicrobial stewardship program implementation

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To assess the changes in the drug resistance index (DRI), a composite measure that combines the level of resistance of individual pathogens with the extent of antimicrobial drugs consumption in a multidisciplinary hospital, after implementation of the antimicrobial stewardship program (AMSP) and during COVID-19 pandemic.

Material and methods

In a retrospective study, we analyzed the medical records of patients hospitalized from the 4th quarter of 2018 to the 4th quarter of 2020. We used data on consumption of antimicrobial drugs and resistance of identified pathogens to calculate DRI over aforementioned period. AMSP was implemented in the 1st quarter of 2019, whereas the hospital was repurposed for the treatment of COVID-19 patients in the 2nd quarter of 2020.


Over studied period, a total of 1,425 etiologically significant patho gens were isolated from 593 patients (average age 67.3 ± 9.87 years, 324 females), mostly K. pneumoniae и A. baumanii. DRI for A. baumanii и P. aeruginosa remained high during the study. DRI for K. pneumo niae decreased from 0.81 to 0.66 after implementation of AMSP (p<0.05) and increased up to 0.90 during COVID-19 pandemics. DRI for E. coli also increased during COVID-19 pandemic from 0.38 up to 0.67 (p<0.05). AMSP was associated with reduction in DRI for S. aureus from 0.43 to 0.20 and for E. faecium from 0.54 to 0.38 (p<0.05 in both cases). During COVID-19 pandemics, DRI for S. aureus increased up to 0.60 (р<0.05).


Implementation of AMSP contributed to reduction in DRI for certain key pathogens, whereas repurposing of the hospital for COVID-19 patients was associared with negative changes in their resistance patterns.

Key words

Antimicrobial stewardship program, drug resistance index, antibiotic resistance, nosocomial infections.