Correlation between Antibiotic Consumption and Resistance of Invasive Streptococcus pneumoniae

There is a lack of long-term studies that correlate different metrics of antibiotic consumption and resistance of invasive S. pneumoniae. The present study aims to investigate the correlation between national outpatients total antibiotic, penicillin and broad spectrum penicillins consumption expressed in daily doses per 1000 inhabitants per day (DID) with the ATC/DDDs, WHO version of 2019 (new version) and 2018 (old version), number of prescriptions per 1000 inhabitants per year (RxIDs) and number of packages per 1000 inhabitant per day (PIDs) with the resistance of invasive S. pneumoniae in Slovenia in the period from 2000 to 2018. The prevalence of penicillin resistance of invasive S. pneumoniae decreased by 47.13%, from 19.1% to 10.1%. Decline of resistance showed the highest correlation (R = 0.86) between RxIDs followed by PID (R = 0.85) and resistance of S. pneumoniae. Higher correlation between total use of antibiotics expressed in DID WHO version 2019 (R = 0.80) than for WHO version 2018 (R = 0.78) was found. Very high (R = 0.84) correlation between use of beta-lactams expressed in PID, and RxIDs (R = 0.82) and reasonable (R = 0.59) correlation expressed in DIDs version 2019 was shown as well. The consumption of broad -spectrum penicillins (J01CA and J01CR02) expressed in PID (R = 0.72) and RxIDs (0.57) correlated significantly with the resistance of S. pneumoniae as well. A new finding of this study is that RxIDs correlated better with the resistance of S. pneumoniae than total consumption of antibiotics expressed in DID and significant correlations exist between use of broad-spectrum penicillins expressed in PID and RxIDs.