Utilisation of antimicrobials used to treat bacterial pneumonia in principal referral hospitals during the COVID-19 pandemic, Australia, 2020

Background Concerns have been raised internationally, regarding possible increased antimicrobial use during the COVID-19 pandemic and the potential impact on antimicrobial resistance. This analysis aimed to investigate hospital usage rates of broad-spectrum antibacterial agents used to treat community-acquired pneumonia (CAP) and/or hospital-acquired pneumonia (HAP) in Australian principal referral hospitals during 2020. Secondly, usage rates in Victoria were compared with equivalent national rates. Methods Monthly antimicrobial dispensing data for all 31 Australian principal referral hospitals were analysed for the period January 2019 to December 2020. Grams of antimicrobial agents used were converted into the World Health Organization (WHO) assigned metric 'Defined Daily Dose' (DDD). Using the hospital activity metric Occupied Bed Days (OBD), a standardised usage density rate was calculated (in units of DDD / 1,000 OBD). Results The typical expected seasonal trend in aggregate usage rates, for antibacterials used in the treat-ment of CAP, was not evident in 2020. Overall usage of doxycycline, azithromycin, amoxicillin and cefuroxime decreased in principal referral hospitals compared to 2019. Aggregated monthly usage rates for broad-spectrum agents used to treat HAP increased nationally, on average, by 5.0% in 2020 compared to 2019. Victoria's second COVID-19 wave (July-October 2020) coincided with higher usage rates of antibacterials used for CAP. Conclusion Public health interventions introduced to limit the spread of SARS-CoV-2 infections may have had unintended benefits on other respiratory infection rates. The drop in hospital usage of antibacterials typically used to treat CAP suggests that the number of cases of pneumonia acquired in the com-munity requiring hospitalisation was markedly reduced in 2020.