The effect of the COVID-19 pandemic on the incidence and resistance in Gram-negative bacilli and antimicrobial consumption in the Intensive Care Units of a referral hospital in Buenos Aires

Abstract

A retrospective time series study from Intensive Care Units, to address changes in antibiotic consumption (DDD/1000 patients/day), the incidence of Gram-negative bacilli (GNB) and the mechanism of resistance. Antibiotics were categorised in group 1 (agents against multi-drug resistant MDR GNB) and group 2 (agents against non-MDR infections). Bacteriological samples included respiratory samples and blood cultures. Periods were divided into pre-pandemic (July 2019 to March 2020) and pandemic (April 2020 to March 2022). Correlation coefficients (r) were analyzed and Mann-Whitney test was performed to compare both periods. During the study period, GNB incidence, group 1 antibiotics consumption and resistance mechanisms increased, whereas group 2 antibiotics decreased. A significant positive correlation was observed between the consumption of antibiotics in group 1 and the incidence of GNB (r=0,63; p<0.001) and resistance (r=0,52; p=0.002). Significant differences were found between pre-pandemic and pandemic periods regarding the medians of group 1 consumption (520 [408-570] vs 753 [495-851] DDD/1000 patients/day; p=0.029); incidence of GNB (12 [10-13] vs 43 [25-52.5] cases/month; p<0.001) and resistance mechanisms (5 [4-8] vs 17 [10-25] cases/month; p<0.001), ESBL (2 [1-2] vs 6 [3-8] cases/month; p<0.001) and MBL (0 [0-0] vs 6 [1.75-8.5] cases/month; p <0.001). During the pandemic, the rise of GNB incidence and in the amount of resistance mechanisms significantly correlated with the increase in consumption of agents against MDR strains.