The effect of the COVID-19 pandemic on the incidence and resistance of Gram-negative bacilli and antimicrobial consumption in the intensive care units of a referral hospital in Buenos Aires

•This time series study (July 2019 to March 2022) was undertaken to address changes in Gram-negative bacilli (GNB) incidence and antibiotic consumption in intensive care units.•Antibiotics against multidrug GNB signficantly increased, while other anti-GNB agents decreased.•These variations showed a significant correlation with the increase in overall GNB and in the amount of resistance mechanisms.•Health authorities must be prepared to respond rapidly and in a timely manner to resource demands in the face of possible future pandemics. There was a reported increase in the antimicrobial consumption in hospitals during the COVID-19 pandemic, accompanied by an increase in infections due to multidrug-resistant (MDR) bacteria. This retrospective time series study from intensive care units in Buenos Aires examined changes in antibiotic consumption (defined daily doses/1000 patients/day), the incidence of Gram-negative bacilli (GNB) and the mechanism of resistance. Antibiotics were categorised into group 1 (agents against 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 analysed and the Mann-Whitney test was performed to compare both periods. During the study period, GNB incidence, group 1 antibiotic consumption and resistance mechanisms increased, whereas antibiotics decreased in group 2. A significant positive correlation was seen 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), extended-spectrum beta lactamases (2 [1–2] vs. 6 [3–8] cases/month; P < 0.001) and metallo-beta-lactamases (0 [0–0] vs. 6 [1.75–8.5] cases/month; P < 0.001). During the COVID-19 pandemic, the rise in GNB incidence and the amount of resistance mechanisms significantly correlated with the increase in consumption of agents against MDR strains. [Display omitted]