Persistent carbapenem resistance in mechanically ventilated ICU patients: A before-and-after analysis of the COVID-19 surge.

Objective: How did the antimicrobial resistance profile of critically ill patients evolve before, during, and after COVID-19 surge periods?

Methods: We retrospectively analysed all critically ill mechanically ventilated adult patients admitted to eight Brazilian hospitals from January 1st, 2018, to April 30th, 2023. We stratified the patients into three periods based on their admission date: pre-surge (Jan 01/2018-Mar 01/2020), surge (Mar 01/2020 - Oct 01/2021), and post-surge (after Oct 01/2021). We compared the proportion of positive cultures, prevalence of pathogens, and resistance rates across periods using the rate ratios (RR) and their 95% confidence intervals (95% CI).

Results: We analysed 9,780 ICU patients: 3,718 were in the pre-surge, 3,815 in the surge, and 2,247 in the post-surge period. Patients in the surge period were younger (median: 70 vs. 74 pre-surge vs. 75 post-surge) and presented a higher duration of invasive mechanical ventilation (median 7 vs. 5 days). The utilisation of blood and respiratory cultures increased throughout periods (56.9 pre-surge vs. 69.4 surge vs. 70.4 patients/1,000 patient days post-surge). The isolation of carbapenem-resistant gram-negative bacteria increased during the surge (RR [95% CI]: 1.8 [1.5-2.2], compared to pre-surge), decreased in post-surge (RR [95% CI]: 0.72 [0.6-0.9], and remained higher than pre-surge (RR [95% CI]: 1.3 [1.0-1.6]). Resistance rates for Pseudomonas aeruginosa reduced from 32% in pre- to 23% post-surge, whereas Klebsiella pneumoniae doubled during the surge, 26% to 52%, and remained higher than pre-surge.

Conclusion: Carbapenem resistance increased during the surge period. Although it decreased post-surge, it remained higher than the rates observed before the pandemic.