Pneumonia Characteristics in an Intensive Care Unit Setting during and after the COVID-19 Pandemic-A Single-Center Prospective Study.

Background: During and after the COVID-19 pandemic, there was a suspicion of varying rates of respiratory tract infections (RTIs), particularly pneumonia (PN). Methods : This research evaluated epidemiological indicators of community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP) in the COVID-19 pandemic and post-pandemic period, including pathogens, ventilator-associated pneumonia (VAP), selected risk factors, and PN mortality. Results : At 1740 patients, throughout the 22,774 patient-days (Pt-D) and 18,039 ventilation days (Vt-D), there were 681 PN cases (39.14%): CAP 336 (19.31%) and HAP 345 (19.83%). CAP caused by SARS-CoV-2 was diagnosed in 257/336 (76.49%) patients. The clinical manifestations of PNs were CAP with 336/681 (49.34%), VAP with 232/681 (34.07%), and non-ventilator HAP (NV-HAP) with 113/681 cases (16.59%). The incidence rate of CAP/1000 Pt-D has been over 3 times higher in the pandemic period of 2020-2021 (20.25) than in the post-pandemic period of 2022 (5.86), p = 0.000. Similarly, higher incidence rates of VAP/1000 Pt-D were found in the pandemic period ( p = 0.050). For NV-HAP, this difference was not statistically significant ( p = 0.585). VAP occurred more frequently in the group of patients with PN in the course of COVID-19 compared to patients without COVID-19 (52/234 [22.2%] vs. 180/1506 [11.95%]); ( p = 0.000). The most common CAP pathogen (during the pandemic) was SARS CoV-2 234/291 (80.4%), followed by MSSA/MRSA 8/291 (2.75%), whereas the most common VAP/NV-HAP pathogen was Acinetobacter baumannii XDR/MDR. The highest PN mortality was found in the patients with CAP caused by SARS-CoV-2 159/257 (61.87%). Conclusions : Pneumonias were diagnosed in nearly 40% of Intensive Care Unit (ICU) patients. Surveillance of pneumonias during the specific observation period was beneficial in the epidemiological and microbiological analysis of the ICU patients.