Hospital-acquired infections (HAIs) are a global public health concern. As the COVID-19 pandemic continues, its contribution to mortality and antimicrobial resistance (AMR) grows, particularly in intensive care units (ICUs). A two-year retrospective study from April 2019–April 2021 was conducted in an adult ICU at the Hospital for Infectious and Tropical Diseases, Belgrade, Serbia to assess causative agents of HAIs and AMR rates, with the COVID-19 pandemic ensuing halfway through the study. Resistance rates >80% were observed for the majority of tested antimicrobials. In COVID-19 patients, Acinetobacter spp. was the dominant cause of HAIs and more frequently isolated than in non-COVID-19 patients. (67 vs. 18, p = 0.001). Also, resistance was higher for imipenem (56.8% vs. 24.5%, p < 0.001), meropenem (61.1% vs. 24.3%, p < 0.001) and ciprofloxacin (59.5% vs. 36.9%, p = 0.04). AMR rates were aggregated with findings from our previous study to identify resistance trends and establish empiric treatment recommendations. The increased presence of Acinetobacter spp. and a positive trend in Klebsiella spp. resistance to fluoroquinolones (R² = 0.980, p = 0.01) and carbapenems (R² = 0.963, p = 0.02) could have contributed to alarming resistance rates across bloodstream infections (BSIs), pneumonia (PN), and urinary tract infections (UTIs). Exceptions were vancomycin (16.0%) and linezolid (2.6%) in BSIs; tigecycline (14.3%) and colistin (0%) in PNs; and colistin (12.0%) and linezolid (0%) in UTIs. COVID-19 has changed the landscape of HAIs in our ICUs. Approval of new drugs and rigorous surveillance is urgently needed.

Antimicrobial resistance (AMR) is a global concern, and antibiotic use has risen throughout the COVID-19 pandemic. Up to 75% of COVID-19 patients are treated with antibiotics despite little evidence for their use. A retrospective study from 6 March 2020 (the start of the pandemic in Serbia) to 31 December 2021 was conducted at the Clinic for Infectious and Tropical Diseases, University Clinical Centre of Serbia. In total, 523 patients with a microbiological diagnosis of COVID-19 were included. Patient data were analysed, including antibiotic use before and after admission. Pre-admission use of antibiotics for COVID-19 treatment was documented in more than half of patients (58.1%), of which a third (34.1%) used more than one antibiotic. Macrolides, cephalosporins, and fluoroquinolones were mainly used, most frequently among patients aged between 31–45 years (75.2%). Prior antibiotic use was associated with a longer duration of illness at admission (8.8 vs. 5.7, p < 0.001), oxygen therapy upon admission (27.6% vs. 16.0%, p = 0.002), and a lower vaccination rate (60.7% vs. 50.7%, p = 0.04). When hospitalised, 72.1% of patients received antibiotics, primarily cephalosporins (71.9%). Significant efforts are needed to reduce antibiotic use in the community and improve prescribing rates by healthcare professionals.

Introduction/Aim: So far, the COVID-19 pandemic has seen four major epidemic waves that have affected more than 753 million people. Epidemiological studies have confirmed variability of clinical presentation of SARS-CoV-2 infection in these epidemic waves. During this period, virus mutations have contributed to greater challenges regarding treatment and prevention. The aim of the study is to determine the differences in clinical presentation, laboratory parameters, as well as the treatment outcome of patients suffering from COVID-19 during four different epidemic waves caused by different genotypic and phenotypic variants of SARS-CoV-2. Material and Methods: We conducted retrospective study in which data were collected from hospitalized patients at the University Clinical Centre of Serbia Clinic for Infectious and Tropical Diseases in the period between March 1, 2020 and December 1, 2021. Statistical analyses, socio-epidemiological, clinical, radiographic and laboratory characteristics of patients through different epidemic waves of COVID-19 were compared. Results: The study included 523 patients. Elevated body temperature was the first and the most common symptom of COVID-19 infection in all 4 epidemic waves, whereas cough and malaise were most common symptoms in the fourth wave. Cough was second most common symptom in third wave (p<0.05), following elevated body temperature, whereas malaise was second most common in the second wave. Diarrhea and nausea were significantly more common in the fourth wave compared to the previous waves (p=0.04 and p=0.02). Conclusion: Highest values of inflammatory biomarkers were found in the second and the fourth wave. The fourth wave was characterized by the largest number of hospitalized patients, and it represented the peak of the pandemic. Treatment options varied through the waves, and corticosteroid use was most common during the fourth epidemic wave in hospital conditions.