The COVID-19 pandemic has further highlighted the continuing threat of antimicrobial resistance (AMR) to global health and economic development. In the last two decades, AMR has raised increasing concern, with an estimated 4.95 million deaths globally due to bacterial AMR in 2019 alone. The aim of this study was to analyse the impact of the pandemic on the spread of multidrug-resistant organisms (MDROs) using data from the Hospital "P. Giaccone" in Palermo, comparing pre-pandemic and pandemic periods. This observational study involved adult patients who were discharged from the hospital between 01 January 2018 and 31 December 2021. Hospital Discharge Cards were linked with microbiological laboratory reports to assess MDRO isolations. SARS-CoV-2 positivity during hospitalisation was evaluated using the National Institute of Health surveillance system. A total of 58 427 hospitalisations were evaluated in this study. Half the patients were aged over 65 years (N=26 984) and most admissions were in the medical area (N=31 716). During the hospitalisation period, there were 2681 patients (5%) with MDROs isolations, and 946 patients (2%) were positive for SARS-CoV-2. Multivariable analyses showed that during 2020 and 2021, there was a significantly increased risk of isolation of Staphylococcus aureus, Acinetobacter baumannii, and Klebsiella pneumoniae. Age, weight of the Diagnosis-Related Group (DRG), wards with higher intensity of care, and length-of-stay were associated with a higher risk of MDRO isolation. This study provides new insights into the impact of the COVID-19 pandemic on MDRO isolation and has important implications for infection control and prevention efforts in healthcare facilities. Age, DRG-weight, and longer hospital stays further increased the risk of MDRO isolation. Thus, it is imperative to improve and follow hospital protocols to prevent healthcare-associated infections.

Bloodstream infections (BSIs) and sepsis are a major cause of morbidity and mortality. Appropriate early antibiotic therapy is crucial for improving the survival of patients with sepsis and septic shock. T2 magnetic resonance (T2MR^®) technology may enable fast and sensitive detection of ESKAPEc pathogens directly from whole-blood samples. We aimed to evaluate concordance between the T2Bacteria^® Panel and standard blood culture and its impact on antibiotic therapy decisions. We conducted a single-centre retrospective study on patients with sepsis-induced hypotension or septic shock admitted to general, post-operative/neurosurgical, and cardiothoracic Intensive Care Units who were tested with the T2Bacteria^® Panel from January 2021 to December 2022. Eighty-five consecutively admitted patients were included, for a total of 85 paired tests. A total of 48 ESKAPEc pathogens were identified by the T2Bacteria^® Panel. The concordance rate between the T2Bacteria^® Panel and blood cultures was 81% (69/85), with 20 concordant-positive and 49 concordant-negative cases. For the 25 microorganisms grown from accompanying blood cultures, blood pathogen coverage by the T2Bacteria^® Panel was 88%. In this cohort of severely ill septic patients, the T2Bacteria^® Panel was highly concordant and was able to detect more ESKAPEc pathogens, with a significantly shorter turn-around time compared to conventional blood cultures. The T2Bacteria^® Panel also significantly impacted decisions on antibiotic therapy.

Background: The advent and continuous improvement in antiretroviral therapy (ART) have profoundly altered the clinical course of HIV infection, shifting the focus from AIDS-related complications to the management of age-related comorbidities and non-AIDS-related hospitalizations. In this evolving context, optimizing ART is essential, with genotypic resistance testing (GRT), particularly through next-generation sequencing (NGS), playing a pivotal role. Methods: This multicenter, retrospective cross-sectional study investigated HIV-1 subtypes, resistance mutations, and drug resistance profiles among 367 people living with HIV (PLWH) in Sicily, based on 384 GRTs performed at the Microbiology Laboratory of the University Hospital of Palermo. Results: Subtype B was the most prevalent (50%), followed by circulating recombinant forms (30%). Among treatment-naïve individuals, resistance-associated mutations were infrequent, with prevalence rates of 0.4% for NRTIs, 5.5% for NNRTIs, 1.3% for PIs, and 0.8% for INIs. Conversely, treatment-experienced individuals showed significantly higher resistance rates, especially to NRTIs (16.3%), NNRTIs (10.6%), and INIs (9.6%). No significant differences in resistance patterns were observed between B and non-B subtypes. Conclusions: This study provides the first regional overview of HIV drug resistance across Sicily. Despite the detection of resistance-associated mutations, the overall prevalence of clinically relevant resistance, particularly to currently recommended therapies, remains low, especially among treatment-naïve individuals.

Background: Rapid antimicrobial susceptibility testing (RAST) allows early detection of resistance directly from positive blood cultures, potentially improving outcomes in bloodstream infections (BSIs). We evaluated the performance of EUCAST RAST for Gram-negative ESKAPEEc pathogens and characterized carbapenemase genes in carbapenem-resistant Klebsiella pneumoniae (CRKP). Methods: A total of 354 positive blood cultures were screened, including 51 monomicrobial Gram-negative ESKAPEEc isolates. RAST results at 4, 6, 8, and 16–20 h were compared with standard antimicrobial susceptibility testing (AST) obtained using the BD Phoenix™ system. Categorical agreement (CA) and error frequency were calculated. Multiplex PCR and Sanger sequencing were performed on 15 CRKP isolates to identify carbapenemase genes and allelic variants. Results: 51 Gram-negative ESKAPEEc isolates met the inclusion criteria for RAST (15 E. coli, 19 K. pneumoniae, 11 A. baumannii, and 6 P. aeruginosa). Overall performance varied markedly by species and antibiotic. E. coli showed frequent unreadable or ATU zones at early timepoints and wide CA variability (50–100%), with high very major error (VME) rates for AMP, TZP, and CAZ, particularly at 6–8 h. K. pneumoniae displayed consistently high CA (mostly 100%) for carbapenems, CAZ, and TZP. A. baumannii demonstrated excellent agreement (100% for most agents), except for GEN at 6–8 h. P. aeruginosa could be evaluated only at 16–20 h, showing high CA for AMK, CAZ, and CIP; lower CA for MEM (83%); non-calculable CA for IMI due to universal ATU readings; and a CA value of 0% for TZP due to the predominance of the ATU results. VMEs ranged from 0% to 26.1% across species and reading times, but carbapenems did not generate VMEs. Molecular analysis revealed bla_KPC in 66.7%, bla_NDM in 46.7%, and bla_OXA-48 in 33.3% of isolates, with co-occurrence in several strains. Sequencing identified bla_KPC-2 and bla_NDM-1 as the predominant variants, with one isolate harboring bla_NDM-5. Conclusions: EUCAST RAST markedly accelerates susceptibility reporting from positive blood cultures, but its accuracy is species- and time-dependent. Performance was excellent for K. pneumoniae (including CRKP) and A. baumannii and acceptable for P. aeruginosa at 16–20 h. In contrast, E. coli showed frequent ATU results at early timepoints and high ME/VME rates, making readings before 8 h unreliable for clinical decisions. Overall, RAST can effectively support rapid antimicrobial stewardship when species-specific limitations are recognized, and early-timepoint results are interpreted with caution.

Introduction Acinetobacter baumannii is recognized by the World Health Organization (WHO) as one of the ESKAPE priority pathogens because of its environmental persistence and ability to acquire antimicrobial resistance. Carbapenem-resistant A. baumannii (CRAb) has been included in the WHO Global Priority List of Antibiotic-Resistant Bacteria since 2017 and remains a critical threat. In Europe, CRAb is responsible for a substantial burden of healthcare-associated infections and mortality, particularly among critically ill patients. Objectives To evaluate temporal trends in antimicrobial resistance among clinical isolates of Acinetobacter baumannii collected at the Microbiology Laboratory of the University Hospital “Paolo Giaccone” of Palermo over a 13-year period (2013–2025). Methods A retrospective analysis was conducted on all clinical isolates of A. baumannii collected between 2013 and 2025 (N = 3,010). One isolate per patient was included. Data collected comprised year of isolation, patient demographics (age and sex), hospital ward (Intensive Care Unit/Emergency, Medical Area, Surgical Area), and biological sample type. Antimicrobial susceptibility testing was performed against polymyxins, fluoroquinolones, aminoglycosides, and carbapenems. Isolates were classified as multidrug-resistant (MDR) when resistant to at least three antimicrobial classes. Comparisons between MDR and non-MDR isolates were performed using chi-square or Fisher’s exact tests for categorical variables and the Kruskal–Wallis test for age. To identify independent predictors of MDR isolation and evaluate temporal variability, a mixed-effects logistic regression model was applied, with isolates nested within years. Age, sex, clinical area, and sample type were included as fixed effects, while year of isolation was modelled as a random effect. Results were reported as adjusted odds ratios (ORs) with 95% confidence intervals (95% CIs). Results Among the 3,010 isolates analyzed, 2,727 (90.6%) were classified as MDR. Patients were predominantly male (60.3%), with a mean age of 71.0 ± 15.7 years; 71.4% were aged 65 years or older. Most isolates originated from Intensive Care/Emergency Units (43.8%), followed by Medical (33.9%) and Surgical Wards (21.0%). Resistance rates remained consistently high throughout the study period, reaching 95.8% for carbapenems, 95.1% for fluoroquinolones, and 91.0% for aminoglycosides. Polymyxin resistance remained low (1.6%). Univariable analyses did not identify significant associations between patient or clinical characteristics and MDR status. In the mixed-effects model, age emerged as the only independent predictor of MDR isolation (OR 1.01; 95% CI 1.00–1.02; p = 0.019). Significant between-year variability was observed (random intercept SD = 0.404; 95% CI 0.046–0.526). Year-specific analyses showed a significantly increased probability of MDR isolation in 2020, whereas significantly lower-than-expected odds were observed in 2022 and 2023. Conclusions The observed temporal variability suggests that healthcare-system factors, beyond individual patient characteristics, influenced MDR A. baumannii circulation. The increase observed in 2020 coincided with the COVID-19 pandemic, characterized by increased intensive care admissions, broad-spectrum antibiotic use, prolonged mechanical ventilation, and critical care overcrowding. Conversely, the reduction observed in 2022–2023 may reflect strengthened infection prevention and control measures and reduced antibiotic selective pressure associated with declining COVID-19-related critical care admissions.