Background: Intra-abdominal infection (IAI) is a challenging condition that needs both medical and surgical treatment and it is still associated with high morbidity and mortality rates. Fosfomycin is approved for use in combination therapy for IAIs. The aim of this study was to evaluate the impact of intravenous fosfomycin addition in a combination regimen for IAI treatment in an intensive care setting. Methods: We performed a retrospective, observational, monocentric study. We enrolled patients admitted to the ICU with IAIs from April 2022 to June 2024. Patients were divided into two groups: Group A, standard treatment; and Group B, combination therapy including fosfomycin. Primary endpoints were clinical response at 7 days and in-hospital mortality; moreover, a risk factor analysis for mortality was also performed. Results: In total, 104 patients were enrolled, 85 in Group A, and 19 in Group B. Groups were homogenous in regard to demographics, but clinical condition was slightly worst in Group B. Source control < 24 h was performed in 69.6% and 33.3% cases in Group A and Group B, respectively (p = 0.017). Clinical response on day 7 (81.2% vs. 73.7%, p = 0.675) and in-hospital mortality (27.1% vs. 47.2%, p = 0.145) were comparable. Univariate and multivariate analysis highlighted Charlson Comorbidity Index (CCI) (p = 0.04) and septic shock (p = 0.029) as risk factors, and effective empirical therapy (p = 0.04) as the protective factor; fosfomycin was not directly associated with outcome improvement. Conclusions: The outcome was comparable between groups; clinicians preferred to administer a combination regimen including fosfomycin in patients with statistically significant greater severity of illness and without early source control.

New beta-lactam/beta-lactamase inhibitor combinations (BL/BLICs) are licensed for Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae (KPC-Kp) infections. However, data regarding their efficacy against bacterial biofilms and the potential of synergistic combinations remain limited. This study evaluated their efficacy on planktonic and biofilm forms of KPC-Kp isolated from catheter-related bloodstream infections (CRBSIs), correlating findings with genomic and clinical data. Twelve KPC-3-harboring isolates (ST512, n = 7; ST307, n = 3; ST101, n = 2) were characterized via whole-genome sequencing. Ceftazidime/avibactam (CAZ/AVI), meropenem/vaborbactam (MEM/VAB), and imipenem/relebactam (IMI/REL) were tested alone or combined with fosfomycin (FOS), cefepime (FEP), meropenem (MEM), or imipenem (IMI) using checkerboard assays. All BL/BLICs alone showed significant, comparable efficacy against biofilm-producing strains. However, combination testing revealed heterogeneous synergistic profiles. CAZ/AVI combined with MEM, IMI, or FEP achieved 100% synergy in both planktonic and biofilm states. MEM/VAB-based combinations demonstrated consistent synergy (50–100%), whereas IMI/REL showed higher synergistic rates in biofilm than in planktonic forms. Conversely, FOS-based regimens were significantly less effective against biofilms. These findings provide a clinical rationale for selecting optimized dual regimens to eradicate biofilms, offering a critical therapeutic strategy to preserve vascular devices when catheter removal is unfeasible.

Infective endocarditis (IE) due to methicillin-susceptible Staphylococcus aureus (MSSA) still represents a clinical and therapeutic issue. Discrepancies between guidelines, clinical studies and clinical practice have already been highlighted, especially regarding daptomycin use in MSSA cases. The aim of this study was to evaluate daptomycin’s impact on outcomes in this setting. This was a retrospective observational study. We enrolled all patients with MSSA IE admitted from 2015 to 2023. Patients were divided into two groups according to daptomycin administration. We enrolled 76 patients, with 49 in group A (standard treatment) and 27 in group B (treated with daptomycin). The in-hospital crude mortality was 14.3% and 29.6% in group A and B, respectively (p = 0.191). Only heart failure was significantly associated with negative outcome in the univariate and multivariate analyses (OR 6.424, 95% CI, 1.680–24.559; p = 0.007). In this study population, daptomycin treatment for IE due to MSSA was not associated with a reduced mortality rate. Heart failure was the only independent risk factor associated with in-hospital mortality.