Despite being implicated in a wide spectrum of community- and healthcare-acquired infections, anaerobes have not yet been incorporated into systematic surveillance programs in Europe. We conducted a multicentre retrospective observational study analysing all anaerobic strains isolated from blood cultures in 44 European Hospital Centres over a 4-y period (2020-2023). Diagnostic approach, epidemiology, and antimicrobial susceptibility according to EUCAST v. 15.0 were investigated. Our study included 14,527 anaerobes, most of which were Gram-positive (45%) or Gram-negative (40%) bacilli. MALDI-TOF coupled to mass spectrometry was the most widely used tool for species identification (98%). Antimicrobial susceptibility testing was performed in the vast majority of centres, using mostly gradient diffusion strip (77%) and disk diffusion (45%) methods according to EUCAST guidelines. The most prevalent species were Cutibacterium acnes (18.7%), Bacteroides fragilis (16.3%), Clostridium perfringens (5.3%), Bacteroides thetaiotaomicron (4.2%), Fusobacterium nucleatum (3.5%), and Parvimonas micra (3.4%). C. acnes showed high resistance to benzylpenicillin (18%), clindamycin (39%), and imipenem (19% and 13% by MIC methods and disk diffusion, respectively). B. fragilis showed high resistance to amoxicillin/clavulanate (24%), piperacillin/tazobactam (22% and 14% by MIC methods and disk diffusion, respectively), clindamycin (22% by both MIC methods and disk diffusion), meropenem (13%), and metronidazole (10%, only by disk diffusion). A similar resistance pattern was observed in B. thetaiotaomicron, Bacteroides ovatus, and Parabacteroides distasonis. C. perfringens showed high resistance to clindamycin (69% and 45% by MIC methods and disk diffusion, respectively), while benzylpenicillin and metronidazole maintained over 90% activity. F. nucleatum showed high resistance to benzylpenicillin (11%), while Fusobacterium necrophorum showed alarming rates of resistance to clindamycin (12%), meropenem (16%) and metronidazole (11%). This study presented an up-to-date analysis of the diagnostics and epidemiology of anaerobic bacteria in Europe, providing insights for future comparative analyses and the development of antimicrobial diagnostic and management strategies, as well as the optimization of current antibiotic treatments.

This study evaluated the antimicrobial efficacy of cefiderocol and various forms of silver (ionic and nanoparticulate) as potential components of wound-dressing reagents against both reference and multidrug-resistant (MDR) Gram-negative bacteria. The anticipated synergistic effect between cefiderocol and nanosilver was not consistently observed; in fact, for reference strains, the combination was less effective than cefiderocol alone. However, in MDR and cefiderocol-resistant A. baumannii strains, combining both agents enhanced antibacterial efficacy. Notably, the effectiveness of silver did not increase with concentration, and low or medium nanosilver concentrations were often more effective. Mechanistically, high concentrations of silver may antagonize cefiderocol’s action by inhibiting bacterial surface proteins involved in siderophore-mediated uptake. Generalized linear modeling confirmed that the strain type, silver form, concentration, and their interactions significantly influenced inhibition zones. These findings highlight the importance of agent selection, concentration, and formulation in designing effective antimicrobial wound dressings. They also suggest that further research is needed to optimize such combination therapies for clinical use.

Background/Objectives: Certain yeast species are recognized as significant opportunistic pathogens, capable of causing severe systemic infections, particularly in immunocompromised individuals or those with disrupted physiological barriers. The rising incidence of invasive candidiasis associated with vascular infections poses a significant clinical challenge due to the high mortality rates and the limited efficacy of conventional antifungal therapies. The formation of resilient biofilms on vascular catheters by species such as Candida albicans and Nakaseomyces glabratus further complicates treatment, often leading to persistent fungemia and necessitating device removal. With the emergence of multidrug-resistant (MDR) strains, there is a critical need for new therapeutic agents like rezafungin—a novel, long-acting echinocandin with potential enhanced antibiofilm activity. Methods: This study tested susceptibility to antimycotics available in Poland (fluconazole, voriconazole, posaconazole, amphotericin B, anidulafungin, caspofungin, and micafungin) using the commercial Micronaut-AM test (Bruker, Bremen, Germany). Susceptibility to rezafungin (Angene Chemical, Great Britain) was determined using the microdilution method in RPMI medium, recommended by European Committee on Antimicrobial Susceptibility Testing (EUCAST), with amphotericin B as a control compound. We evaluated the biofilm-forming capacity and the in vitro activity of rezafungin against 42 clinical isolates of Candida albicans and Nakaseomyces glabratus recovered from positive blood cultures. Results: The obtained minimum inhibitory concentration (MIC) values suggest rezafungin activity against all the tested isolates, with different susceptibility to echinocandins and other antifungal drugs (azoles, amphotericin B) currently registered and used in Poland. The MIC readings for rezafungin were in the range of 0.008–0.5, with MIC₅₀ = 0.016 and MIC₉₀ = 0.25. The isolates were categorized as low, moderate, or strong biofilm producers according to established Stepanović criteria (cut-off values OD₆₃₀ < 0.019, 0.19–0.38, >0.38, respectively). Furthermore, the higher minimum biofilm eradication concentrations (MBECs) compared to the minimum inhibitory concentrations (MICs) of planktonic cells confirm the reduced activity of rezafungin against biofilms. Conclusions: Critically, the high antibiofilm efficacy at clinically achievable concentrations suggests that rezafungin shows promise as a potential therapeutic option for catheter-related candidemia, though further clinical studies are needed. Furthermore, the high susceptibility of N. glabratus isolates—a species frequently associated with azole resistance—suggests rezafungin may be a valuable addition to the existing antifungal arsenal of multidrug-resistant (MDR) fungal infections in hospital settings. Future research should focus on in vivo models to confirm if these in vitro results translate into accelerated clearance of vascular biofilms.

The human microbiome is comprised of a complex ecosystem of microorganisms and considerably influences the func­tioning of the immune system. Recent research has demonstrated a significant impact of the microbiome on cancer immunotherapy, particularly in terms of enhancing or undermining its therapeutic efficacy. This abstract examines the bidirectional relationship between the microbiome and immune responses, especially how specific microbial com­munities can affect immune modulation, tumor progression and treatment outcomes in cancer immunotherapy. It has been demonstrated that specific gut bacteria may enhance the efficacy of immune checkpoint inhibitors and adoptive cell transfer therapies as they promote Th1 polarization and improve T-cell responses. The insight into mechanisms underlying microbiome-immune interactions breaks new ground for innovative strategies in cancer immunotherapy, for example personalized adjunct therapies. This perspective underscores the necessity of integrating microbiome profiling into oncological practice to optimize immunotherapeutic strategies and improve patient outcomes. Keywords: human microbiome microbiota immune system immunomodulation