Detection of volatile organic compounds as new paradigm to accelerate antimicrobial susceptibility testing: performance evaluation of VITEK® REVEAL™.

OBJECTIVES: The measurement of VOCs release in the headspace of a bacterial culture represents a new approach to rapidly assess antimicrobial susceptibility. Herein, we evaluated the diagnostic performance of the VITEK® REVEAL™ system directly from a collection of Gram-negative positive blood cultures. MATERIALS AND METHODS: One hundred and twenty-eight positive blood cultures were included in the analysis (Enterobacterales, n = 95; Pseudomonas aeruginosa, n = 21; Acinetobacter baumannii complex, n = 12). Samples were processed using VITEK® REVEAL™ according to the manufacturer's recommendations, and MICs of 22 antimicrobials were compared with those obtained using reference methods. Categorical agreement (CA), essential agreement (EA) and categorical errors were calculated. RESULTS: Overall, 2220 strain/antibiotic pair combinations were analysed. Of these, most were classified as resistant by reference antimicrobial susceptibility testing (1091/2220; 48.7%). The overall CA and EA were 97.6% and 97.7%, respectively. CA ranged from 97.5% in Enterobacterales to 97.9% in both P. aeruginosa and A. baumannii complex. The overall number of categorical discrepancies were: 18 very major errors (1.6%), 13 major errors (1.2%) and 22 minor errors (2.4%). EA ranged from 95.2% in P. aeruginosa to 98.1% in Enterobacterales. Screening test for ESBL phenotype was positive, indeterminate and negative in 13.7%, 32.6% and 27.4% of Enterobacterales isolates tested by both VITEK® REVEAL™ and the reference method, showing 100% CA. CONCLUSIONS: VITEK® REVEAL™ represents a reliable tool to obtain antimicrobial susceptibility results of the main Gram-negative species directly from positive blood cultures with time to results of less than 8 h.

Extracellular microRNAs induce dendritic cell-dependent joint inflammation and potentiate osteoclast differentiation via TLR7/8 engagement.

OBJECTIVES: Monocyte-derived dendritic cells (DCs) are key players in the induction of inflammation, autoreactive T cell activation and loss of tolerance in rheumatoid arthritis (RA), but the precise mechanisms underlying their activation remain elusive. Here, we hypothesized that extracellular microRNAs released in RA synovial fluids may represent a novel, physiological stimulus triggering unwanted immune response via TLR8-expressing DC stimulation. METHODS: Human monocyte-derived DCs were stimulated with a mixture of GU-rich miRNAs upregulated in RA tissues and released in synovial fluids (Ex-miRNAs). Activation of DCs was assessed in terms of NF-κB activation by Western blot, cytokine production by ELISA, T cell proliferation and polarization by allogeneic mixed lymphocyte reaction. DC differentiation into osteoclasts was evaluated in terms of tartrate-resistant acid phosphatase production and formation of resorption pits in dentine slices. Induction of joint inflammation in vivo was evaluated using a murine model of DC-induced arthritis. TLR7/8 involvement was assessed by specific inhibitors. RESULTS: Ex-miRNAs activate DCs to secrete TNFα, induce joint inflammation, start an early autoimmune response and potentiate the differentiation of DCs into aggressive osteoclasts. CONCLUSIONS: This work represents a proof of concept that the pool of extracellular miRNAs overexpressed in RA joints can act as a physiological activator of inflammation via the stimulation of TLR8 expressed by human DCs, which in turn exert arthritogenic functions. In this scenario, pharmacological inhibition of TLR8 might offer a new therapeutic option to reduce inflammation and osteoclast-mediated bone destruction in RA.

Antimicrobial Efficacy of a Vegetable Oil Plasticizer in PVC Matrices.

The growing prevalence of bacterial and viral infections, highlighted by the recent COVID-19 pandemic, urgently calls for new antimicrobial strategies. To this end, we have synthesized and characterized a novel fatty acid epoxy-ester plasticizer for polymers, named GDE. GDE is not only sustainable and user-friendly but also demonstrates superior plasticizing properties, while its epoxy components improve the heat stability of PVC-based matrices. A key feature of GDE is its ability to confer antimicrobial properties to surfaces. Indeed, upon contact, this material can effectively kill enveloped viruses, such as herpes simplex virus type 1 (HSV-1) and the ß-coronavirus prototype HCoV-OC43, but it is ineffective against nonenveloped viruses like human adenovirus (HAdV). Further analysis using transmission electron microscopy (TEM) on HSV-1 virions exposed to GDE showed significant structural damage, indicating that GDE can interfere with the viral envelope, potentially causing leakage. Moreover, GDE demonstrates antibacterial activity, albeit to a lesser extent, against notorious pathogens such as Staphylococcus aureus and Escherichia coli. Overall, this newly developed plasticizer shows significant potential as an antimicrobial agent suitable for use in both community and healthcare settings to curb the spread of infections caused by microorganisms contaminating physical surfaces.