Transient receptor potential ankyrin 1 (TRPA1) channels are expressed on the surface of different cell types, including immune cells. However, TRPA1’s role in the context of innate and adaptive immune responses has not been fully elucidated so far. In this study, we aimed at investigating the expression and function of TRPA1 channels on NK cells. Among NK cells, TRPA1 was highly expressed by the CD56^dimCD16⁺ subpopulation, but not by CD56^brightCD16⁻ cells, as detected by FACS. TRPA1 activation with the potent ligand allyl isothiocyanate (AITC) induces intracellular calcium flux in CD56^dimCD16⁺ cells, which was prevented by the TRPA1 antagonist HC-030031. AITC treatment increased the membrane around NKp44 and strongly decreased CD16 and CD8 expression, while CD158a, CD159a, NKG2d, NKp46 were substantially unaffected. Importantly, AITC increased the granzyme production and CD107 expression and increased NK cell-mediated cytotoxicity towards the K562 cell line and two different melanoma cell lines. In parallel, TRPA1 activation also plays regulatory roles by affecting the survival of NK cells to limit uncontrolled and prolonged NK cell-mediated cytotoxicity. Our results indicate that the activation of TRPA1 is an important regulatory signal for NK cells, and agonists of TRPA1 could be used to strengthen the tumor response of the immune system.

Background: Multi-drug-resistant Gram-negative bacteria producing metallo-β-lactamase are an increasing concern. Here, we described three cases of infection due to difficult-to-treat and drug-resistant P. aeruginosa producing metallo-β-lactamases, which were successfully treated with antibiotic combination of cefiderocol plus imipenem–relebactam, and reported on the molecular and epidemiological features of the isolates and the in vitro synergistic effects of different antibiotic combinations guiding antibiotic treatment. Patients and methods: Three P. aeruginosa strains were isolated from respiratory or blood cultures of three different patients. Minimum inhibitory concentrations breakpoints were interpreted according to EUCAST recommendations. Next-generation sequencing data were used for in silico identification of resistance genes and sequence types and for core genome multi-locus sequence typing analysis. The fractional inhibitory concentration index was performed as a measure of synergy of cefiderocol plus imipenem and imipenem–relebactam. Results: The three isolates exhibited different multi-drug-resistant and molecular profiles carrying blaIMP-13 (imipenemase metallo-β-lactamase-13) (isolates named Pse-1 and Pse-3) and blaVIM-2 (Verona integron-encoded metallo-β-lactamase-2) (isolate Pse-2). Typing showed that the isolates did not cluster and belonged to different sequence types. The E-test method showed the presence of synergy of cefiderocol in combination with imipenem–relebactam in the two P. aeruginosa isolates producing IMP-13 (Pse-1 and Pse-3). No synergy was observed in the isolate producing VIM-2 (Pse-2). Conclusions: Cefiderocol in association with imipenem–relebactam exhibited a synergistic effect against IMP-producing P. aeruginosa isolates. Further studies with a range of drugs and an expanded number of isolates are required to ascertain potential novel synergistic associations and the clinical utility of the fractional inhibitory concentration index.

Klebsiella pneumoniae strains that are resistant to multiple drugs (KPMDRs), which are often acquired in hospital settings and lead to healthcare-associated infections, pose a serious public health threat, as does hypervirulent K. pneumoniae (hvKp), which can also cause serious infections in otherwise healthy individuals. The widespread and often unnecessary use of antibiotics seen during the recent COVID-19 pandemic has exacerbated the challenges posed by antibiotic resistance in clinical settings. There is growing concern that hypervirulent (hvKp) strains may acquire genes that confer antimicrobial resistance, thus combining an MDR profile with their increased ability to spread to multiple body sites, causing difficult-to-treat infections. This study aimed to compare resistance and virulence profiles in KPC-3-producing K. pneumoniae isolates collected over four years (2020–2023). A genome-based surveillance of all MDR CRE-K. pneumoniae was used to identify genetic differences and to characterize the virulence and resistance profiles. Our results provide a picture of the evolution of resistance and virulence genes and contribute to avoiding the possible spread of isolates with characteristics of multi-drug resistance and increased virulence, which are thought to be one of the main global challenges to public health, within our hospital.

Background/Objectives: Antimicrobial resistance represents a challenge to public health systems because of the array of resistance and virulence mechanisms that lead to treatment failure and increased mortality rates. Although for years the main driver of carbapenem resistance in Italy has been the Klebsiella pneumoniae KPC carbapenemase, recent years have seen an increase in VIM and NDM metallo-beta-lactamases (MBLs). We conducted a five-year survey of New Delhi Metallo-beta-Lactamase (NDM)-producing Klebsiella pneumoniae (NDM-Kpn) clinical isolates from the Lazio region, Italy; the study aimed to elucidate the molecular mechanisms underpinning their resistant and virulent phenotype. Methods: Antimicrobial susceptibility was evaluated by automated systems and broth microdilution. In silico analysis of acquired resistance and virulence genes was performed using whole-genome sequencing (WGS), molecular typing through MLST, and core genome multi-locus sequence typing (cgMLST). Conclusions: A total of 126 clinical NDM-Kpn isolates were collected from 19 distinct hospitals in the Lazio region. Molecular analysis highlighted the existence of NDM-1 (108/126) and NDM-5 (18/126) variants, 18 Sequence Types (STs), and 15 Cluster Types (CTs). Notably, 31/126 isolates displayed a virulence score of 4, carrying ybt, ICEKp, iuc, and rmp genes. This study identified a variety of NDM-Kpn STs, mainly carrying the bla_NDM-1 gene, with a significant number linked to high-risk clones. Of these isolates, 24.6% showed high-level resistance and virulence, emphasizing the risk of the spread of strains that combine multi-drug-resistance (MDR) and virulence. Proactive surveillance and international collaborations are needed to prevent the spread of high-risk clones, as well as further research into new antimicrobial agents to fight antibiotic resistance.

The skin microbiome is identified as one of the crucial factors in several pathological conditions, including its potential capacity in modulating cancer progression and response to treatment. A strong association of Bacilli and Betaproteobacteria classes and the Bacteroidetes phylum with melanoma is described in patients with cutaneous malignancies, while an imbalance of S. epidermidis and S. aureus is related to the progression of other skin cancers. In the present study, we characterized the microbial community in suspected lesions of 35 patients, classified, after histological analysis, as malignant melanoma lesions and benign non-melanoma lesions. Mirrored healthy skin were also included as negative control. No significant difference in alpha and beta diversity was observed when samples were categorized in four different groups (melanoma samples vs. contralateral healthy samples; melanoma samples vs. benign lesions; benign lesions vs. contralateral controls; melanoma controls vs. benign controls). The differential abundance analyses show that Corynebacterium urealyticum is more abundant in melanoma samples compared to their control, while Roseomonas gilardii is less abundant in melanoma. Staphylococcus massiliensis, Bacillus coagulans, Paracoccus yeei, Corynebacterium jeikeium, and Corynebacterium pyruviciproducens are present only in melanoma samples when compared with benign lesions.

Background/Objectives: Enterococci, particularly Enterococcus faecalis and Enterococcus faecium, are Gram-positive cocci that can cause severe infections in hospitalized patients. The rise of vancomycin-resistant enterococci (VRE) and vancomycin-variable enterococci (VVE) poses significant challenges in healthcare settings due to their resistance to multiple antibiotics. Methods: We conducted a point prevalence survey (PPS) to assess the prevalence of VRE and VVE colonization in hospitalized patients. Rectal swabs were collected from 160 patients and analyzed using molecular assays (MAs) and culture. Whole-genome sequencing (WGS) and core-genome multilocus sequence typing (cgMLST) were performed to identify the genetic diversity. Results: Of the 160 rectal swabs collected, 54 (33.7%) tested positive for the vanA and/or vanB genes. Culture-based methods identified 47 positive samples (29.3%); of these, 44 isolates were identified as E. faecium and 3 as E. faecalis. Based on the resistance profiles, 35 isolates (74.5%) were classified as VRE, while 12 (25.5%) were classified as VVE. WGS and cgMLST analyses identified seven clusters of E. faecium, with sequence type (ST) 80 being the most prevalent. Various resistance genes and virulence factors were identified, and this study also highlighted intra- and inter-ward transmission of VRE strains. Conclusions: Our findings underscore the potential for virulence and resistance of both the VRE and VVE strains, and they highlight the importance of effective infection control measures to prevent their spread. VVE in particular should be carefully monitored as they often escape detection. Integrating molecular data with clinical information will hopefully enhance our ability to predict and prevent future VRE infections.