Urinary tract infections (UTIs) and catheter-associated UTIs (CAUTIs) are the principal hospital-acquired infections. Proteus mirabilis is characterized by several virulence factors able to promote adhesion and biofilm formation and ameliorate the colonization of urinary tract and the formation of crystalline biofilms on the abiotic surface of the urinary catheters. Since, to date, the role of P. mirabilis in the etiopathogenesis of different types of urinary tract infections is not well established, in this study we sought to characterize two different clinically isolated strains of P. mirabilis (PM1 and PM2) with distinctive phenotypes and analyzed various virulence factors possibly implicated in the ability to induce UTIs and CAUTIs. In particular, we analyzed motility, biofilm formation both on abiotic and biotic surfaces of PM1 and PM2 and paralleled these parameters with the ability to induce an inflammatory response in an epithelial cell model. Results showed that PM1 displayed major motility and a capacity to form biofilm and was associated with an anti-inflammatory response of host cells. Conversely, PM2 exhibited lack motility and a had slower organization in biofilm but promoted an increase of proinflammatory cytokine expression in infected epithelial cells. Our study provides data useful to start uncovering the pathologic basis of P. mirabilis-associated urinary infections. The evidence of different virulence factors expressed by PM1 and PM2 highlights the possibility to use precise and personalized therapies targeting specific virulence pathways.

Background: The integrity of the intestinal barrier is fundamental to gut health and homeostasis; its damage can increase intestinal permeability, with translocation of bacteria and/or endotoxins from gut, and the onset of various intestinal diseases. Lactobacillus spp. is one of the most common probiotics normally found in fermented foods and dairy products and is known for its anti-inflammatory and immunomodulatory properties and for its ability to protect and enhance the intestinal barrier functions. The aim of this work was to evaluate the ability of different strains of Lactobacillus spp. to improve in vitro the integrity of the intestinal barrier, to exert anti-inflammatory and immunomodulatory activity and to prevent Salmonella Typhimurium and enteroinvasive Escherichia coli (EIEC) infections. Methods: We analyzed the cellular expression of tight junctions, antimicrobial peptide HBD-2, pro-inflammatory cytokines and the inhibition of pathogens adhesion and invasion in a model of co-cultured epithelial cells treated with Lactobacillus spp. Results: L. brevis, L. reuteri and L. rhamnosus proved to be more effective in protecting the intestinal epithelium. Conclusions: These in vitro studies can help select strains particularly active in their intended use to obtain consortia formulations that can have as much maximum yield as possible in terms of patient benefit.

Background: The intestinal microbiota is a very active microbial community interacting with the host in maintaining homeostasis; it acts in cooperation with intestinal epithelial cells, which protect the host from the external environment by producing a diverse arsenal of antimicrobial peptides (AMPs), including β-defensins-2 and 3 (HBD-2 and HBD-3), considered among the most studied in this category. However, there are some circumstances in which an alteration of this eubiotic state occurs, with the triggering of dysbiosis. In this condition, the microbiota loses its protective power, leading to the onset of opportunistic infections. In this scenario, the emergence of multi-drug resistant biofilms from Pseudomonas aeruginosa and Staphylococcus aureus is very frequent. Methods: We created a Caco-2 intestinal epithelial cell line stably transfected with the genes, encoding HBD-2 and HBD-3, in order to evaluate their ability to inhibit the intestinal biofilm formation of P. aeruginosa and S. aureus. Results: Both HBD-2 and HBD-3 showed anti-biofilm activity against P. aeruginosa and S. aureus. Conclusions: The exploitation of endogenous antimicrobial peptides as a new anti-biofilm therapy, in isolation or in combination with conventional antibiotics, can be an interesting prospect in the treatment of chronic and multi-drug resistant infections.

Oral candidiasis (OC) is an opportunistic fungal infection of the oral mucosae, sustained by Candida albicans or other non-albican Candida species (NAC), usually eradicated by conventional antifungals of the classes of azoles, polyenes, or derivative from echinocandins. OC usually occurs under predisposing local or systemic factors. C. lusitaniae is an opportunistic strain that is rarely responsible for human infection and occurs mainly in severe immunocompromised states. The present work reported an unconventional case of OC in an otherwise healthy immunocompetent woman sustained by C. lusitaniae and a multi-resistant strain of C. albicans.

The skin serves as the first barrier against pathogen attacks, thanks to its multifunctional microbial community. Malassezia furfur is a commensal organism of normal cutaneous microflora but is also a cause of skin diseases. It acts on different cell pattern recognition receptors (TLRs, AhR, NLRP3 inflammasome) leading to cellular damage, barrier impairment, and inflammatory cytokines production. Lactobacillus spp. Is an endogenous inhabitant of healthy skin, and studies have proven its beneficial role in wound healing, skin inflammation, and protection against pathogen infections. The aim of our study is to demonstrate the ability of live Lactiplantibacillus plantarum to interfere with the harmful effects of the yeast on human keratinocytes (HaCat) in vitro. To enable this, the cells were treated with M. furfur, either alone or in the presence of L. plantarum. To study the inflammasome activation, cells require a stimulus triggering inflammation (LPS) before M. furfur infection, with or without L. plantarum. L. plantarum effectively counteracts all the harmful strategies of yeast, reducing the phospholipase activity, accelerating wound repair, restoring barrier integrity, reducing AhR and NLRP3 inflammasome activation, and, consequently, releasing inflammatory cytokines. Although lactobacilli have a long history of use in fermented foods, it can be speculated that they can also have health-promoting activities when topically applied.

Staphylococci, including Staphylococcus aureus and Staphylococcus epidermidis, are important human pathogens associated with potentially life-threatening infections. Their great biofilm-producing ability and the development of resistance mechanisms often account for therapeutic failure. Hence, the scientific community has devoted intensive efforts to the development of antimicrobial compounds active against both planktonic and sessile bacterial populations. Contextually, antimicrobial peptides (AMPs) are natural peptides produced by the innate immunity of every organism, representing a potential new therapeutic solution against human microbial pathogens. Our work focused on the in vitro activity of Oreoch-1, an AMP from the gills of Nile tilapia (Oreochromis niloticus), against standard and clinical S. aureus and S. epidermidis strains. Firstly, the cytotoxicity profile of Oreoch-1 was determined in human colon carcinoma cells. Secondly, its antibacterial spectrum was explored against staphylococcal strains to set up the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). Our results highlighted an antibacterial activity in the range 6.25–25 μM, with a general bacteriostatic effect. Therefore, the biofilm-inhibitory property was assessed against S. aureus ATCC 25923 and S. epidermidis ATCC 35984, indicating a significant reduction in S. aureus biomass at sub-MIC concentrations. Overall, our study indicates Oreoch-1 as a promising new therapeutic weapon against staphylococcal infections.