A Preliminary Evaluation on the Antifungal Efficacy of VT-1161 against Persister Candida albicans Cells in Vulvovaginal Candidiasis.

Persister cells are a small fraction of the microbial population that survive lethal concentrations of antimicrobial agents. Candida albicans causes vaginal candidiasis, including recurrent vulvovaginal candidiasis, and may survive common antifungal treatments. The triazole VT-1161 is an antifungal agent that specifically targets fungal CYP51, as opposed to the human CYP enzyme. This work illustrates a new role of VT-1161 in eradicating the biofilm created from the persister cells of a primary biofilm of a clinical vaginal isolate of C. albicans. Antifungal activity was determined by the minimum inhibitory concentration (MIC), and the primary biofilm was treated with amphotericin B to obtain persister cells that were able to form a new biofilm. Results obtained using the new azole VT-1161 showed that VT-1161 not only eradicated a secondary biofilm formed from the persister-derived biofilm and counteracted the adhesion of C. albicans in vitro to human cells but also ameliorated C. albicans-induced infection in vivo in Galleria mellonella larvae, suggesting that it could be proposed as an alternative therapeutic strategy for the treatment of recurrent candidiasis.

Prevalence, Resistance Patterns and Biofilm Production Ability of Bacterial Uropathogens from Cases of Community-Acquired Urinary Tract Infections in South Italy.

Community-acquired urinary tract infections represent the most common infectious diseases in the community setting. Knowing the antibiotic resistance patterns of uropathogens is crucial for establishing empirical treatment. The aim of the current study is to determine the incidence of the causative agents of UTIs and their resistance profiles. Patients of all ages and both sexes were enrolled in the study, and admitted to San Ciro Diagnostic Center in Naples between January 2019 and Jun 2020. Bacterial identification and antibiotic susceptibility testing were carried out using Vitek 2 system. Among the 2741 urine samples, 1702 (62.1%) and 1309 (37.9%) were negative and positive for bacterial growth, respectively. Of 1309 patients with infection, 760 (73.1%) were females and 279 (26.9%) were males. The greatest number of positive cases were found in the in the elderly (>61 years). Regarding uropathogens, 1000 (96.2%) were Gram-negative while 39 (3.8%) were Gram-positive strains. The three most isolated pathogenic strains were Escherichia coli (72.2%), Klebsiella pneumoniae (12.4%), and Proteus mirabilis (9.0%). Strong biofilm formation ability was observed in about 30% of the tested isolates. The low resistance rates recorded against nitrofurantoin, fosfomycin, piperacillin-tazobactam, and gentamicin could suggest them as the most appropriate therapies for CA-UTIs.

Evaluation of the Pathogenic-Mixed Biofilm Formation of Pseudomonas aeruginosa/Staphylococcus aureus and Treatment with Limonene on Three Different Materials by a Dynamic Model.

BACKGROUND: Biofilms have been found growing on implantable medical devices. This can lead to persistent clinical infections. The highly antibiotic-resistant property of biofilms necessitates the search for both potent antimicrobial agents and novel antibiofilm strategies. Natural product-based anti-biofilm agents were found to be as efficient as chemically synthesized counterparts with fewer side effects. In the present study, the effects of limonene as an antibiofilm agent were evaluated on Pseudomonas aeruginosa and Staphylococcus aureus biofilm formed on different surfaces using the CDC model system in continuous flow. The flgK gene and the pilA gene expression in P. aeruginosa, and the icaA gene and eno gene in S. aureus, which could be considered as efficient resistance markers, were studied. METHODS: Mono- and dual-species biofilms were grown on polycarbonate, polypropylene, and stainless-steel coupons in a CDC biofilm reactor (Biosurface Technologies, Bozeman, MT, USA). To evaluate the ability of limonene to inhibit and eradicate biofilm, a sub-MIC concentration (10 mL/L) was tested. The gene expression of P. aeruginosa and S. aureus was detected by SYBR Green quantitative Real-Time PCR assay (Meridiana Bioline, Brisbane, Australia). RESULTS: The limonene added during the formation of biofilms at sub-MIC concentrations works very well in inhibiting biofilms on all three materials, reducing their growth by about 2 logs. Of the same order of magnitude is the ability of limonene to eradicate both mono- and polymicrobial mature biofilms on all three materials. Greater efficacy was observed in the polymicrobial biofilm on steel coupons. The expression of some genes related to the virulence of the two microorganisms was differently detected in mono- and polymicrobial biofilm. CONCLUSIONS: These data showed that the limonene treatment expressed different levels of biofilm-forming genes, especially when both types of strains alone and together grew on different surfaces. Our findings showed that limonene treatment is also very efficient when biofilm has been grown under shear stress causing significant and irreversible damage to the biofilm structure. The effectiveness of the sanitation procedures can be optimized by applying antimicrobial combinations with natural compounds (e.g., limonene).

SMFC as a tool for the removal of hydrocarbons and metals in the marine environment: a concise research update.

Marine pollution is becoming more and more serious, especially in coastal areas. Because of the sequestration and consequent accumulation of pollutants in sediments (mainly organic compounds and heavy metals), marine environment restoration cannot exempt from effective remediation of sediments themselves. It has been well proven that, after entering into the seawater, these pollutants are biotransformed into their metabolites, which may be more toxic than their parent molecules. Based on their bioavailability and toxic nature, these compounds may accumulate into the living cells of marine organisms. Pollutants bioaccumulation and biomagnification along the marine food chain lead to seafood contamination and human health hazards. Nowadays, different technologies are available for sediment remediation, such as physicochemical, biological, and bioelectrochemical processes. This paper gives an overview of the most recent techniques for marine sediment remediation while presenting sediment-based microbial fuel cells (SMFCs). We discuss the issues, the progress, and future perspectives of SMFC application to the removal of hydrocarbons and metals in the marine environment with concurrent energy production. We give an insight into the possible mechanisms leading to sediment remediation, SMFC energy balance, and future exploitation.

Allium ursinum and Allium oschaninii against Klebsiella pneumoniae and Candida albicans Mono- and Polymicrobic Biofilms in In Vitro Static and Dynamic Models.

The present study assesses the in vitro antibiofilm potential activity of extracts of wild Allium ursinum and Allium oschaninii. The active ingredients of the extracts were obtained with a technique named Naviglio (rapid solid-liquid dynamic extraction, RSLDE) which is based on an innovative and green solid-liquid extraction methodology. The extracts were tested against models of mono- and polymicrobial biofilm structures of clinically antibiotic-resistant pathogens, Klebsiella pneumoniae ATCC 10031 and Candida albicans ATCC 90028. Biofilms were studied using a static and a dynamic model (microtiter plates and a CDC reactor) on three different surfaces reproducing what happens on implantable medical devices. Antimicrobic activities were determined through minimum inhibitory concentration (MIC), while antibiofilm activity was assessed by minimum biofilm eradication concentration (MBEC) using a crystal violet (CV) biofilm assay and colony forming unit (CFU) counts. Results showed that both Allium extracts eradicated biofilms of the tested microorganisms well; biofilms on Teflon were more susceptible to extracts than those on polypropylene and polycarbonate, suggesting that when grown on a complex substrate, biofilms may be more tolerant to antibiotics. Our data provide significant advances on antibiotic susceptibility testing of biofilms grown on biologically relevant materials for future in vitro and in vivo applications.

Autotrophic and Heterotrophic Growth Conditions Modify Biomolecole Production in the Microalga Galdieria sulphuraria (Cyanidiophyceae, Rhodophyta).

Algae have multiple similarities with fungi, with both belonging to the Thallophyte, a polyphyletic group of non-mobile organisms grouped together on the basis of similar characteristics, but not sharing a common ancestor. The main difference between algae and fungi is noted in their metabolism. In fact, although algae have chlorophyll-bearing thalloids and are autotrophic organisms, fungi lack chlorophyll and are heterotrophic, not able to synthesize their own nutrients. However, our studies have shown that the extremophilic microalga Galderia sulphuraria (GS) can also grow very well in heterotrophic conditions like fungi. This study was carried out using several approaches such as scanning electron microscope (SEM), gas chromatography/mass spectrometry (GC/MS), and infrared spectrophotometry (ATR-FTIR). Results showed that the GS, strain ACUF 064, cultured in autotrophic (AGS) and heterotrophic (HGS) conditions, produced different biomolecules. In particular, when grown in HGS, the algae (i) was 30% larger, with an increase in carbon mass that was 20% greater than AGS; (ii) produced higher quantities of stearic acid, oleic acid, monounsaturated fatty acids (MUFAs), and ergosterol; (iii) produced lower quantities of fatty acid methyl esters (FAMEs) such as methyl palmytate, and methyl linoleate, saturated fatty acids (SFAs), and poyliunsaturated fatty acids (PUFAs). ATR-FTIR and principal component analysis (PCA) statistical analysis confirmed that the macromolecular content of HGS was significantly different from AGS. The ability to produce different macromolecules by changing the trophic conditions may represent an interesting strategy to induce microalgae to produce different biomolecules that can find applications in several fields such as food, feed, nutraceutical, or energy production.