AIMS:The rising wave of antimicrobial resistant organisms, together with the lack of novel group of antibacterial agents, represents a major concern in modern medicine. This study aims to investigate the anti-staphylococcal potential of two semi-synthetic derivatives of naturally occurring nitrogen-containing molecules [2-O-(3-methoxybenzoyl)-3-O-methylpancracine (1 nm) and 2-O-(3,5-dimethoxybenzoyl)-3-O-methylpancracine (2 nm)]. METHODS AND RESULTS:The two semi-synthetic analogues were evaluated against reference bacterial strains and clinical bacterial isolates. Furthermore, the most active compound, 1 nm, was subjected to synergistic activity screening with the commercial antibiotics against MRSA. The toxicity profile of 1 nm was further explored using in vitro (HepG2 and HK-2 cells) and in vivo (Galleria mellonella) models, accompanied by an insight into its in silico physicochemical characteristics and cytotoxicity. Our results suggest that this derivative possesses promising activity against clinically relevant staphylococci, while showing a favourable safety and bioavailability profile. In addition, this compound showed synergistic or additive effects in combination with several clinically important antibiotics. CONCLUSIONS:1 nm demonstrates promising adjuvant anti-staphylococcal activity, with a favourable safety profile and an additive interaction with the last-resort antibiotic linezolid, supporting its potential to mitigate resistance development within combination strategies.

This comprehensive study provides insight into the antibacterial action of a recently published 2-chloro-N-(oxazol-2-yl)isonicotinamide (AB15), intending to assess its potential as a candidate adjuvant molecule to support existing antibacterial drugs. Within the determination of the antibacterial effect, a promising activity against a member of the ESKAPE group with reduced treatment options, biofilm producer, Acinetobacter baumannii, was recognized (MIC of AB15 ranged from 15.63 to 62.5 µM). In addition, AB15 exhibited bactericidal activity and non/low-toxicity in vitro (IC50 > 1000 µM using HK-2 cells) and in vivo (LD50 > 500 mg/kg of body weight of the Galleria mellonella larvae, for both intra-hemocoel and per oral administration routes). Checkerboard assay revealed additive and synergistic interactions of AB15 and last-resort antibiotic drug, colistin (CST). Moreover, attention was also given to a frequently overlooked antibiofilm activity — the ability to suppress bacterial dissemination from microbial biofilms, and parameter MBDC (minimum biofilm dissemination concentration) was introduced. The study of the antibiofilm activity of AB15 and CST, both acting individually, or in AB15 + CST combination, revealed that AB15 has significant potential to suppress bacterial dissemination from biofilm formed by a clinical isolate Acinetobacter baumannii and that it contributes to this effect when combined with CST. Finally, AB15 + CST combination demonstrated significantly greater biocompatibility towards human erythrocytes than CST acting individually at an equivalent antibiofilm-effective concentration. The role of AB15 as a promising adjuvant molecule to CST is also supported by its distinct mechanism of action, which reduces the risk of antimicrobial resistance emergence. To conclude, AB15 exhibits several essential attributes that support its designation as a promising antibiotic adjuvant.

Background: Increasing rates of acquired resistance have justified the critical need for novel antimicrobial drugs. One viable concept is the modification of known drugs. Methods & results: 21 mafenide-based compounds were prepared via condensation reactions and screened for antimicrobial efficacy, which demonstrated promising activity against both Gram-positive and Gram-negative pathogens, pathogenic fungi and mycobacterial strains (minimum inhibitory concentrations from 3.91 μM). Importantly, they retained activity against a panel of superbugs (methicillin- and vancomycin-resistant staphylococci, enterococci, multidrug-resistant Mycobacterium tuberculosis) without any cross-resistance. Unlike mafenide, most of its imines were bactericidal. Toxicity to HepG2 cells was also investigated. Conclusion: Schiff bases were significantly more active than the parent drug, with iodinated salicylidene and 5-nitrofuran/thiophene-methylidene scaffolds being preferred in identifying the most promising drug candidates.

Antibiotic resistance is among the largest threats to global health, with a potentially serious socioeconomic impact. One of the strategies to deal with the predicted catastrophic future scenarios associated with the rapid emergence of resistant infectious agents lies in the discovery and research of new anti-infectives.

The greatest threat and medicinal impact within gram-positive pathogens are posed by two bacterial genera, Staphylococcus and Enterococcus. Chalcones have a wide range of biological activities and are recognized as effective templates in medicinal chemistry. This study provides comprehensive insight into the anti-staphylococcal and anti-enterococcal activities of two recently published brominated and chlorinated pyrazine-based chalcones, CH-0y and CH-0w. Their effects against 4 reference and 12 staphylococcal and enterococcal clinical isolates were evaluated. Bactericidal action, the activity in combination with selected conventional antibiotics, the study of post-antimicrobial effect (PAE, PAE/SME), and in vitro and in vivo toxicity, were included. In CH-0y, anti-staphylococcal activity ranging from MIC = 15.625 to 62.5 μM, and activity against E. faecium from 31.25 to 62.5 μM was determined. In CH-0w, anti-staphylococcal activity ranging from 31.25 to 125 μM, and activity against E. faecium and E. faecalis (62.5 μM) was revealed. Both CH-0y and CH-0w showed bactericidal action, beneficial impact on bacterial growth delay within PAE and PAE/SME studies, and non/low toxicity in vivo. Compared to CH-0w, CH-0y seems to have higher anti-staphylococcal and less toxic potential. In conclusion, chalcones CH-0y and CH-0w could be considered as structural pattern for future adjuvants to selected antibiotic drugs.

The yeasts of the genus Candida are among the most clinically significant fungal pathogenic agents. One of the unique features of the Candida species’ pathogenicity is their ability to form biofilms. Generally, infections caused by biofilm-forming microorganisms tend to have chronic course and are difficult to treat. This fact highlights the need to search for drugs with anti-biofilm activities. At present, there are variety of protocols for performing antifungal anti-biofilm activity testing in which fundamental differences, especially in the choice of cultivation media for biofilm formation, can be noted. In our study, we focused on the effect of four different culture media on biofilm biomass formation in ten Candida spp. strains. With emphasis placed on clinical significance, strains of the C. albicans species were predominantly included in this study. Based on our results, we can conclude that the availability of other components in the culture media, such as amino acids or proteins, and not just the commonly mentioned glucose availability, helps promote the transition of Candida yeasts into a sessile form and leads to in vitro robust biofilm formation. We revealed that biofilm formation in C. albicans strains was enhanced, especially in media supplemented with fetal bovine serum (FBS). The nutritionally balanced cultivation medium with 10 g/L glucose and 10% (v/v) FBS evidently showed the most significant benefit for in vitro biofilm production in C. albicans strains.

One of the pathways for the delivery of virulence effector molecules into the extracellular environment of Candida albicans relies on the release of membrane-bound carriers which are called extracellular vesicles (EVs). Only a few studies aimed at investigating Candida albicans extracellular vesicles protein cargo and its potential contribution to the pathogenesis of C. albicans infections have been conducted to date. In this study, we mainly focused on a search for proteins with a demonstrated linkage to pathogenesis in EVs isolated from two C. albicans strains, the model strain ATCC 90028 and the clinical isolate from a woman suffering from vulvovaginal candidiasis. For the purpose of mimicking one of many hostile conditions during a host-pathogen interaction, C. albicans strains in a nutrient-limited medium were cultivated. We have hypothesized that this unfavourable, stressful condition could contribute to the induction of virulence effector molecules being released at a more extensive rate. In conclusion, 34 proteins with an undisputed linkage to C. albicans pathogenesis were detected in the extracellular vesicle cargoes of both strains. In case of the clinical isolate strain, no unique virulence-associated proteins were detected. In the C. albicans ATCC 90028 model strain, three unique proteins were detected, namely: agglutinin-like protein 3 (Als3), secreted aspartic protease 8 (Sap8) and cell surface superoxide dismutase [Cu-Zn] 6 (Sod6).

Two novel thiosemicarbazones and eight novel 2-{[1-(5-alkyl/arylalkylpyrazin-2-yl)ethylidene]hydrazono}-1,3-thiazolidin-4-ones were prepared and tested against a panel of eight fungal strains–Candida albicans ATCC 44859, Candida tropicalis 156, Candida krusei E 28, Candida glabrata 20/I, Trichosporon asahii 1188, Aspergillus fumigatus 231, Lichtheimia corymbifera 272, and Trichophyton interdigitale 445. 1,3-Thiazolidin-4-ones exhibited activity against all strains, the most potent derivative was 2-{[1-(5-butylpyrazin-2-yl)ethylidene]hydrazono}e-1,3-thiazolidin-4-one. Susceptibility of C. glabrata to the studied 1,3-thiazolidin-4-ones (minimum inhibitory concentrations (MICs) were in the range 0.57 to 2.78 mg/L) is of great interest as this opportunistic pathogen is poorly susceptible to azoles and becomes resistant to echinocandins. Antifungal potency of thiosemicarbazones was slightly lower than that of 1,3-thiazolidin-4-ones.

Herein, we report the discovery and structure-activity relationships of 5-substituted-2-[(3,5-dinitrobenzyl)sulfanyl]-1,3,4-oxadiazoles and 1,3,4-thiadiazoles as a new class of antituberculosis agents. The majority of these compounds exhibited outstanding in vitro activity against Mycobacterium tuberculosis CNCTC My 331/88 and six multidrug-resistant clinically isolated strains of M. tuberculosis, with minimum inhibitory concentration values as low as 0.03 μM (0.011-0.026 μg/mL). The investigated compounds had a highly selective antimycobacterial effect because they showed no activity against the other bacteria or fungi tested in this study. Furthermore, the investigated compounds exhibited low in vitro toxicities in four proliferating mammalian cell lines and in isolated primary human hepatocytes. Several in vitro genotoxicity assays indicated that the selected compounds have no mutagenic activity. The oxadiazole and thiadiazole derivatives with the most favorable activity/toxicity profiles also showed potency comparable to that of rifampicin against the nonreplicating streptomycin-starved M. tuberculosis 18b-Lux strain, and therefore, these derivatives, are of particular interest.

Chalcones, i.e., compounds with the chemical pattern of 1,3-diphenylprop-2-en-1-ones, exert a wide range of bio-activities, e.g., antioxidant, anti-inflammatory, anticancer, anti-infective etc. Our research group has been focused on pyrazine analogues of chalcones; several series have been synthesized and tested in vitro on antifungal and antimycobacterial activity. The highest potency was exhibited by derivatives with electron withdrawing groups (EWG) in positions 2 and 4 of the ring B. As halogens also have electron withdrawing properties, novel halogenated derivatives were prepared by Claisen-Schmidt condensation. All compounds were submitted for evaluation of their antifungal and antibacterial activity, including their antimycobacterial effect. In the antifungal assay against eight strains of selected fungi, growth inhibition of Candida glabrata and Trichophyton interdigitale (formerly T. mentagrophytes) was shown by non-alkylated derivatives with 2-bromo or 2-chloro substitution. In the panel of selected bacteria, 2-chloro derivatives showed the highest inhibitory effect on Staphylococcus sp. In addition, all products were also screened for their antimycobacterial activity against Mycobacterium tuberculosis H37RV My 331/88, M. kansasii My 235/80, M. avium 152/80 and M. smegmatis CCM 4622. Some of the examined compounds, inhibited growth of M. kansasii and M. smegmatis with minimum inhibitory concentrations (MICs) comparable with those of isoniazid.

Infectious diseases, such as tuberculosis and invasive mycoses, represent serious health problems. As a part of our long-term efforts to find new agents for the treatment of these diseases, a new series of pyrazine analogs of chalcones bearing an isopropyl group in position 5 of the pyrazine ring was prepared. The structures of the compounds were corroborated by IR and NMR spectroscopy and their purity confirmed by elemental analysis. The susceptibility of eight fungal strains to the studied compounds was tested. The results have been compared with the activity of some previously reported propyl derivatives. The only strain that was susceptible to the studied compounds was Trichophyton mentagrophytes. It was found that replacing a non-branched propyl with a branched isopropyl did not have a decisive and unequivocal influence on the in vitro antifungal activity against T. mentagrophytes. In vitro activity against Trichophyton mentagrophytes comparable with that of fluconazole was exhibited by nitro-substituted derivatives. Unfortunately, no compound exhibited efficacy comparable with that of terbinafine, which is the most widely used agent for treating mycoses caused by dermatophytes. Some of the prepared compounds were assayed for antimycobacterial activity against M. tuberculosis H37Rv. The highest potency was also displayed by nitro-substituted compounds. The results of the present study are in a good agreement with our previous findings and confirm the positive influence of electron-withdrawing groups on the B-ring of chalcones on the antifungal and antimycobacterial activity of these compounds.

Tetrazole derivatives containing nitro substituents have been identified as promising antitubercular agents.

Substitution of chlorine in 5-chloro-N-phenylpyrazine-2-carboxamide (1) with simple n-alkylamines yielded a series of 5-alkylamino-N-phenylpyrazine-2-carboxamides (propylamino to octylamino derivatives), which possessed similar or increased activity against Mycobacterium tuberculosis H37Rv compared to parent 5-chloro derivative (1), with MIC ranging from 2.5 to 12.2μM. 5-Butylamino to 5-heptylamino derivatives exerted similar activity also against Mycobacterium kansasii. Importantly, the substitution led also to significant decrease of in vitro cytotoxicity in HepG2 cell line. 5-Heptylamino-N-phenylpyrazine-2-carboxamide (1e) exerted MIC=2.5μM (M.tbc) and IC50 >250μM (HepG2). Further modification of alkylamino chain with terminal methoxy or hydroxy group lead to compounds with decreased or none activity, the decrease was proportional to the decrease of lipophilicity. 5-(2-Phenylethylamino) and 5-(3-phenylpropylamino) derivatives were also of decreased activity. On contrary to alkylamino derivatives derived from 1, alkylamino derivatives derived from 5-chloro-N-2-chlorophenylpyrazine-2-carboxamide (2) possessed substantially decreased or none activity. None of the prepared compounds was active against Mycobacterium avium.

Case of 59-year-old male with chronic obstructive pulmonary disease and a number of comorbidities, who has developed meningoencephalitis caused by Cryptococcus neoformans var. grubii with polyarteritis nodosa diagnosed during hospitalization, was presented. Before evidence of meningoencephalitis, the patient was being treated with ketoconazole and low doses of fluconazole (200 mg/day) for alleged candidiasis. The dosage was increased (800 mg/day) following laboratory diagnosis of C. neoformans based on positive latex agglutination test and biochemical identification of encapsulated yeast isolated from the blood and CSF. Later, the yeast identification was confirmed by sequencing analysis. Owing to inadequate clinical response, fluconazole therapy was switched to voriconazole (400 mg/day) and later to intravenous amphotericin B (1.0 mg/kg per day). Despite of a temporary stabilization and improvement, which correlated with decline of cryptococcal antigen titers (from 1:1024 to 1:8), after 6 weeks, the patient's underlying condition deteriorated due to severe pancolitis and serious nosocomial bacterial infections. The patient died of multiorgan failure several days later. Our case demonstrates a possible connection between the development of life-threatening cryptococcosis and an autoimmune vasculitis disease and emphasizes that the outcome of the management of cryptococcal meningoencephalitis is highly dependent on early diagnosis, adequate treatment, including dosage, and last but not least control of underlying disease and risk factors.

In this work, a new class of highly potent antituberculosis agents, 1-substituted-5-[(3,5-dinitrobenzyl) sulfany1]-1H-tetrazoles and their oxa and selanyl analogs, is described. The minimal inhibitory concentration (MIC) values reached I mu M (0.36-0.44 mu g/mL) against Mycobacterium tuberculosis CNCTC My 331/88 and 0.25-1 mu M against six multidrug-resistant clinically isolated strains of M. tuberculosis. The antimycobacterial effects of these compounds were highly specific because they were ineffective against all eight bacterial strains and eight fungal strains studied. Furthermore, these compounds exhibited low in vitro toxicity in four mammalian cell lines (IC50 > 30 mu M). We also examined the structure-activity relationships of the compounds, particularly the effects on antimycobacterial activity of the number and position of the nitro groups, the linker between tetrazole and benzyl moieties, and the tetrazole itself. Relatively high variability of substituent R-1 on the tetrazole in the absence of negative effects on anti-mycobacterial activity allows further structural optimization with respect to toxicity and the ADME properties of the 1-substituted-5-[(3,5-dinitrobenzyl)sulfanyl]-1H-tetrazoles lead compounds. (C) 2014 Elsevier Masson SAS. All rights reserved.

Quaternary ammonium salts substituted with a long alkyl chain exemplify a trustworthy group of medicinal compounds frequently employed as antifungal and antibacterial agents. A great asset of these surfactants underlying their widespread use is low local and system toxicity in humans. In this Letter, a series of novel quaternary 6-hydroxyquinolinium salts with varying length of N-alkyl chain (from C10 to C18) was synthesized and tested for in vitro activity against pathogenic bacterial and fungal strains. 6-Hydroxyquinolinium salt with C12 alkyl chain seems to be very interesting candidate due to a high antimicrobial efficacy and cytotoxic safety.

Outbreak of exogenous Fusarium endophthalmitis after cataract surgery was evaluated. Twenty patients developed postoperative endophthalmitis. In 19 eyes, pars plana vitrectomy (PPV) was performed, in 14 cases (74 %) with primary intraocular lens explantation. In one case, the PPV was not performed because of poor general condition of the patient. Symptoms of endophthalmitis (damaged vision, iritis, tyndallization in anterior chamber, hypopyon) occurred at intervals of 16-79 days (mean 31.3 days). Fungal etiology was documented in 12 eyes (60 %). Fusarium oxysporum was evidenced by culture and/or microscopy and confirmed by PCR and sequencing analysis. Eighteen (90 %) patients were treated with oral voriconazole (400 mg/day) for a period of 4-6 weeks. The final visual acuity was 6/15 in 1 case (5 %), 6/60 and worse in 17 eyes (85 %), and in 2 cases (10 %), enucleation had to be performed. Viscoelastic filling material was suggested the most likely source of infection. Endophthalmitis caused by Fusarium spp. are a potentially big threat for patients with serious impact on vision. Successful management of the infection is highly dependent on early diagnosis including species identification and antifungal susceptibility testing, and on aggressive and long-term treatment.

A new strategy for the synthesis of trans-and cis + trans-3,4,5-trisubstituted isoxazolines from allyl compounds of QCH(2)CH=CH2 type (Q = PhO, 2,2'-bithiophen-5-yl, BuO, Me3CS, PhN(COMe) and others) has been developed. The dipolarophiles are prepared via: a) Ru-carbene catalysed metathesis of Qallyl; b) catalytic isomerization followed by Ru-carbene mediated metathesis; c) Ru-carbene catalysed metathesis followed by isomerization. 1,3-dipolar cycloaddition of nitrile oxide to dipolarophiles obtained via route a), b) or c), including high pressure activated reactions leads to 3,4,5-trisubstituted isoxazolines. Quantitative E-stereoselective homometathesis of some QCH(2)CH=CH2 to (E)-QCH(2)CH=CHCH(2)Q and new highly effective ruthenium and basic catalytic systems for the isomerization of allyl compounds have also been presented. Moreover, easily available (Z)-XCH2CH=CHCH2X allyl compounds were used for the synthesis of cis-3,4,5-trisubstituted isoxazolines. It has been proved by in vitro tests that some of the isoxazolines show interesting antifungal activity comparable to that of fluconazole.

OBJECTIVE:To analyze experimental and clinical data on diabetes mellitus (DM) related to infections with focus on vaginal mycosis. To evaluate a role of DM in the epidemiology of vulvovaginal candidiasis.DESIGN:Review.SETTING:Department of Clinical Microbiology, Department of Biological and Medical Sciences, Faculty of Pharmacy, Department of Obstetrics and Gynecology, Charles University in Prague, Faculty of Medicine and University Hospital Hradec Kralove.METHODS:Review of literature data.RESULTS:DM is a risk factor for fungal infections caused by yeasts (Candida albicans), members of Mucorales fungi, some dimorphic fungi (Coccidioides) and agents of onychomycosis. DM is usually associated only with increased colonization of the anatomical sites (oral cavity, vagina), and/ or with an intensified symptomatology of infection (onychomycosis, mucormycosis). Diabetic patients with oropharyngeal and vulvovaginal candidiasis have frequently changed etiology spectrum. The patients with VVC and DM, especially of older age or with prone to relapses, have tendency to shift of the spectrum to non-albicans species, mainly C. glabrata. Treatment of VVC in diabetic patients can be complicated owing to unfavourable antifungal susceptibility profile (C. glabrata) and/ or adverse interactions between some azole antifungals and sulfonylurea-based antidiabetics.CONCLUSION:Diabetes mellitus is often cited as a risk factor, although in many cases there is a lack of reliable and clinically relevant information. This does not mean that this disease can be underestimated. On the contrary, it is necessary to get the DM as soon as possible under control and thus prevent complications when infection develops. Individual approach should be applied to the diabetic patients at risk of an infection. Yeast colonization and development of vaginal infection is complex process primarily dependent on sexual hormones, indigenous microbiota and finely tuned mechanisms of local immunity. Role of DM consists in the fact that it is one of the important co-factors that can change the setup of the vaginal environment in favour of yeasts and thus promote or facilitate the development of VVC.

In this study, a series of N-substituted 2-aminobenzothiazoles was prepared according to a recently developed method. Twelve compounds were tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Primary in vitro screening of the discussed compounds was also performed against fungal, bacterial and mycobacterial species. The biological activities of some compounds were comparable or higher than the standards phenoxymethylpenicillin or pyrazinamide. The most effective compounds demonstrated insignificant toxicity against the human monocytic leukemia THP-1 cell line. For all compounds, the structure-activity relationships are discussed.