Exploring the antibiofilm efficacy of cinnamaldehyde against Malassezia globosa associated pityriasis versicolor.

BACKGROUND: Malassezia globosa is a commensal basidiomycetous yeast occurring on the skin that causes pityriasis versicolor (PV) and seborrheic dermatitis, but that has also been implicated in other dermatoses. Cinnamaldehyde (CM) has antibacterial, antioxidant, and anti-inflammatory activities, but the effect of CM on M. globosa-infected PV has not been clarified. PURPOSE: The study aimed to investigate the possible antifungal and antibiofilm activities of CM against M. globosa-infected PV in vivo and in vitro. METHODS: The broth microdilution method was used to determine the minimum inhibitory concentration (MIC) of CM against M. globosa. The crystal violet staining assay and XTT assay were used to investigate the inhibition of CM on biofilm formation and the eradication of mature biofilms. The visualizations of the biofilm and cell distribution in the biofilm matrix were performed with a scanning electron microscope and confocal laser scanning microscope. The kits of antioxidant kinase were used to determine the activities of oxidative stress markers in M. globosa-stimulated HaCaT cells. Western blot assays were used to evaluate the role of TLR2/NF-κB in vitro. Furthermore, the protective effect of CM was assessed in M. globosa-associated PV mice. The expressions of inflammatory cytokines and apoptosis were screened using ELISA assays. The expressions of interleukin-6 and tumor necrosis factor-α were measured by an immunohistochemistry method in vivo. RESULTS: Our results showed that the MIC of CM against planktonic cells of M. globosa was 4 µg/ml and treatment with 20 × MIC CM eradicated mature biofilms of M. globosa. In vitro, after CM treatment the levels of oxidative stress indicators (i.e., superoxide dismutase, catalase, glutathione) significantly increased, while the levels of malondialdehyde decreased. In addition, the expression of TLR2/NF-κB in HaCaT cells was significantly reduced after CM treatment. On the other hand, an in vivo therapeutic effect of CM was assessed against M. globosa-infected mice. The fungal load on the skin decreased after treatment with CM compared to the M. globosa-infected group. In addition, the uninfected animals showed a normal skin structure, whereas, the M. globosa-infected mice showed extensive infiltration of neutrophils in skin tissues that improved after treatment with CM. Meanwhile, the levels of inflammatory and apoptotic factors improved after CM treatment. CONCLUSION: Our results showed that CM inhibits the biofilm formation of M. globosa and eradicates mature biofilms of M. globosa. Treatment with CM significantly decreased oxidative stress, apoptosis, and inflammatory markers in the skin tissue and HaCaT cells. Hence, this study suggests that CM is a good candidate therapeutic agent against M. globosa-induced PV infections because of its antifungal, antibiofilm, and anti-inflammatory properties.

A pilot study of antimicrobial effects and ototoxicity of a Norway spruce (Picea abies) resin-based canine otic rinse product.

BACKGROUND: Norway spruce (Picea abies) resin-based products are used in human medicine. A resin-based otic rinse also could be useful in supportive care of canine otitis externa (COE), yet information on its antimicrobial effect against canine pathogens or ototoxicity is lacking. OBJECTIVES: To investigate the antimicrobial properties and ototoxicity of a commercial resin-based otic product. MATERIALS AND METHODS: Antimicrobial effect was evaluated using a standardised challenge test on Staphylococcus pseudintermedius, Corynebacterium auriscanis, Pseudomonas aeruginosa, Escherichia coli, Malassezia pachydermatis, and Streptococcus halichoeri strains to measure reduction in growth after 24 h exposure to the product. Effect on cell morphology was investigated by exposing S. pseudintermedius, C. auriscanis, P. aeruginosa and M. pachydermatis to the product in 20% and 100% (v/v) concentrations for 6, 24 and 48 h, and evaluating cells by transmission (TEM) and scanning (SEM) electron microscopy. An in vitro microbial kill-rate assay also was performed. Auditory brain stem response test, clinical evaluation and postmortem histological evaluation of ear canals were undertaken on experimental guinea pigs treated with the test product or saline controls. RESULTS: The product showed >log 5 growth reduction for all strains in the challenge test. TEM and SEM images showed clear changes in the cells' inner structures and deterioration of cells, and 100% (v/v) test product exposure induced microbial killing in 1-2 h. Ototoxicity was not detected in guinea pigs. CONCLUSIONS AND CLINICAL RELEVANCE: The product may be an option in supportive care of COE because of antimicrobial effects and lack of ototoxic properties in a guinea pig model.

Identification of components in Kazakhstan honeys that correlate with antimicrobial activity against wound and skin infecting microorganisms.

BACKGROUND: Antimicrobial drug resistance is a major public health threat that can render infections including wound and skin infections untreatable. The discovery of new antimicrobials is critical. Approaches to discover novel antimicrobial therapies have included investigating the antimicrobial activity of natural sources such as honey. In this study, the anti-microbial activity and chemical composition of 12 honeys from Kazakhstan and medical grade manuka honey were investigated. METHODS: Agar well diffusion and broth culture assays were used to determine anti-microbial activity against a range of skin and wound infecting micro-organisms. Folin-Ciocalteu method was used to determine the total phenol content of the honeys and non-targeted liquid chromatography analysis was performed to identify components that correlated with antimicrobial activity. RESULTS: In the well diffusion assay, the most susceptible micro-organisms were a clinical isolate of Methicillin resistant Staphylococcus aureus (MRSA) and Enterococcus faecalis (ATCC 19433). Buckwheat & multi-floral honey from Kazakhstan demonstrated the highest antimicrobial activity against these two micro-organisms. Kazakhstan honeys with a buckwheat floral source, and manuka honey had the highest total phenol content. Non-targeted liquid chromatography analysis identified components that correlated with anti-microbial activity as hydroxyphenyl acetic acid, p-coumaric acid, (1H)-quinolinone, and abscisic acid. CONCLUSIONS: The Kazakhstan honeys selected in this study demonstrated antimicrobial activity against wound and skin infecting micro-organisms. Compounds identified as correlating with antimicrobial activity could be considered as potential bioactive agents for the treatment of wound and skin infections.

Prevalence and in vitro antifungal susceptibility of commensal yeasts in the external ear canal of cats.

BACKGROUND: Lifestyle factors such as hair length, the frequency of ear cleaning and bathing, age, cat rearing, and sex may contribute to opportunistic yeast infections in the external ear canal of cats. This study aimed to determine the prevalence of commensal yeast organisms in cats' external ear canals, evaluate their predisposing lifestyle factors, and test the susceptibility of Malassezia pachydermatis to antifungal agents. RESULTS: A total of 53 cats (33 male and 20 female) seronegative for feline leukemia virus and feline immunodeficiency virus were enrolled in this study. Their mean age (± standard deviation) was 6.04 (± 3.49) years. Fungal cultures and polymerase chain reaction tests were performed to identify the yeast species derived from the external ear canal. The association between lifestyle factors and the presence of M. pachydermatis was evaluated using Fisher's exact test. The susceptibility of M. pachydermatis to antifungal agents was also analyzed. M. pachydermatis was the most frequently recovered yeast species, with a prevalence of 50.94 % (95 % confidence interval [CI]: 36.84-64.94 %). There was an association between hair length and a positive culture for M. pachydermatis (p = 0.0001). The odds of a negative culture for M. pachydermatis among short-haired cats was 11.67 (95 % CI, 3.22-42.24) times higher than that among long-haired cats (p = 0.0002). There was also an association between the frequency of ear cleaning and the presence of M. pachydermatis (p = 0.007). The odds of a negative culture for M. pachydermatis in cats that were receiving ear cleaning at intervals of ≤ 2 weeks was 5.78 (95 % CI, 1.67-19.94) times greater than that of cats receiving ear cleaning at intervals greater than 2 weeks or never (p = 0.0055). Ranges of minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations for itraconazole, ketoconazole, miconazole, and terbinafine against M. pachydermatis were ≤ 0.063-4 and ≤ 0.063-≥32, ≤ 0.063-8 and 0.125-≥32, ≤ 0.063-≥32 and 0.5-≥32, and ≤ 0.016-1 and 0.125-8 µg/ml, respectively. CONCLUSIONS: M. pachydermatis was the most commonly identified yeast organism in the external ear canal of healthy cats. Hair length and the frequency of ear cleaning played a role in the colonization of M. pachydermatis. The M. pachydermatis isolates had various MIC levels for common fungicides.

First dinuclear rhodium(II) complexes with triazolopyrimidines and the prospect of their potential biological use.

Five novel rhodium(II) complexes of general formula [Rh2(µ-OOCCH3)4L2], where L is a triazolopyrimidine derivative, in particular dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) for (1), 5,7-diethyl-1,2,4-triazolo[1,5-a]pyrimidine (detp) for (2), 7-isobutyl-5-methyl-1,2,4-triazolo[1,5-a]pyrimidine (ibmtp) for (3), 7-hydroxy-5-methyl-1,2,4-triazolo[1,5-a]pyrimidine (HmtpO) for (4) and 5,7-ditertbutyl-1,2,4-triazolo[1,5-a]pyrimidine (dbtp) for (5) are reported. These first representatives of paddle-wheel dirhodium complexes with triazolopyrimidines have been characterized by IR and NMR spectroscopy as well as by single-crystal X-ray diffraction studies. Three of the new complexes (1), (2) and (5) were thoroughly screened in vitro for their cytotoxicity against human breast cancer cell line MCF-7 and L929 murine fibroblast cells. Favorably, they show significantly less effective inhibition on the cell growth of L929 than cisplatin under identical conditions. Complexes (1) and (5) display moderate cytotoxic activity (IC50 = 16.3-21.5 µM) against MCF-7 cells which is induced via reactive oxygen species-independent pathways. Extensive studies of rhodium complexes (1), (2) and (5) against microorganisms have shown that the tested compounds exhibit antibacterial activity against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) while (5) significantly inhibited the growth of Malassezia furfur. The highest antibacterial, and antifungal activity, was observed for (5).

Effect of chlorogenic and gallic acids combined with azoles on antifungal susceptibility and virulence of multidrug-resistant Candida spp. and Malassezia furfur isolates.

Chlorogenic acid (CHA) and gallic acid (GA) are safe natural phenolic compounds that are used as enhancers of some drugs in influencing antioxidant, anticancer, and antibacterial activities. Among fungi, Candida spp. and Malassezia spp. are characterized by an increasing prevalence of multidrug resistance phenomena and by a high morbidity and mortality of their infections. No data are available about the efficacy of CHA and GA combined with azoles on the antifungal susceptibility and on the virulence of both fungi. Therefore, their antifungal and antivirulence effects have been tested in combination with fluconazole (FLZ) or ketoconazole (KTZ) on 23 Candida spp. and 8 M. furfur isolates. Broth microdilution chequerboard, time-kill studies, and extracellular enzymes (phospholipase and hemolytic) activities were evaluated, displaying a synergistic antifungal action between CHA or GA and FLZ or KTZ on C. albicans, C. bovina, and C. parapsilosis, and antagonistic antifungal effects on M. furfur and Pichia kudriavzevii (Candida krusei) isolates. The time-kill studies confirmed the chequerboard findings, showing fungicidal inhibitory effect only when the GA was combined with azoles on Candida strains. However, the combination of phenolics with azoles had no effect on the virulence of the tested isolates. Our study indicates that the combination between natural products and conventional drugs could be an efficient strategy for combating azole resistance and for controlling fungistatic effects of azole drugs.

Comparative study between topically applied irradiated human amniotic membrane in combination with tea tree oil versus topical tioconazole in pityraisis versicolor treatment.

Pityriasis versicolor (PV) is a chronic skin disease caused by virulence activities of Malassezia, a genus of skin-associated yeasts. Traditionally, Tioconazole is used as a topical antifungal for curing PV. Previous investigations cited that human amniotic membrane (HAM), a placental tissue, has antimicrobial and anti-inflammatory activities and is useful as a dressing for healing skin lesions. Moreover, tea tree oil (TTO) has a potent antifungal efficacy. This clinical trial aims to achieve an alternative therapeutic treatment able to kill Malassezia and heal PV lesions using TTO-saturated HAM (TOSHAM), with little application times. This study subjected 120 patients with hypopigmented or hyperpigmented PV lesions; half patients were treated weekly with TOSHAM compared with the others who applying 1% Tioconazole cream daily as a traditional treatment. Microbiological evaluation of in vitro fungicidal activity of TOSHAM versus Tioconazole was carried out against Malassezia furfur culture. The clinical outcomes of this study proved the superior activity of TOSHAM to heal PV lesions than Tioconazole; this was in harmony with microbiological findings. This study approached a novel therapeutic treatment of PV with great outcomes by using TOSHAM.

In vitro activity of carvacrol, cinnamaldehyde and thymol combined with antifungals against Malassezia pachydermatis.

Malassezia pachydermatis is an important opportunistic agent of dermatitis and otitis in dogs. M. pachydermatis is generally treated with topical therapies using combinations of antifungal, antimicrobial and anti-inflammatory agents. We investigated the in vitro activities of carvacrol (CRV), cinnamaldehyde (CIN) and thymol (THY) alone and in combination with antifungal agents (fluconazole, itraconazole, ketoconazole, clotrimazole, miconazole, terbinafine and nystatin) against M. pachydermatis. The assays were performed according to the Clinical and Laboratory Standards Institute (CLSI), using Sabouraud dextrose broth and checkerboard microdilution. The mean fractional inhibitory concentration index (FICI) showed primary synergies for the combinations carvacrol+nystatin, thymol+nystatin, and carvacrol+miconazole (80%). In conclusion, the results obtained indicate that the phytochemicals tested showed relevant in vitro anti-M. pachydermatis activity. Future in vivo experiments are needed to elucidate the safety and therapeutic potential of these combinations.

In vitro antimicrobial activity of seven adjuvants against common pathogens associated with canine otitis externa.

BACKGROUND: An antibiotic adjuvant is a chemical substance used to modify or augment the effectiveness of primary antimicrobial agents against drug-resistant micro-organisms. Its use provides an alternative approach to address the global issue of antimicrobial resistance and enhance antimicrobial stewardship. HYPOTHESIS/OBJECTIVES: To determine the antimicrobial activity of a panel of potential antimicrobial adjuvants against common pathogens associated with canine otitis externa (OE). ANIMALS/ISOLATES: A number of type strains and clinical isolates (n = 110) from canine OE were tested including Staphylococcus pseudintermedius, ß-haemolytic Streptococcus spp., Pseudomonas aeruginosa, Proteus mirabilis and Malassezia pachydermatis. METHODS AND MATERIALS: Antimicrobial activities of monolaurin, monocaprin, N-acetylcysteine (NAC), polymyxin B nonapeptide, Tris-EDTA, Tris-HCL and disodium EDTA were tested using microdilution methodology according to CLSI guidelines. RESULTS: N-acetylcysteine, Tris-EDTA and disodium EDTA had antimicrobial activity against both type strains and otic pathogens. The other adjuvants tested had limited to no efficacy. NAC had a minimal inhibitory concentration (MIC) range of 2,500-10,000 µg/mL for the various organisms. Pseudomonas aeruginosa isolates were eight times more susceptible to disodium EDTA in the presence of Tris-HCL in comparison to disodium EDTA alone. Malassezia pachydermatis isolates were most susceptible to Tris-EDTA (MIC90  = 190/60 µg/mL) and disodium EDTA (MIC90  = 120 µg/mL). CONCLUSIONS AND CLINICAL RELEVANCE: N-acetylcysteine, Tris-EDTA and disodium EDTA have intrinsic antimicrobial activity and represent promising adjuvants that could be used to enhance the efficacy of existing antibiotics against Gram-negative and multidrug-resistant bacterial infections. These agents could be combined with other antimicrobial agents in a multimodal approach for mixed ear infections in dogs.

Microwave-mediated synthesis of zinc oxide nanoparticles: a therapeutic approach against Malassezia species.

A successful protocol was developed to aid in the reduction in dandruff-causing fungi, namely Malassezia globasa and Malassezia furfur. Both the species were isolated from volunteers aged between 20 and 22 suffering from dandruff, cultured ex vivo, and tested against the presence of synthesised zinc oxide nanoparticles (ZnNP). Direct microscopy, scanning electron microscopy (SEM), and biochemical assays specific to Malassezia species were conducted to identify dandruff-causing fungal species. Microwave-mediated synthesis of ZnNP was performed and characterised by UV-vis, X-ray diffraction, and SEM. The nanoparticles were tested against both Malassezia species and proved highly effective in inhibiting these fungi, although M. furfur was more susceptible than M. globosa. An optimum amount of 100 ppm was found to be sufficient to work as an antifungal agent. Synergistic effects of ZnNP with commercial shampoos were tested, and the result showed enhanced antifungal effects. To mimic the natural biofilm formed by these species on human skin, the formation of fungal biofilm was allowed on polystyrene coverslips. ZnNP was effective in eradication biofilm. Since zinc is an essential mineral for all living organism and is considered as biocompatible, the synthesised nanomaterials can be used in the formulation of antidandruff shampoos.

Malassezia pachydermatis from animals: Planktonic and biofilm antifungal susceptibility and its virulence arsenal.

The yeast Malassezia pachydermatis is a component of the microbiota of dogs and cats, however it can cause otitis and seborrheic dermatitis in these animals. The objective of this study was to determine the antifungal susceptibility, and evaluate virulence and pathogenicity of 25 M. pachydermatis strains from animals. Susceptibility to ketoconazole, fluconazole, itraconazole, voriconazole, terbinafine, and amphotericin B was evaluated by broth microdilution assay. In addition, biofilm-forming ability, protease, phospholipase, hemolysin and melanin production and adhesion to epithelial cells by this yeast species were assessed. Finally, strain pathogenicity was investigated using the nematode Caenorhabditis elegans. Concerning the planktonic susceptibility, minimum inhibitory concentrations varied from <0.03 to>64 µg/mL for azole derivatives, 1 to >16 µg/mL for amphotericin B and 0.03 to 0.25 µg/mL for terbinafine. All strains were classified as strong biofilm producers, and ketoconazole, fluconazole and amphotericin B presented the best inhibitory effect against mature biofilms. All fungal isolates produced proteases, whereas 14/25 strains were positive for phospholipase production. Hemolytic activity was not observed and 18/25 strains showed dark pigmentation in the presence of L-DOPA. Regarding adhesion to epithelial cells, a low adhesion rate was observed in 10/12 evaluated strains. C. elegans mortality rate reached 95.9% after 96 h of exposure of the worms to M. pachydermatis. This yeast species produces important virulence factors and presents high pathogenicity, corroborating its clinical importance.

The Prevalence of Malassezia Folliculitis in Patients with Papulopustular/Comedonal Acne, and Their Response to Antifungal Treatment.

Because Malassezia folliculitis (MF) may clinically mimic acne vulgaris (AV), patients usually receive unnecessary and prolonged antibiotic treatment. We aimed to determine the prevalence of MF among patients with AV, and to evaluate its response to antifungal treatment. A total of 217 patients with AV underwent cytologic examination for the presence of Malassezia yeasts. Samples were obtained from lesional and nonlesional skin and stained with May-Grünwald-Giemsa. MF was diagnosed if there were more than six spores in one microscopic field (at ×400 magnification). A modified "lesion-counting" method was used to assess the clinical severity of acne. Treatment included oral itraconazole (2×100 mg daily) and topical ketaconazole for 4 weeks. Fifty-five (25.3%) patients were diagnosed with MF; of these, 38 (69.1%) completed the antifungal treatment. The lesions decreased by 50% or more in 26 (68.4%) of the patients who completed the antifungal treatment, which reduced the number of closed comedones/comedolike or molluscoid papules and inflammatory papules. The average number of spores in lesional samples was significantly decreased after treatment (P=<.0005). We observed that MF can present with AV-like lesions, or the two diseases may coexist. Cytology is helpful for making the correct diagnosis and providing proper management of MF.

Novel Naja atra cardiotoxin 1 (CTX-1) derived antimicrobial peptides with broad spectrum activity.

Naja atra subsp. atra cardiotoxin 1 (CTX-1), produced by Chinese cobra snakes, belonging to Elapidae family, is included in the three-finger toxin family and exerts high cytotoxicity and antimicrobial activity too. Using as template mainly the tip and the subsequent ß-strand of the first "finger" of this toxin, different sequences of 20 amino acids linear peptides have been designed in order to avoid toxic effects but to maintain or even strengthen the partial antimicrobial activity already seen for the complete toxin. As a result, the sequence NCP-0 (Naja Cardiotoxin Peptide-0) was designed as ancestor and subsequently 4 other variant sequences of NCP-0 were developed. These synthesized variant sequences have shown microbicidal activity towards a panel of reference and field strains of Gram-positive and Gram-negative bacteria. The sequence named NCP-3, and its variants NCP-3a and NCP-3b, have shown the best antimicrobial activity, together with low cytotoxicity against eukaryotic cells and low hemolytic activity. Bactericidal activity has been demonstrated by minimum bactericidal concentration (MBC) assay at values below 10 µg/ml for most of the tested bacterial strains. This potent antimicrobial activity was confirmed even for unicellular fungi Candida albicans, Candida glabrata and Malassezia pachydermatis (MBC 50-6.3 µg/ml), and against the fast-growing mycobacteria Mycobacterium smegmatis and Mycobacterium fortuitum. Moreover, NCP-3 has shown virucidal activity on Bovine Herpesvirus 1 (BoHV1) belonging to Herpesviridae family. The bactericidal activity is maintained even in a high salt concentration medium (125 and 250 mM NaCl) and phosphate buffer with 20% Mueller Hinton (MH) medium against E. coli, methicillin resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa reference strains. Considering these in vitro obtained data, the search for active sequences within proteins presenting an intrinsic microbicidal activity could provide a new way for discovering a large number of novel and promising antimicrobial peptides families.

Liquid and Vapor-Phase Activity of Artemisia annua Essential Oil against Pathogenic Malassezia spp.

Artemisia annua essential oil has given us many encouraging results for its numerous antimicrobial properties. In this study, the essential oil, both in liquid and in vapor phases, was tested against various Malassezia species closely related to many skin disorders in humans and animals. Malassezia treatment and eradication are mainly based on old azole drugs, which are characterized by poor compliance, unpredictable clinical efficacy, emerging resistance, and several side effects. Monoterpenes (ca. 88%) represent the most abundant group of compounds in the essential oil, mainly the oxygenated derivatives (ca. 74%) with camphor (25.2%), 1,8-cineole (20%), and artemisia ketone (12.5%). In vapor phase, monoterpenes represent more than 98% of the constituents, α-pinene being the main constituent (22.8%), followed by 1,8-cineole (22.1%) and camphene (12.9%). Essential oil of A. annua, both in vapor phase and liquid, showed strong antimicrobial activity towards almost the tested twenty strains of Malassezia analyzed. The minimum fungicidal concentrations from most of the strains tested were from 0.78 µL/mL to 1.56 µL/mL, and only three strains of Malassezia sympodialis required a higher concentration of 3.125 µL/mL. Overall, the minimal inhibitor concentrations obtained by vapor diffusion assay were lower than those obtained by the liquid method. The average values of minimal inhibitor concentrations obtained by the two methods at 72 h are 1.3 - 8.0 times higher in liquid compared to those in the vapor phase.

Antifungal Activity of Thapsia villosa Essential Oil against Candida, Cryptococcus, Malassezia, Aspergillus and Dermatophyte Species.

The composition of the essential oil (EO) of Thapsia villosa (Apiaceae), isolated by hydrodistillation from the plant's aerial parts, was analysed by GC and GC-MS. Antifungal activity of the EO and its main components, limonene (57.5%) and methyleugenol (35.9%), were evaluated against clinically relevant yeasts (Candida spp., Cryptococcus neoformans and Malassezia furfur) and moulds (Aspergillus spp. and dermatophytes). Minimum inhibitory concentrations (MICs) were measured according to the broth macrodilution protocols by Clinical and Laboratory Standards Institute (CLSI). The EO, limonene and methyleugenol displayed low MIC and MFC (minimum fungicidal concentration) values against Candida spp., Cryptococcus neoformans, dermatophytes, and Aspergillus spp. Regarding Candida species, an inhibition of yeast-mycelium transition was demonstrated at sub-inhibitory concentrations of the EO (MIC/128; 0.01 µL/mL) and their major compounds in Candida albicans. Fluconazole does not show this activity, and the combination with low concentrations of EO could associate a supplementary target for the antifungal activity. The association of fluconazole with T. villosa oil does not show antagonism, but the combination limonene/fluconazole displays synergism. The fungistatic and fungicidal activities revealed by T. villosa EO and its main compounds, associated with their low haemolytic activity, confirm their potential antimicrobial interest against fungal species often associated with human mycoses.

Synergistic antimicrobial activity of Boswellia serrata Roxb. ex Colebr. (Burseraceae) essential oil with various azoles against pathogens associated with skin, scalp and nail infections.

Antimicrobials from natural sources have gained immense importance in recent times to combat the global challenge of antibiotic resistance. Essential oils are implicated in antimicrobial action against several species. Here, we have screened nine commercially available essential oils for their antimicrobial activity against organisms associated with skin, scalp and nail infections mainly Propionibacterium acnes, Malassezia spp., Candida albicans and Trichophyton spp. Among nine essential oils, Boswellia serrata essential oil demonstrated superior antimicrobial activity against all the micro-organisms and surprisingly it showed maximum activity against Trichophyton spp. The gas chromatography-mass spectrometry analysis of B. serrata oil indicates a major composition of α thujene, ρ cymene and sabinene. Additionally, B. serrata oil was found to inhibit Staphylococcus epidermidis biofilm, and its combination with azoles has shown synergistic activity against azole-resistant strain of C. albicans. These broad-spectrum antimicrobial activities of B. serrata oil will make it an ideal candidate for topical use. SIGNIFICANCE AND IMPACT OF THE STUDY: Eradication of skin and nail infections still remain a challenge and there are serious concerns regarding the recurrence of the diseases associated with these infections. Antimicrobials from plant sources are gaining importance in therapeutics because they encounter minimal challenges of emergence of resistance. We have demonstrated the antimicrobial activity of Boswellia serrata essential oil against micro-organisms involved in skin, scalp and nail infections, especially if it has shown favourable synergistic antifungal activity in combination with azoles against the azole-resistant Candida albicans strain. Thus, B. serrata oil can be one of the plausible therapeutic agents for management of skin, scalp and nail infections.

Anti-acne, anti-dandruff and anti-breast cancer efficacy of green synthesised silver nanoparticles using Coriandrum sativum leaf extract.

In this present investigation, AgNPs were green synthesised using Coriandrum sativum leaf extract. The physicochemical properties of AgNPs were characterised using UV-visible spectrophotometer, field emission scanning microscopy/energy dispersive X-ray (FESEM/EDX), Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) analysis. Further, in vitro anti-acne, anti-dandruff and anti-breast cancer efficacy of green synthesised AgNPs were assessed against Propionibacterium acnes MTCC 1951, Malassezia furfur MTCC 1374 and human breast adenocarcinoma (MCF-7) cell line, respectively. The flavonoids present in the plant extract were responsible for the AgNPs synthesis. The green synthesised nanoparticles size was found to be ≈37nm. The BET analysis result shows that the surface area of the synthesised AgNPs was found to be 33.72m(2)g(-1). The minimal inhibitory concentration (MIC) of AgNPs for acne causative agent P. acnes and dandruff causative agent M. furfur was found to be at 3.1 and 25µgmL(-1), respectively. The half maximal inhibitory concentration (IC50) value of the AgNPs for MCF-7 cells was calculated as 30.5µgmL(-1) and complete inhibition was observed at a concentration of 100µgmL(-1). Finally, our results proved that green synthesised AgNPs using C. sativum have great potential in biomedical applications such as anti-acne, anti-dandruff and anti-breast cancer treatment.

Is transmission electron microscopy (TEM) a promising approach for qualitative and quantitative investigations of polymyxin B and miconazole interactions with cellular and subcellular structures of Staphylococcus pseudintermedius, Escherichia coli, Pseudomonas aeruginosa and Malassezia pachydermatis?

Antimicrobial therapy using a combination of polymyxin B and miconazole is effective against the main bacterial pathogens associated with otitis externa in dogs, and a synergistic effect of both drugs has been shown previously. The objective of the present investigation was to visualize ultrastructural changes after exposure of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pseudintermedius and Malassezia pachydermatis to polymyxin B and miconazole by transmission electron microscopic (TEM). For this, cultures of E. coli, P. aeruginosa, S. pseudintermedius and M. pachydermatis were exposed to polymyxin B and miconazole, alone or in combination for 24 h. Ultrastructural changes were observed most frequently in the cell envelope of the four microorganisms. Exposure to polymyxin B seemed to cause more damage than miconazole within the range of concentrations applied. Treatment resulted in changes of the cell size: in E. coli, cell size increased significantly after treatment with either compound alone; in P. aeruginosa, cell size decreased significantly after treatment with polymyxin B and with miconazole; exposure of S. pseudintermedius to miconazole caused a decrease in cell size; in M. pachydermatis, cell size increased significantly after treatment with polymyxin B.; in E.coli, S. pseudintermedius and M. pachydermatis, cell size changed highly significant, in P. aeruginosa significantly after exposure to the combination of both compounds. In conclusion, by using a different approach than previous investigations, this study confirmed a clear combinatory effect of polymyxin B and miconazole against the tested microorganisms involved in canine otitis externa. It is the first time that visualization technologies were applied to compare the effect of single drugs to their combinatory effects on cellular and subcellular entities of selected bacterial and yeast species.

Glutathione as a promising anti-hydrophobicity agent against Malassezia spp.

The genus Malassezia has recently attracted wide attention in medical microbiology and dermatology as a pathogen. They are lipophilic yeasts possessing high level of cell surface hydrophobicity (CSH). L-glutathione (GSH) is a ubiquitous antioxidant which offers protection against microbial infections. This study is intended to investigate the role of GSH as a potential anti-hydrophobicity agent against Malazessia spp. Microbial adherence to hydrocarbon assay was performed to assess the anti-hydrophobicity activity (AHA) of GSH against four Malassezia spp. The assay revealed that GSH at 400 µg ml(-1) concentration inhibited CSH, ranging from 84% to 95% in M. furfur, M. globosa, M. restricta and M. sympodialis without killing the cells. The AHA of GSH was corroborated by auto-aggregation assay and zeta-potential measurement, through which delayed cell aggregation was observed due to reduction in CSH level and not by modification in cell surface charge. In addition, colony-forming unit assay was performed in which 62-93% of CSH reduction was observed in Malassezia spp. tested. Furthermore, GSH treatment enhanced the sensitivity of Malassezia spp. towards human blood at the rate of 64-72%. The AHA was further confirmed through Fourier transform infrared analysis. Thus, this study portrays GSH as a prospective therapeutic alternative for Malassezia-mediated infections.