Antifungal activity of cercosporamide produced by Phaeosphaeriaceae GV-1 against pathogenic fungi

Fungal infections affect millions of people worldwide, and the several cases are related to invasive infections, which is a problem mainly for immunocompromised people, such as transplant and cancer patients with high mortality and morbidity rates. In addition, the number of emerging and multidrug-resistant fungal species has increased in the last decade. The search for new antifungal compounds is necessary, due to the increase in cases of resistance and the toxicity of drugs used in fungal infection treatment. This work aimed to study the antifungal activity of cercosporamide produced by Phaeosphaeriaceae GV-1. Cercosporamide was tested against pathogenic fungi by determining the minimum inhibitory (MIC) and minimum fungicidal (MFC) concentrations, using the broth microdilution method. Cercosporamide showed antifungal activity in vitro against 13 of 16 strains of medical importance tested, with the most susceptible species being Candida tropicalis, with MIC and MFC of 15.6 μg/mL. Thus, cercosporamide might be considered a promising therapeutic antifungal agent.

Spectroscopic characterization and antimicrobial activity of nanoparticle doped cyclodextrin polyurethane bionanosponge

This study reports on the spectroscopic characterization and antimicrobial potency of polyurethane cyclodextrin co-polymerized phosphorylated multiwalled carbon nanotube-doped Ag-TiO₂ nanoparticle (pMWCNT-CD/Ag-TiO₂) bionanosponge nanocomposite. The synthesis of pMWCNT-CD/Ag-TiO₂ bionanosponge nanocomposite was carried out through the combined processes of amidation and polymerization reactions as well as the sol-gel method. The native nanosponge cyclodextrin and phosphorylated multiwalled carbon nanotube-nanosponge CD (pMWCNT-CD) polyurethanes were also prepared, and their antimicrobial activities carried out for comparison purposes. The synthesized bionanosponge polyurethane materials were characterized using Fourier-transform infrared (FTIR) spectroscopy, Laser Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to give clear information regarding their structural, and dynamic physicochemical properties. The potency tests of the synthesized compounds were carried out against three bacterial strains Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and two fungal representatives Aspergillus ochraceus and Aspergillus fumigatus, using the disc diffusion method. Micro dilution and agar plating were used to determine the minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC), respectively. The results obtained revealed that pMWCNT-CD/Ag-TiO₂ exhibits superior antibacterial and antifungal activities when compared to the other bionanosponge polymers tested. Thus, the bionanosponge polyurethane pMWCNT-CD/Ag-TiO₂ nanocomposite can be considered as an active antimicrobial compound (AMC).

In vitro antidermatophytic activity and cytotoxicity of extracts derived from medicinal plants and marine algae

OBJECTIVES

This study was conducted to evaluate the antidermatophytic activity of 48 extracts obtained from medicinal plants (Cibotium barometz, Melastoma malabathricum, Meuhlenbeckia platyclada, Rhapis excelsa, Syzygium myrtifolium, Vernonia amygdalina) and marine algae (Caulerpa sertularioides, Kappaphycus alvarezii) against Trichophyton rubrum and Trichophyton interdigitale (ATCC reference strains), and the cytotoxicity using African monkey kidney epithelial (Vero) cells. Active plant extracts were screened for the presence of phytochemicals and tested against clinical isolates of Trichophyton tonsurans.

METHODS

Six different extracts (hexane, chloroform, ethyl acetate, ethanol, methanol and water) were obtained from each plant or algae sample using sequential solvent extraction. The antidermatophytic activity for the extracts was assessed using a colourimetric broth microdilution method. The viability of Vero cells was measured by Neutral Red uptake assay.

RESULTS

All the extracts (except the water extracts of V. amygdalina, C. sertularioides and K. alvarezii) showed antidermatophytic activity against Trichophyton spp. The minimum fungicidal concentration (MFC) ranges for the plant extracts against T. rubrum and T. interdigitale are 0.0025-2.50 and 0.005-2.50mg/mL, respectively. The algae extracts exhibited lower potency against both species, showing MFC ranges of 0.08-2.50 and 0.31-2.50mg/mL, respectively. The ethanol and methanol extracts from the leaves of R. excelsa, and the methanol and water extracts from the leaves of S. myrtifolium were highly active (MFC<0.1mg/mL) and with high selectivity indices (SI>2.8) against reference strains of T. rubrum and T. interdigitale, and most of the clinical isolates of T. tonsurans. Phytochemical analysis indicates the presence of alkaloids, anthraquinones, flavonoids, saponins, tannins, phenolics and triterpenoids in the extracts.

CONCLUSIONS

The medicinal plant extracts exhibited stronger antidermatophytic activity compared to the algae extracts. The leaves of R. excelsa and S. myrtifolium are potential sources of new antidermatophytic agents against Trichophyton spp.

Antifungal Activity of Xylitol against Candida albicans: An in vitro Study

AIM

The most common fungal infection among human population is candidiasis, the etiology of which is mostly Candida albicans. As a result of a disrupted balance of the normal flora or a compromised immune system, Candida species can become pathogenic. Various in vitro surveys have shown that glucose intake is a promoter of C. albicans growth, whereas in vivo studies have found that xylitol can decrease the risk of candidiasis and angular cheilitis. Hence, we aimed to evaluate for the first time the inhibitory effects of xylitol on C. albicans by assessing its minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC).

MATERIALS AND METHODS

The standard strain of C. albicans was acquired. The fungi were incubated in supplemented brain-heart infusion broth for 48 hours at 37°C. The MIC was measured according to the Clinical and Laboratory Standards Institute (CLSI) M100-S24 standard. Microdilution method was applied using 360-uL sterilized polystyrene flat-bottomed 96-well plates. The antimicrobial effects were examined by the microbroth dilution method according to the CLSI M100-S24 standard.

RESULTS

The MIC of xylitol for C. albicans was found to be 20 × 10⁴ μg/mL. Furthermore, the concentration of 40 × 10⁴ μg/mL with a decrease of 99.95% in the colony-forming units (CFUs) of the microorganism was found to be the MFC of xylitol for C. albicans.

CONCLUSION

According to the results of this survey, xylitol has considerable antimicrobial effects. Hence, this substance can be used as an effective element in gums, toothpastes, and antimicrobial mouthwashes, especially in patients with candidiasis.

CLINICAL SIGNIFICANCE

By knowing the MIC and MFC of xylitol, this substance can be effectively used in products aimed to cure this fungal infection.

Sertraline enhances the activity of antimicrobial agents against pathogens of clinical relevance

BACKGROUND

Serotonin reuptake inhibitors were recently reported to possess antimicrobial potentials, potentiate activity of several antibiotics, reverse multidrug resistant phenotypes of bacteria and make them susceptible to previously resistant drugs. We investigated antimicrobial potentials of sertraline (SR) against ATCC strains, clinical isolates of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa alone and in-combination with seven antibiotics. Antifungal activity was investigated against four fungal strains including Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus, and Fusarium solani. Intrinsic antibacterial action and Minimum Inhibitory Concentrations (MICs) were determined using well assay, nutrient broth and agar dilution techniques. Disk diffusion and nutrient broth methods were used to study bacterial susceptibility to SR. Minimum Fungicidal Concentrations (MFCs) of SR were determined using Sabouraud dextrose Agar (SDA).

RESULTS

Sertraline possesses strong intrinsic antibacterial, antifungal activities and has augmented the antibacterial activities of antibiotics. For S. aureus ATCC 6538, E. coli ATCC 8739 and P. aeruginosa ATCC 9027, the MICs of SR were 20, 40 and 60 μg ml(-1), respectively, whereas 55.5% clinical isolates of S. aureus and 50% of E. coli strains were inhibited at 20 and 60 μg ml(-1) of SR, respectively. Among the tested fungi, 60% of A. niger and A. fumigatus were inhibited at 40 and 80 μg ml(-1), respectively. MFCs were 60 and 80 μg ml(-1) for A. flavus and F. solani, respectively. Antibacterial activities of all antibiotics were significantly increased (p < 0.001) with the addition of SR 100 μg ml(-1) against all tested bacteria.

CONCLUSION

Combination study revealed that SR had significantly increased the activity of antibiotics, and some previously resistant strains were made susceptible. Thus antidepressants are potential sources of resistance modifying agents when used in combination.

Nosocomial Candida parapsilosis candidaemia: risk factors, antifungal susceptibility and outcome

A retrospective analysis was undertaken from 2000 to 2010 to show the risk factors associated with death within 30 days in patients with C. parapsilosis candidaemia (CPC). Fifty-one cases of nosocomial CPC were included in the analysis. All isolates from blood cultures were susceptible to micafungin and fluconazole. The overall mortality rate was 23.5%, and the most severe complications were endocarditis (5.9%) and endophthalmitis (5.9%). On multi-variate analysis, APACHE II score >25 (odds ratio 43.9) and retained cardiovascular prosthetic materials (RCPM) (prosthetic valve or graft) (odds ratio 14.6) were found to be risk factors associated with death. Prompt surgical removal should be considered in CPC patients with RCPM.