Silver nanoparticles, a promising treatment against clinically important fluconazole-resistant Candida glabrata.

Resistance to azole antifungal agents is a challenging limitation in Candida glabrata treatment. It is associated with decreased intracellular concentrations of antifungal agents as a result of overexpression of efflux pumps on the cellular plasma membranes. This work evaluates the potential of silver nanoparticles (AgNPs) to reverse the resistance of fungal cells to fluconazole. Silver nanoparticles were prepared using wet chemical method and characterised by UV-Vis spectrophotometry, dynamic light scattering, and zeta potential. Broth microdilution and pour plates methods were used to study the anticandidal activity using two C. glabrata fluconazole-resistant strains (DSY565 and CBS138) known to overexpress active efflux pumps, and a standard fluconazole sensitive strain ATCC 22553. Silver nanoparticles-fluconazole combinations decreased concentrations of fluconazole substantially without compromising the activity. These findings suggest that AgNPs enhance the efficacy of fluconazole and offer a promising application in therapy of C. glabrata infections.

The effects of some formulation factors used in ophthalmic preparations on thiomersal activity against Pseudomonas aeruginosa and Staphylococcus aureus.

AIMS: To investigate the effects of formulation ingredients used in ophthalmic preparations on thiomersal activity against Staphylococcus aureus and Pseudomonas aeruginosa. METHODS AND RESULTS: Minimum inhibition concentrations (MICs) of the tested ingredients and their combinations were studied using partial broth dilution checkerboard method. Complex formation was determined using differential scanning calorimetry (DSC) and u.v. scan. Isotonic agents showed insignificant difference in thiomersal activity. Low concentrations of propylene glycol and glycerol (2 to about 6.5%) significantly reduced the activity of thiomersal against P. aeruginosa. Higher concentrations up to about 40%, of the two cosolvents did not affect the antibacterial activity. Viscosity increasing agents significantly reduced the antibacterial activity of thiomersal. Low concentrations of 0.05% and 0.05-0.1% of ethylenediaminetetraacetic acid resulted in a significant decrease in thiomersal activity against S. aureus and P. aeruginosa, respectively. However, concentrations above 0.25 and 0.5 up to 4% caused significant increase on the antibacterial activity against the two later micro-organisms, respectively. CONCLUSIONS: Results showed that thiomersal formed complexes with ingredients containing polyhydroxy groups and chelating agents, thus thiomersal is not recommended to be used with such ingredients. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlighted the importance of proper selection of ingredients and preservatives for ophthalmic preparations.

Screening of antibiotic resistant inhibitors from local plant materials against two different strains of Pseudomonas aeruginosa.

The methanolic extracts of 19 Jordanian plants were combined with seven different antibiotics and applied to check the inhibitory effects of the combination on the resistance of Pseudomonas aeruginosa. A resistant strain of Ps. aeruginosa, which was isolated from a patient and a standard strain of the same microorganism were used in this study. Our results showed that there are significant variations in the effects of some combinations used on the resistant and the standard strains probably due to structural changes. Almost all the plant materials used in combination with penicillin G and erythromycin allowed full growth of the standard strain, while the combination with some plant materials like Gundelia tournefortii L. and Lepidium sativum L. inhibited the growth of the resistant strain. Chloramphenicol, gentamicin and cephalosporin can be given advantageously with almost all the plant materials used with few exceptions on the resistant strain. Nalidixic acid activity was improved significantly when combined with all plant materials and tested on standard strain. On the other hand, its activity on the resistant strain was slightly improved using the same combinations.