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Background Fungal infections mainly caused by Candida krusei are increasing rapidly and represent a serious public health problem in human immunodeficiency virus (HIV)-infected patients. This study aimed to investigate the antifungal susceptibility profile and virulence factors in C. krusei isolated from HIV-infected patients. Methodology Isolates were identified by biochemical and molecular methods. The antifungal resistance profile was established based on the antifungal susceptibility test performed using the Sensititre YeastOne™ (Thermo Fisher Scientific, Waltham, MA) microdilution technique. The production of phospholipase and proteinase was detected by standard methods. Biofilm formation was performed by the microtiter plate method. Results A total of 73 isolates of C. krusei were recovered from stool, oral swabs, vaginal swabs, and urine samples. The highest number of C. krusei isolates (49, 67.05%)was recovered from stool samples. A total of 32.56% of the C. krusei isolates were multidrug-resistant (MDR). The patients living with HIV and not receiving antiretroviral treatment displayed the highest number of C. krusei isolates (29, 39.76%), whereas the patients living with HIV on antiretroviral therapy exhibited the lowest number of C. krusei isolates (2, 2.72%). All isolates were categorized as strong biofilm producers. Among the production of hydrolytic enzymes, 25 (58.13%) and 24 (55.81%) of C. krusei isolates were classified as strong phospholipase and proteinase producers, respectively. Conclusion The C. krusei isolates obtained in this study were MDR and strongly expressed biofilm formation and both phospholipase and proteinase hydrolytic enzymes. The results show how pathogenic C. krusei is in the HIV-infected population and will contribute toward the management of C. krusei-related infections, which may help improve the life quality of people living with HIV.
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Background: Plants are a rich source of therapeutic compounds that have tremendous applications in the pharmaceutical industry. This study aimed to identify the phytochemicals present in the seven selected medicinal plants as well as their antioxidant and antimicrobial activities. Methods: Phytochemical screening, total phenolic, and flavonoid contents were determined using standard methods. The antioxidant activity of plant extracts was determined using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl (OH), and nitric oxide (NO) radical scavenging assays. The antimicrobial activity of the plant extracts was determined by the broth microdilution method. Results: The results of phytochemical analysis showed the presence of phenols, flavonoids, and steroids in all plant extracts. The extract of Psychotria peduncularis showed the highest total phenolic and flavonoid contents (5.57 ± 0.22 mg GAE/g and 1.38 ± 0.06 mg QE/g, respectively). All plant extracts showed very strong antioxidant activity against DPPH and NO radical scavenging with IC50 values ranging from 0.55 to 49.43 µg/mL and 0.65 to 13.7 µg/mL, respectively. The extracts of Tristemma mauritianum and P. peduncularis displayed significant antibacterial activity with MIC values ranging from 16 to 1024 µg/mL. T. mauritianum extract showed bactericidal activity against all tested species. The extracts of Alsophila manianna and P. peduncularis showed significant antifungal activity (MIC = 64 µg/mL) against Candida albicans strain. Conclusion: The screened extracts of medicinal plants used in our study can be used as potential antioxidant and antimicrobial agents, and resources for the development of new drugs.
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Background: Thymol is an important component of essential oils found in the oil of thyme, is extracted mainly from Thymus vulgaris, and was shown to act synergistically with streptomycin against Klebsiella pneumoniae biofilms. Additionally, thymol could be encapsulated into poly (lactic-co-glycolic acid) (PLGA) nanoparticles to overcome issues related to its low water solubility and high volatility. The present study aimed to investigate the antibiofilm activity of thymol-loaded PLGA nanoparticles (Thy-NPs) alone and in combination with streptomycin against biofilms of K. pneumoniae isolates. Methods: The broth microdilution method was used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The antibiofilm activities were determined by the safranin dye assay. The synergistic effect of Thy-NPs with streptomycin was assessed by the checkerboard method. The kinetic study of the biofilm biomass and time-kill assay were further performed. Results: Thy-NPs exhibited the highest antibacterial activity against K. pneumoniae isolates, with MIC values ranging from 1 to 8 µg/mL. Additionally, Thy-NPs showed the highest antibiofilm activity against K. pneumoniae isolates with minimal biofilm inhibitory concentration (MBIC) and minimal biofilm eradication concentration (MBEC) values ranging from 16 to 64 µg/mL and from 32 to 128 µg/Ml, respectively. The combination treatment combining Thy-NPs with streptomycin showed a synergistic effect against the inhibition of biofilm formation and eradication of biofilms of K. pneumoniae isolates with fractional inhibitory concentration index values ranging from 0.13 to 0.28. In addition, the MBIC and MBEC values of streptomycin against K. pneumoniae isolates were dramatically reduced (up to 128-fold) in combination with Thy-NPs, suggesting that Thy-NPs would enhance the antibiofilm activity of streptomycin. The biomass and time-kill kinetics analysis confirmed the observed synergistic interactions and showed the bactericidal activity of streptomycin in combination with Thy-NPs. Conclusions: Our results indicate that the synergistic bactericidal effect between streptomycin and Thy-NPs could be a promising approach in the control of biofilm-associated infections caused by K. pneumoniae.