Significant Reduction Of CFUs Research Articles

Ambisome shows potent anti-Candida auris in vitro and in vivo activity

Candida auris is an emerging multidrug resistant Candida species that has been reported in many parts of the world for causing severe illness in hospitalized patients especially bloodstream infections. The challenge with this type of yeast is its resistance to commonly used antifungal drugs, thus identifying antifungals that are effective against this species is critical. In this study, we determined the in vitro activity of Ambisome against 35 clinical isolates of C. auris using minimum inhibitory concentration (MIC) assay as well as the efficacy of Ambisome compared to Amphotericin B and fluconazole using a C. auris murine disseminated model. Antifungal activity of C. auris against Ambisome and comparators was assessed using amicrodilution method performed according to the Clinical and Laboratory Standard Institute (CLSI) M27-A4 methodology. Mice were immunocompromised and challenged with 3 x 107 C. auris blastopores in 0.1 ml of normal saline (via the tail vein). Treatment efficacy was assessed by determining reductions in mortality as well as decrease in tissue fungal burden (CFUs). Ambisome showed lower MIC50 and MIC90 values (1 and 2 μg/mL, respectively) than the comparators tested. Significant efficacy was observed in the Ambisome 7.5 mg/kg -treated group (100% and 90% survival by day 7- and 14-days post inoculation, respectively). Additionally, Ambisome and fluconazole treated groups showed significant reduction in CFUs in the kidneys (P- values of 0.028 and 0.022, respectively) compared to the untreated group. Our data shows that Ambisome shows significant antifungal activity against C. auris in vitro as well as in vivo.

Role of CpALS4790 and CpALS0660 in Candida parapsilosis Virulence: Evidence from a Murine Model of Vaginal Candidiasis.

The Candida parapsilosis genome encodes for five agglutinin-like sequence (Als) cell-wall glycoproteins involved in adhesion to biotic and abiotic surfaces. The work presented here is aimed at analyzing the role of the two still uncharacterized ALS genes in C. parapsilosis, CpALS4790 and CpALS0660, by the generation and characterization of CpALS4790 and CpALS066 single mutant strains. Phenotypic characterization showed that both mutant strains behaved as the parental wild type strain regarding growth rate in liquid/solid media supplemented with cell-wall perturbing agents, and in the ability to produce pseudohyphae. Interestingly, the ability of the CpALS0660 null mutant to adhere to human buccal epithelial cells (HBECs) was not altered when compared with the wild-type strain, whereas deletion of CpALS4790 led to a significant loss of the adhesion capability. RT-qPCR analysis performed on the mutant strains in co-incubation with HBECs did not highlight significant changes in the expression levels of others ALS genes. In vivo experiments in a murine model of vaginal candidiasis indicated a significant reduction in CFUs recovered from BALB/C mice infected with each mutant strain in comparison to those infected with the wild type strain, confirming the involvement of CpAls4790 and CpAls5600 proteins in C. parapsilosis vaginal candidiasis in mice.

CpALS4770 and CpALS4780 contribution to the virulence of Candida parapsilosis

The ability of yeast to adhere to biotic and abiotic surfaces represents an essential trait during the early stages of infection. Agglutinin-like sequence (Als) cell-wall proteins play a key role in adhesion of Candida species. Candida parapsilosis genome encompasses 5 ALS members, of which only the role of CPAR2_404800 has been elucidated. The present project was aimed at investigating the contribution of C. parapsilosis Als proteins by generating edited strains lacking functional Als proteins. CPAR2_404770 and CPAR2_404780, further indicated as CpALS4770 and CpALS4780, were selected for the generation of single and double edited strains using an episomal CRISPR/Cas9 technology. Phenotypic characterization of mutant strains revealed that editing of both genes had no impact on the in vitro growth of C. parapsilosis or on morphogenesis. Notably, CpALS4770-edited strain showed a reduction of biofilm formation and adhesive properties to human buccal cells (HBECs). Conversely, single CpALS4780-edited strain did not show any difference compared to the wild-type strain in all the assays performed, while the double CpALS4770-CpALS4780 mutant revealed an increased ability to produce biofilm, a hyper-adhesive phenotype to HBECs, and a marked tendency to form cellular aggregates. Murine vaginal infection experiments indicated a significant reduction in CFUs recovered from BALC/c mice infected with single and double edited strains, compared to those infected with the wild-type strain. These finding clearly indicate that CpAls4770 plays a role in adhesion to biotic and abiotic surfaces, while both CpALS4770 and CpALS4780 genes are required for C. parapsilosis ability to colonize and persist in the vaginal mucosa.

Efficacy of Antimicrobial Photodynamic Therapy in Denture Stomatitis: Report of Two Cases

Denture stomatitis (DS) is a common lesion, and of its numerous etiological factors, the Candida species is important. Several strategies are adopted for its treatment; antimicrobial photodynamic therapy (aPDT) is a promising treatment that produces cytotoxic reactive oxygen species, inducing microbial killing. The aim was to report the efficacy of aPDT in 2 patients with DS associated with Candida species. Measurement of clinical effectiveness and microbiologic evaluation were performed by using samples from the palatal mucosa and the prosthesis, inoculated in Sabouraud dextrose agar and CHROMagar Candida to determinate colony-forming units (CFU/mL). The patients were treated with 5 sessions of aPDT with 0.01% methylene blue and were irradiated with a laser at 660 nm (InGaAlP, 4J, 100mW; Photon lase III, DMC, São Paulo). The patients showed clinical remission of DS and significant reduction of CFUs. Thus, aPDT may be a promising option for DS associated with Candida species.

Comparative study of novel in situ decorated porous chitosan-selenium scaffolds and porous chitosan-silver scaffolds towards antimicrobial wound dressing application

Dermal defects caused by trauma or disease are challenging to treat due to difficult-to-treat infections that impair wound healing. Due to the widespread emergence of drug-resistant bacteria and dwindling discoveries of new antibiotics, there is currently an urgent need to introduce novel antimicrobials effective against antibiotic-resistant bacteria without causing damage to host tissues. As selenium (Se) and silver (Ag) are known for their antimicrobial properties, we investigated the separate loading of these materials into porous chitosan/PVA (CS) scaffolds through a simple in situ deposition method to create two distinct wound dressing materials (CS-Se and CS-Ag). Scaffolds with Se nanostructures and scaffolds containing Ag nanostructures were characterized and their activities against S. aureus – (a Gram-positive bacterium), E. coli – (a Gram-negative bacterium) and Methicillin-Resistant S. aureus (MRSA) – (a multi-drug resistant bacterium) were compared. The release of Ag and Se in vitro was shown to depend strongly on the release medium used (deionised water, mammalian or bacterial culture media). Ag-loaded scaffolds showed a significant reduction in CFUs and cytotoxicity towards fibroblasts while Se-loaded scaffolds showed abilities to damage bacterial cell membrane and non-toxicity to fibroblast. Overall, in this study we have demonstrated simple, in situ immobilization porous CS scaffolds with either Se or Ag nanostructures which could be used to suit different wound healing applications.