Early Candida colonisation impact on patients and healthcare professionals in an intensive care unit.

OBJECTIVES: Candida spp. is an opportunistic pathogen that causes superficial and invasive infections with nosocomial outbreaks without strict hygiene protocols. Herein, we assessed oral colonisation by Candida spp. in 209 Intensive Care Unit (ICU) patients between July 2021 and April 2022, conducting clinical, epidemiological, and microbiological characterisation of those developing oral or invasive candidiasis. METHODS: Initial oral swabs were collected within 24 h of admission in the ICU, followed by collections on Days 2, 4, 6 and 8. Swabs from denture-wearing patients, abiotic surfaces, healthcare professionals' hands, and retroauricular regions were also obtained. Recovered yeasts and filamentous fungi were identified using MALDI-TOF MS and morphological characteristics, respectively. Genetic similarity of Candida spp. isolates was evaluated using Amplified fragment length polymorphism (AFLP), and the antifungal susceptibility profile was determined by broth microdilution. RESULTS: In the study, 64.11% of patients were orally colonised by Candida spp. Of these, 80.59% were colonised within the first 24 h. Oral colonisation also occurred on subsequent days: 50%/Day 2, 26.92%/Day 4, and 11.53%/Days 6 and 8. Of the patients, 8.61% had oral candidiasis, mainly pseudomembranous. Among orally colonised patients, 2.23% developed invasive candidiasis. Besides, 89.47% of healthcare professionals evaluated were colonised. MALDI-TOF MS identified different yeast species, and C. albicans (45.34%), C. tropicalis (15.7%), and C. parapsilosis sensu stricto (9.88%) were the most prevalent. AFLP analysis indicated a high genetic correlation (≥97%) between C. parapsilosis sensu stricto isolates from patients and professionals. Three resistant C. albicans isolates were also found. CONCLUSION: This study reported a diversity of yeast and filamentous fungi species in ICU patients and highlighted early Candida spp. colonisation risks for invasive candidiasis, as well as the potential horizontal transmission in the nosocomial setting, emphasising the need for effective infection control measures.

Evolution of a functionally intact but antigenically distinct DENV fusion loop.

A hallmark of dengue virus (DENV) pathogenesis is the potential for antibody-dependent enhancement, which is associated with deadly DENV secondary infection, complicates the identification of correlates of protection, and negatively impacts the safety and efficacy of DENV vaccines. Antibody-dependent enhancement is linked to antibodies targeting the fusion loop (FL) motif of the envelope protein, which is completely conserved in mosquito-borne flaviviruses and required for viral entry and fusion. In the current study, we utilized saturation mutagenesis and directed evolution to engineer a functional variant with a mutated FL (D2-FL), which is not neutralized by FL-targeting monoclonal antibodies. The FL mutations were combined with our previously evolved prM cleavage site to create a mature version of D2-FL (D2-FLM), which evades both prM- and FL-Abs but retains sensitivity to other type-specific and quaternary cross-reactive (CR) Abs. CR serum from heterotypic (DENV4)-infected non-human primates (NHP) showed lower neutralization titers against D2-FL and D2-FLM than isogenic wildtype DENV2 while similar neutralization titers were observed in serum from homotypic (DENV2)-infected NHP. We propose D2-FL and D2-FLM as valuable tools to delineate CR Ab subtypes in serum as well as an exciting platform for safer live-attenuated DENV vaccines suitable for naïve individuals and children.

Candida-associated denture stomatitis: clinical, epidemiological, and microbiological features.

OBJECTIVE: The identification of Candida spp. in denture stomatitis, the clinical manifestations, and the antifungal susceptibility profile lead to a correct and individualized therapeutic management of the patients. This study is aimed at investigating the clinical manifestations and epidemiological and microbiological characteristics of Candida-associated denture stomatitis. DESIGN: The samples were obtained by swabbing the oral mucosa of the subjects and then seeded onto Sabouraud Dextrose Agar and onto CHROMagar® Candida plates. The identification at the species level was confirmed by Matrix Assisted Laser Desorption Time of Flight Mass Spectrometry. Clinical classification was performed according to the criteria proposed by Newton (1962): (i) pinpoint hyperemia, (ii) diffuse hyperemia, and (iii) granular hyperemia. For carrying out the antifungal susceptibility testing, we adopted the CLSI M27-S4 protocol. RESULTS: C. albicans was the most prevalent species in our study. Regarding non-albicans Candida species, C. glabrata was the most common species isolated from the oral mucosa (n = 4, 14.8%), while in the prosthesis, it was C. tropicalis (n = 4, 14.8%). The most prevalent clinical manifestation was pinpoint hyperemia and diffuse hyperemia. Candida albicans, C. glabrata, and C. parapsilosis were susceptible to all the tested antifungals. Concerning fluconazole and micafungin, only two strains showed dose-dependent sensitivity (minimum inhibitory concentration (MIC), 1 µg/mL) and intermediate sensitivity (MIC, 0.25 µg/mL). One C. tropicalis strain was resistant to voriconazole (MIC, 8 µg/mL). CONCLUSIONS: C. albicans was the most common species found in oral mucosa and prosthesis. The tested antifungal drugs showed great activity against most isolates. The most prevalent clinical manifestations were Newton's type I and type II.

Evolution of a Functionally Intact but Antigenically Distinct DENV Fusion Loop.

A hallmark of Dengue virus (DENV) pathogenesis is the potential for antibody-dependent enhancement, which is associated with deadly DENV secondary infection, complicates the identification of correlates of protection, and negatively impacts the safety and efficacy of DENV vaccines. ADE is linked to antibodies targeting the fusion loop (FL) motif of the envelope protein, which is completely conserved in mosquito-borne flaviviruses and required for viral entry and fusion. In the current study, we utilized saturation mutagenesis and directed evolution to engineer a functional variant with a mutated FL (D2-FL) which is not neutralized by FL-targeting monoclonal antibodies. The FL mutations were combined with our previously evolved prM cleavage site to create a mature version of D2-FL (D2-FLM), which evades both prM- and FL-Abs but retains sensitivity to other type-specific and quaternary cross-reactive (CR) Abs. CR serum from heterotypic (DENV4) infected non-human primates (NHP) showed lower neutralization titers against D2-FL and D2-FLM than isogenic wildtype DENV2 while similar neutralization titers were observed in serum from homotypic (DENV2) infected NHP. We propose D2-FL and D2-FLM as valuable tools to delineate CR Ab subtypes in serum as well as an exciting platform for safer live attenuated DENV vaccines suitable for naïve individuals and children.