Conference Papers (Medical Bioscience)

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Browsing by Subject "Candida"

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    Candida species carriage in diabetic patients in Misrata, Libya
    (Medpharm Publications, 2017) Esmaio, Mustafa Hassan Mustafa; Abrantes, Pedro Miguel dos Santos; Africa, Charlene Wilma Joyce
    Background: There is a paucity of studies describing the prevalence and antimicrobial profiles of Candida in Libya. Limited treatment choices in the antifungal armamentarium in public healthcare settings in Africa require a study of the prevalence and susceptibility of Candida species in Libya, where antifungals are not routinely prescribed in public healthcare settings. Methods: In this study, 170 diabetes mellitus type 2 (T2DM) patients were examined for Candida carriage in the oral mucosa, using differential Fluka and Oxoid chromogenic media and API 32 ID C biochemical testing. Fluconazole susceptibility was investigated by disk diffusion on YNBG agar. Isolates were graded as susceptible, intermediate or resistant according to their inhibition zone measurements and microcolony scores. Results: Thirteen species were identified from 182 isolates with a frequency of 68 C. albicans, 42 C. dubliniensis, 26 C. humicola, 20 C. glabrata , 5 isolates of each C. krusei, C. tropicalis and C. kefyr, 4 C. sake, 2 C. parapsilopsis, 2 C. magnoliae and 1 isolate each of C. guilliermondii, C. globosa and C. membranifaciens. Although largely susceptible to fluconazole, C. albicans, C. dubliniensis, C. humicola and C. sake demonstrated an emerging resistance with intermediate to total resistance observed in all the other species except for C. magnolia and C. globosa which were both susceptible to fluconazole. Conclusion: Early recognition and treatment of rare or resistant Candida species which may be contributing to patient morbidity and mortality in Libya is imperative.
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    Proteomics of drug-resistant HIV-associated candidiasis
    (University of the Western Cape, 2015) Abrantes, Pedro Miguel dos Santos; Bouic, Patrick J.D.; Africa, Charlene W.J.
    Candidiasis and HIV co-infection may cause increased patient morbidity and mortality due to oropharyngeal or systemic dissemination. Limited information exists on the prevalence, antifungal susceptibility profiles and drug resistance mechanisms of Candida species on the African continent, the highest HIV-affected region globally and home to new and emerging drug resistant Candida species. Candida species isolated from the oral mucosa of HIV-positive African patients were found to be resistant to many of the antifungals routinely used in HIV-associated candidiasis. Candida cell membrane fractions were examined using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and high performance liquid chromatography mass spectrometry (HPLC/MS) in order to elucidate the cell membrane proteins specifically expressed by antifungal drug resistant isolates. SDS-PAGE and HPLC/MS allowed for the identification of multi-drug resistance efflux transporter CDR2 proteins and the elucidation of Candida colonization mechanisms and pH-responsive proteins, with significant associations observed between specific drug resistance and the duration of antiretroviral (ARV) therapy. This study provided useful information on the mechanisms of antifungal resistance in Candida species. It also formed the basis for further studies to address the transfer of resistance between Candida species in an oral microbial biofilm.
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    Rare fungal species isolated from Libyan diabetic patients
    (Infection Control Africa Network (ICAN), 2016) Esmaio, Mustafa; Abrantes, Pedro Miguel dos Santos; Africa, Charlene W.J.
    BACKGROUND AND OBJECTIVES: The emerging resistance of Candida species to antifungals routinely used to treat candidiasis in HIV patients and in patients with diabetes mellitus (DM) has resulted in the frequent isolation of non-albicans Candida species. This study aimed to establish the prevalence and fluconazole resistance profiles of yeasts other than commonly identified Candida species which may be found colonizing the oral mucosa of Libyan patients with DM. METHODS: Fungal species were isolated from the oral cavity of DM-positive patients attending a diabetes clinic in Misrata Diabetes Centre in Libya. This study included patients aged between 35 and 95 years and excluded subjects who had been on antifungal therapy within two weeks prior to sample collection. The identification of the isolated species was done by growing the isolates on selective and chromogenic media and by API ID 32C biochemical testing. Antimicrobial susceptibility testing of the isolates to the antifungal fluconazole was performed using disk diffusion. The study complied with the Declaration of Helsinki (2013). RESULTS: Forty-four rare fungal isolates representing ten fungal species were identified from the oral mucosa of 194 patients, with 28.6% of rare Candida species demonstrating resistance to fluconazole. Saprochaete capitata and Cryptococcus humicola isolates demonstrated high levels of resistance to fluconazole, with other yeast species showing lower resistance levels. CONCLUSION: The methodologies used in this study allowed for the accurate identification of rare fungal species. The API 32 ID system was found to be a better identification method when compared to chromogenic media, as some species could not be identified with the latter. This study emphasizes the importance of accurate species identification and antifungal surveillance in patients with underlying chronic diseases such as DM who have higher morbidity and mortality rates due to less known and resistant fungal infections.
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    Real-time assessment of Candida biofilm formation
    (Elsevier, 2021-09) Abrantes, Pedro Miguel dos Santos; Behardien, Kauthar; Africa, Charlene Wilma Joyce
    Background: Candida infections are responsible for increased morbidity and mortality in immunocompromised patients, particularly when the Candida biofilm is composed of drug-resistant species. Although the biofilm formation abilities of individual Candida species have been described, the real-time interactions between common and rarer Candida species are yet to be elucidated. Methods: In this study an impedance-based biofilm monitoring systemwas used in comparison with the conventional crystal violet (CV) staining method, for demonstrating the biofilm formation of commonly isolated and less common Candida species. Results: The maximum cell index increased in most mixed biofilms, with the exception of the C. glabrata/C. parapsilosis and C. albicans combinations. Bulk biofilm formation measured by CV stainingwas the highest in C. albicans and C. tropicalis combinations and was the lowest for the C. glabrata/C. parapsilosis combination. Extensive pseudohyphae, which have been associated with increased virulence, were observed in C. albicans and C. glabrata combinations with C. tropicalis or C. parapsilosis. Conclusion: This study appears to be the first to report on the realtime biofilm interactions of Candida species using the xCELLigence system and suggests that the presence of specific species influences the biofilm formation of commonly isolated Candida species. This is important since biofilms act as reservoirs for disseminated infection and as demonstrated in this study, mixed Candida species act in synergy resulting in an increase in biofilm mass and subsequent risk for drug resistance.
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    Vitek characterisation of type 2 diabetes-associated Candida species
    (Elsevier, 2017) Esmaio, Mustafa Hassan Mustafa; Abrantes, Pedro Miguel dos Santos; Africa, Charlene Wilma Joyce
    Background: Type 2 diabetes mellitus (T2DM) predisposes patients to opportunistic infections, such as invasive candidiasis. Treatment of candidiasis is challenged by the emerging resistance of Candida species. In this study, the antifungal drug resistance patterns of Candida species present in the oral mucosa of T2DM Libyan patients was investigated. Methods: Seventy four (74) oral Candida isolates collected from T2DM patients in Misrata, Libya were characterised using the VITEK 2 Compact system. Results: Prevalent species included C. albicans, C. glabrata, C. dubliniensis, C. krusei, C. tropicalis, C. sake, C. kefyr, C. guilliermondii, C. parapsilopsis, C. membranifaciens and C. magnoliae. Drug susceptibility showed an emerging resistance across representatives of all species for which breakpoints were available, with the exception of C. parapsilopsis. Although there are no established interpretative breakpoints for these species, three C. sake isolates and the C. membranifaciens isolate also had high MIC values for fluconazole. The tested isolates were found to be largely susceptible to caspofungin and micafungin. All C. albicans isolates were susceptible to the echinocandins, amphotericin B and 5-flucytosine. Resistance to more than one drug class was seen in C. dubliniensis, C. glabrata and C. krusei isolates. Conclusion: Although the susceptibility results for the echinocandins were encouraging, resistance against the azoles was apparent and should not be ignored. This was especially so in the case of fluconazole, which is often the only locally available antifungal drug for the treatment of disseminated candidiasis.