Conference Papers (Medical Bioscience)

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Browsing by Author "Africa, Charlene Wilma Joyce"

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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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    Colistin, Carbapenem and Cephalosporin-resistant Klebsiella pneumoniae reported from Misrata, Libya
    (Medpharm Publications, 2017) Shallouf, Mohamed; Abrantes, Pedro Miguel dos Santos; Fielding, Burtram Clinton; Africa, Charlene Wilma Joyce
    Background: National surveillance of antimicrobial resistance has become a mandatory approach to control the spread of antimicrobial resistance and for the establishment of antibiotic treatment guidelines. In this study, clinical isolates of K. pneumoniae were phenotypically investigated for the presences of Colistin and beta-lactams resistance. Methods: Clinical samples were obtained from hospitalized (n=140) and non-hospitalized patients (n=60) in Misrata, Libya. Identification of the isolated species was achieved using the VITEK 2 compact system. Screening for Carbapenem and Cephalosporin-resistance was performed using the disk diffusion method with Carbapenem (10µg) and Cephalosporin (30µg) disks and Minimum Inhibitory Concentration (MIC) determined by VITEK 2. Colistin resistance was determined using both Sensititre Gram-negative Xtra plate format (GNX2F) and VITEK 2. Carbapenemase activity was detected using the RAPIDEC CARBA NP, Modified Hodge test, Carbapenem inactivation method, MAST Combi Carba plus kit (D73C) and Meropenem combined disk test. ESBL and AmpC production was confirmed using Sensititre ESBL confirmatory plates (ESB1F), modified double disk synergy test MDDST, MAST ESBL detection kit D67C, AmpC & ESBL detection kit D68C along with AmpC detection kit D69C. Results and conclusion: Of the 200 clinical isolates, 85 (42.5%) were K. pneumoniae of which 54 (63.52%) demonstrated resistance to at least one of the Carbapenems, 16 (18.82%) were ESBL or AmpC producers and 2 (2.35%) were Carbapenem and Colistin resistant. 13 (21.25%) isolates were susceptible to all antibiotics tested except Ampicillin and Augmentin.
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    Real-time assessment of Candida biofilm disruption by Galenia africana
    (2022-05-25) Stuurman, Keith; Abrantes, Pedro Miguel dos Santos; Klaasen, Jeremy; Africa, Charlene Wilma Joyce
    Candida species often cause opportunistic infections in immunocompromised patients and are able to form highly structured biofilms that protect the yeast cells from the external environment and the action of antimicrobials. The use of fluconazole, a routinely dispensed antifungal in the treatment of localised and systemic Candida infections, often leads to treatment failure due to drug resistance. This increases patient morbidity and mortality and justifies the need for effective and accessible treatment alternatives. Galenia africana is an indigenous South African plant with proven antifungal properties and no toxicity to mammalian cells. In this study the activity of a G. africana aqueous extract against C. albicans and C. glabrata biofilms before and after biofilm formation was tested using the xCELLigence impedance-based real-time biofilm monitoring system. The presence of G. africana resulted in a dose-dependent decrease in biofilm formation in both Candida species and was found to be effective in preventing Candida biofilm formation and disrupting existing Candida biofilms. This is the first reported study to use an impedance-based system to monitor the real-time biofilm formation of Candida species in the presence of a medicinal plant extract.
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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.