Browsing by Author "Abrantes, Pedro Miguel dos Santos"
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Item Antimicrobial resistant Gram-positive cocci in pregnant mothers with aerobic vaginitis(Infection Control Africa Network (ICAN), 2016) Kaambo, Eveline; Abrantes, Pedro Miguel dos Santos; McArthur, Carole P.; Africa, Charlene W.J.The vaginal microbiota of a healthy asymptomatic woman consists of an extensive diversity of anaerobic and aerobic bacterial genera and species dominated by the microaerophilic genus Lactobacillus , known to inhibit the growth of potentially pathogenic non-acid tolerant microorganisms. An imbalance of species within this biofilm may result in endogenous opportunistic infections such as aerobic vaginitis (AV) caused by S. agalactiae and E. faecalis, which have been implicated in neonatal and obstetric sepsis. The prevalence and antimicrobial susceptibility of E. faecalis and S. agalactiae in pregnant women with AV in the Western Cape, South Africa was determined using standard microbiological culture methods and the Sensititre TREK system. AV was detected in 26.13% of the 199 tested pregnant women, with S. agalactiae and E. faecalis isolated from 32 and 20 mothers respectively. S. agalactiae and E. faecalis showed resistance to 12 of the 17 antibiotics tested, including those recommended for prophylaxis according to the CDC guidelines. The resistance of S. agalactiae and E. faecalis to commonly administered antimicrobials highlights the need for alternative treatment regimens for AV during pregnancy to reduce the risk of AV-associated negative pregnancy outcomes.Item Candida antifungal drug resistance in sub-Saharan African populations: A systematic review(Science Navigation Group, 2017) Africa, Charlene W.J.; Abrantes, Pedro Miguel dos SantosBACKGROUND: Candida infections are responsible for increased morbidity and mortality rates in at-risk patients, especially in developing countries where there is limited access to antifungal drugs and a high burden of HIV co-infection. OBJECTIVES: This study aimed to identify antifungal drug resistance patterns within the subcontinent of Africa. METHODS: A literature search was conducted on published studies that employed antifungal susceptibility testing on clinical Candida isolates from sub-Saharan African countries using Pubmed and Google Scholar. RESULTS: A total of 21 studies from 8 countries constituted this review. Only studies conducted in sub-Saharan Africa and employing antifungal drug susceptibility testing were included. Regional differences in Candida species prevalence and resistance patterns were identified. DISCUSSION: The outcomes of this review highlight the need for a revision of antifungal therapy guidelines in regions most affected by Candida drug resistance. Better controls in antimicrobial drug distribution and the implementation of regional antimicrobial susceptibility surveillance programmes are required in order to reduce the high Candida drug resistance levels seen to be emerging in sub-Saharan Africa.Item Candida species carriage in diabetic patients in Misrata, Libya(Medpharm Publications, 2017) Esmaio, Mustafa Hassan Mustafa; Abrantes, Pedro Miguel dos Santos; Africa, Charlene Wilma JoyceBackground: 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.Item Carbapenem resistance expressed by Gram-negative bacilli isolated from a cohort of Libyan patients(BioMed Central, 2016) Shallouf, Mohamed; Abrantes, Pedro Miguel dos Santos; Africa, Charlene W.J.Background and objectives: Carbapenem-resistant Enterobacteriaceae (CRE) and other Gram-negative bacteria are among the most common pathogens responsible for both community and hospital acquired infection. The global spread of cephalosporinases in Enterobacteriaceae has led to the increased use of carbapenems resulting in the emergence and rapid spread of CRE. This has become an alarming public health concern, yet the condition in Libya remains unclear. The aim of this study was to obtain a better understanding of CRE strains prevalent in Libyan patients by investigating their phenotypic characteristics and antibiograms. Methods: Gram-negative bacterial species were collected from Misrata Central Hospital, Misrata Cancer Centre and Privet Pathology Laboratories. Clinical samples and swabs were obtained from hospitalised and non-hospitalised patients and from mechanical ventilation and suction machines. Patients who had received antibiotic therapy for at least three days prior to the study were excluded. The identification and characterization of the isolated species were achieved using the growth characteristics on MacConkey and blood agar, spot tests and API 20E or API 20NE biochemical testing systems. Screening for carbapenem resistance was performed using the disk diffusion method with carbapenem 10 μg and cephalosporin 30 μg disks and minimum inhibitory concentrations (MIC) determined using the Sensititre Gram-negative Xtra plate format (GNX2F). All strains demonstrating resistance or reduced susceptibility to one of the four carbapenems were subjected to carbapenememase activity detection using the RAPIDEC CARBA NP test, Modified Hodge test and carbapenem inactivation methods. Results: A total of one hundred and forty isolates representing fourteen bacterial species were isolated from 140 non-duplicated specimens. Clinical specimens included urine samples (96/140, 68.57%), sputum (15/140, 10.71%), surgical wound swabs (18/140, 12.85%), foot swabs from diabetes mellitus (DM) patients (6/140, 4.29%), ear swabs (3/140, 2.14%) and wound swabs (2/140, 1.43%). Thirty-four (24.29%) isolates demonstrated resistance to at least one of the four carbapenems with Klebsiella pneumoniae representing 73.53% (25 isolates) of all carbapenem resistant species, followed by 8.82% for Pseudomonas aeruginosa (3 isolates), 5.88% for both Proteus mirabilis (2 isolates) and Escherichia coli (2 isolates) and 2.94% for both Citrobacter koseri (1 isolate) and Rahnella aquatilis (1 isolate). The other isolates were either susceptible or cephalosporinase producers. Conclusion: This study has revealed the high rate of carbapenem resistance amongst Libyan patients and emphasizes the crucial need for accurate screening, identification and susceptibility testing to prevent further spread of nosocomial and community acquired resistance. This may be achieved through the establishment of antibiotic stewardship programmes along with firm infection control practices.Item 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 JoyceBackground: 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.Item A comparison of susceptibility patterns of oral Candida isolates from South African and Cameroonian HIV- positive populations(The International Association for Dental Research (IADR), 2012) Abrantes, Pedro Miguel dos Santos; McArthur, Carole P.; Africa, Charlene W.J.METHOD: In this study, Candida isolates were collected from the oral mucosa of 128 South African and 126 Cameroonian HIV-positive patients, by scraping the mouths of consenting patients using sterile cotton swabs. Ethics clearance for this project was granted by the University of the Western Cape. Confirmation of Candida species was done by growth on differential media, Gram staining and microscopy. The isolates were grown on selective media and differentiated using two commercial chromogenic agars and Tomato (V8) agar. Changes in colony colour, morphology and pseudohyphae/chlamydospore expression could then be observed, allowing for species differentiation. Isolates were also examined for antifungal susceptibility patterns using the TREK system. RESULT: The results from this study suggest that the prevalence of Candida species varies according to geographical region and HIV-subtype. Discrepancies in antifungal drug susceptibility patterns were also observed in the two populations. CONCLUSION: The emerging drug-resistance raises the need for increased species prevalence surveillance, as this information can have clinical implications in the choice of more appropriate and effective patient treatment.Item Drug susceptibility profiles of Candida species isolated from the oral mucosa of HIV-positive West African patients using the TREK Sensititre system(2013) McArthur, Carole P.; Abrantes, Pedro Miguel dos Santos; Awasom, Charles; Ayuk, L.; Africa, Charlene W.J.BACKGROUND: Candida infections are a common cause of death in immunocompromised patients. The prevalence and anti-mycotic drug susceptibility profiles of Candida species from Cameroon in Africa are unavailable. This study was prompted by an increasing incidence of treatment failure. Drug susceptibility profiles, necessary to improve treatment outcomes, is particularly important in countries where the sale of antimicrobials and antifungals is uncontrolled and resistance may emerge due to the indiscriminate use. OBJECTIVE: The goal of this study was to characterize and determine drug susceptibility of oral Candida species in Cameroonian patients with HIV/AIDS. MATERIALS AND METHODS: Candida species were isolated from the oral cavity of 126 HIV-positive patients attending a local HIV/AIDS clinic in the Cameroon. Drug susceptibility to azoles and echinocandins was determined using the commercial TREK Sensititre® YeastOne™ platform that provides the minimal inhibitory concentration of amphotericin B, 5-flucytosine, anidulafungin, caspofungin, micafungin, fluconazole, itraconazole, posaconazole, and voriconazole. RESULTS: Ninety two isolates identified were Candida albicans. Remaining isolates were C. glabrata (24), C. tropicalis (4), C. krusei (3), C. parapsilopsis/lusitanreae/keyfr (2), and one isolate was C. dubliniensis. More than 50% of C. albicans isolated were resistant to azoles but 115 Candida species (87%) were susceptible to amphotericin B. Twenty one of the twenty four C.glabrata identified (88%) were resistant to micafungin. The majority of Cameroonian Candida species were sensitive to flucytosine (5-FC) (95%) and echinocandins (79%). CONCLUSIONS: The report of azole resistance in all Candida species isolated from immunocompromised patients in Cameroon is a new and important observation. We found the approach using a broad screening platform an effective means to obtain data rapidly. We propose confirmation of these data and regional surveillance of Candida species in other areas in Cameroon and surrounding countries to develop an effective public health management and treatment strategy.Item HIV/Candida co-infection in Sub-Saharan African women on ART(Infectious Diseases Society of Southern Africa, the Sexually Transmitted Diseases Society of Southern and the Public Health Association of South Africa., 2013) Abrantes, Pedro Miguel dos Santos; Africa, Charlene W.J.INTRODUCTION: Sub-Saharan Africa has 23.5 million cases of HIV and is home to 92% of the world’s HIV-positive pregnant women of whom 24% die of pregnancy related complications. Oral candidiasis is a common condition in HIV-AIDS patients, caused by commensal yeasts which may colonise the mucous membranes of the mouth causing morbidity due to several factors including immunosuppression, smoking, poor nutrition and the use of antibiotics. Methods: One hundred and ninety-four South African and Cameroonian HIV-positive women participated in the study. Only subjects who had white pseudomembranous plaque on the tongue or visible oral candidiasis were included. Samples were collected by scraping the patient’s oral mucosa and tongue with a sterile swab. Candida species were differentiated using selective and chromogenic media and their susceptibility to antifungal drugs was tested using the TREK Sensititre system. Results and conclusion: One hundred and ninety-six isolates, representative of six Candida species were identified. C. albicans was the predominating species, with C. glabrata and C. dubliniensis being the more frequent of the non-albicans isolates. Azole drug resistance patterns were very high for C. albicans, while C. glabrata showed high resistance patterns to echinocandins drugs. The duration of ART could be associated with the presence of different Candida species but no concrete conclusions could be drawn concerning HIV/Candida co-infection when controlling for other risk factors such as HIV stage, pregnancy, age and treatment for tuberculosis. This may be a cause for concern, particularly in the case of pregnancy, where co-infection may pose a risk for maternal morbidity and mortality.Item HPLC-MS identification and expression of Candida drug-resistance proteins from African HIV-infected patients(AIMS Press, 2021-09-10) Abrantes, Pedro Miguel dos Santos; Fisher, Randall; Bouic, Patrick J D; McArthur, Carole P; Fielding, Burtram C; Africa, Charlene Wilma JoyceThe objective of this study was to elucidate the proteomic mechanisms of drug resistance in HIV-infected African patients. Cell membrane fractions from forty oral Candida isolates isolated from African HIV-positive patients were analysed using HPLC-MS with the aim of identifying proteins associated with their pathogenicity and drug resistance. Heat shock proteins that mediate the fungicidal activity of salivary peptides were found in all tested Candida fractions, with pH-responsive proteins associated with increased pathogenicity only being present in the three most commonly isolated species. ABC multidrug transporter efflux pumps and estrogen binding proteins were only found in C. albicans fractions, while ergosterol biosynthesis proteins were identified in four species. The combination of various adherence, invasion, upregulation and efflux pump mechanisms appear to be instrumental for the Candida host colonization and drug resistance emergence in HIV-infected individuals.Item K21 compound, a potent antifungal agent: Implications for the treatment of fluconazole-resistant HIV-associated Candida species(Frontiers, 2019-05-24) John, Cathy Nisha; Abrantes, Pedro Miguel dos Santos; Prusty, Bhupesh; Ablashi, Dharam; Africa, Charlene Wilma JoyceBackground/objectives: With mucocutaneous candidiasis being highly prevalent in HIV patients, the emergence of fluconazole-resistant Candida species forms a major challenge in treating and eradicating these infections. The objective of this study was to establish the antifungal activity of K21, a membrane-rupturing antimicrobial compound derived from a silica quaternary ammonium compound (SiQAC) with tetraethoxysilane (TEOS). Methods: The study sample included 81 Candida species of which 9 were type strains and 72 were clinical isolates. Minimum inhibitory concentrations, synergy, fractional inhibitory concentration index (FICI) and time kill assays were determined by broth microdilution. Electron microscopy (EM) was used to determine the qualitative changes brought about after treatment with K21. Results: K21 inhibited the growth of all fluconazole-resistant and susceptible Candida strains with only 2 hours of exposure required to effectively kill 99.9% of the inoculum, and a definite synergistic effect observed with a combination of K21 and fluconazole. EM demonstrated the presence of two forms of extracellular vesicles indicative of biofilm formation and cell lysis. Conclusion: The study established the efficacy of K21 as an antifungal agent and with fluconazole-resistant candidiasis on the increase, the development of K21 can provide a promising alternative to combat acquired drug resistance.Item Measuring Streptococcus mutans, Streptococcus sanguinis and Candida albicans biofilm formation using a real-time impedance-based system(Elsevier, 2019-12-20) Abrantes, Pedro Miguel dos Santos; Africa, Charlene Wilma JoyceCandida albicans and streptococci are amongst the most common fungal and bacterial organisms present in the oral cavity, with a growing body of evidence implicating C. albicans in increased caries severity and in the formation of the cariogenic biofilm. However, the interactive mechanisms between cariogenic streptococci and Candida are yet to be elucidated. In this study, the real-time biofilm formation of C. albicans, S. mutans and S. sanguinis was assessed individually and in combination using the xCELLigence system, an impedance-based microbial biofilm monitoring system. The impedance signal was the highest for C. albicans, followed by S. mutans and S. sanguinis. Although the streptococcal mixed adhesion was found to follow a similar trend to that of S. sanguinis, the introduction of C. albicans resulted in higher adhesion patterns, with the combined growth of S. sanguinis and C. albicans and the combination of all three species resulting in higher biofilm formation than any of the individual organisms over time. This study, the first to use impedance for real-time monitoring of interkingdom biofilms, adds to the body of evidence that C. albicans and oral streptococcal adhesion are interlinked and suggests that interkingdom interactions induce changes in the oral biofilm dynamics over time.Item Multi-drug resistant (MDR) oral Candida species isolated from HIV-positive patients in South Africa and Cameroon(Elsevier, 2014) Abrantes, Pedro Miguel dos Santos; McArthur, Carole P.; Africa, Charlene W.J.Candida species are a common cause of infection in immune-compromised HIV-positive individuals, who are usually treated with the antifungal drug, fluconazole in public hospitals in Africa. However, information about the prevalence of drug resistance to fluconazole and other antifungal agents on Candida species is very limited. This study examined 128 Candida isolates from South Africa and 126 Cameroonian Candida isolates for determination of species prevalence and antifungal drug susceptibility. The isolates were characterized by growth on chromogenic and selective media and by their susceptibility to nine antifungal drugs tested using the TREK™ YeastOne9 drug panel (Thermo Scientific). Eighty three percent (82.8%) of South African isolates were C. albicans (106 isolates), 9.4% were C. glabrata (12 isolates) and 7.8% were C. dubliniensis (10 isolates). Of the Cameroonian isolates, 73.02% were C. albicans (92 isolates); 19.05% C. glabrata (24 isolates); 3.2% C. tropicalis (4 isolates); 2.4% C. krusei (3 isolates); 1.59% either C. kefyr, C. parapsilopsis or C. lusitaneae (2 isolates); and 0.79% C. dubliniensis (1 isolate). Widespread C. albicans resistance to azoles was detected phenotypically in both populations. Differences in drug resistance were seen within C. glabrata found in both populations. Echinocandin drugs were more effective on isolates obtained from the Cameroon than in South Africa. A multiple drug resistant (MDR) C. dubliniensis strain isolated from the South African samples was inhibited only by 5-flucytosine in vitro on the YO9 panel. Drug resistance among oral Candida species is common among African HIV patients in these two countries. Regional surveillance of Candida species drug susceptibility should be undertaken to ensure effective treatment for HIV-positive patients.Item Proteomic mechanisms of drug resistance in Candida cell membrane fractions(International Association for Dental Research, 2014) Abrantes, Pedro Miguel dos Santos; Bouic, Patrick J.D.; Africa, Charlene W.J.INTRODUCTION: The African continent has the highest burden of HIV infection, accounting for approximately 65% of new infections globally. Oral candidiasis is a major cause of increased morbidity in HIV-infected individuals and is usually treated with fluconazole, an antifungal drug which interferes with ergosterol synthesis in the fungal cell membrane. The increased resistance of Candida species to antifungal drugs leads to treatment failure and an increase in untreatable Candida infections. OBJECTIVES/METHODS: Drug susceptibility patterns were determined for Candida species isolated from oral swabs of 254 patients from two HIV-positive African populations. Forty cell membrane fractions isolated from the clinical isolates were analyzed using High Performance Liquid Chromatography – Mass Spectrometry (HPLC-MS) and the results compared to the UniProt protein database for the identification of Candida peptides known to be involved in colonization and drug resistance strategies within the host. RESULTS: Fluconazole-susceptible and –resistant C. albicans isolates were found to express oxidoreductases that bind mammalian estrogens with high affinity. Peptides that confer resistance to formaldehyde were found in C. albicans, C. glabrata and C. dubliniensis in both susceptible and resistant cell fractions. Multidrug resistance proteins (CDR1 and CDR2) were seen in C. albicans cell fractions. CONCLUSION: The combination of different drug resistance mechanisms and binding abilities to salivary histatins and estrogen seem to be instrumental in the colonisation and retention of Candida in these immunocompromised patients. The results also suggest the presence of differences in efflux transporter protein expression in fluconazole-susceptible and –resistant isolates within the HIV population.Item 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.Item 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.Item 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 JoyceCandida 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.Item Real-time assessment of Candida biofilm formation(Elsevier, 2021-09) Abrantes, Pedro Miguel dos Santos; Behardien, Kauthar; Africa, Charlene Wilma JoyceBackground: 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.Item Strengths and limitations of different Chromogenic Media for the identification of Candida species(Scientific & Academic Publishing, 2012) Messeir, Ilze; Abrantes, Pedro Miguel dos Santos; Africa, Charlene W.J.The treatment of invasive candidiasis and other Candida infections with the appropriate antifungal agent is assisted by the identification of Candida isolates to the species level. Rapid and accurate methods of differentiation are therefore imperative if treatment is to be effective, particularly in HIV-positive patients and in pregnant mothers where intervention may be necessary to reduce the risk for preterm delivery. The time used for isolation, identification and detection of mixed cultures may be reduced with the help of available chromogenic media. In this study, five commercial chromogenic media were evaluated for the differentiation of Candida species. Six type-strains of Candida species were streaked onto each of five different chromogenic media and incubated for up to 4 days at the different temperatures recommended by the manufacturers. This comparative evaluation demonstrated the strengths and weaknesses of each medium employed and found CHROMagar™ Candida and Chromogenic Candida Agar to be the most effective for distinguishing between different Candida species.Item Vitek characterisation of type 2 diabetes-associated Candida species(Elsevier, 2017) Esmaio, Mustafa Hassan Mustafa; Abrantes, Pedro Miguel dos Santos; Africa, Charlene Wilma JoyceBackground: 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.