Conference Papers (Medical Bioscience)

Permanent URI for this collection

https://hdl.handle.net/10566/1741

Browse

Now showing 1 - 11 of 11

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.
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.
A comparison between the anthropological and modern day uses of this indigenous herb
(Conference: SA Medical Research Council 6th Annual Research Conference, 2012) Leisegang, Kristian; Campbell, James; Ma, X; De Beer, Sanien
Sceletium tortuosum (Fig. 1) is a scrambling succulent ground cover indigenous to the Western and Eastern Cape. It has probably been used for centuries as a mood-altering drug, especially by the Khoisan hunters and Nama shepherds, where it was often smoked or used as snuff. It also has hallucinogenic properties and high dosages were often used during trance dances. These properties have been associated with alkaloids such as mesembrine. The San people used it prior to hunting to sharpen their senses, and to diminish hunger and thirst. Even in excessive dosages its initial euphoric effect seems to be replaced with feelings of serene sedation. It was more often used for enjoyment and not primarily for medicine. Modern day medical and commercial use of Sceletium spp is primary as a mood enhancer, to decrease anxiety, stress, and in addiction therapy. The objectives of this study was to investigate and compare the historical and anthropological se of Sceletium with the modern day and current uses there of.
Maternal and Neonatal Group B Streptococcus colonisation in a cohort of Libyan women
(2021-01-18) Elmahaishi, Lubna M S; Abrantes, Pedro M D S; Africa, Charlene W J
Background: Group B streptococcus (GBS) may be vertically transmitted from mother to infant during labour and cause life threatening neonatal sepsis. The objective of this study was to determine the risk and prevalence of GBS colonisation and vertical transmission and to establish an association between GBS colonisation and pregnancy outcomes. Methods: One hundred samples were randomly collected from women at labour at Said hospital in Misrata, Libya. The study complied with the Declaration of Helsinki (2013). Maternal data was obtained through a questionnaire. Caesarean deliveries and women who had received antibiotic therapy within two weeks prior to sample collection were excluded from the study. Vaginal and rectal swabs were collected from each patient using sterile cotton-tipped swabs. Infant swabs were collected from the external ear canal at birth. GBS was detected using the Agilent AriaMx Real-Time PCR System. Results: GBS was detected in 14 maternal rectal swabs and 12 vaginal swabs. GBS was detected in both vaginal and rectal swabs from only 8 mothers. Age, level of education, parity and gravidity showed no correlation with GBS colonisation nor pregnancy outcomes. Of the 100 mothers who participated in the study, 93% delivered full term, while 7% delivered preterm. Normal birth weight was observed in 74% of the neonates with a significant association observed between birth weight of the neonate and GBS colonisation and between preterm delivery and GBS colonisation. Conclusion: The prevalence of maternal GBS colonisation and risk for adverse pregnancy outcomes was low in this cohort of women, thus reducing the risk for neonatal sepsis.
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.
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.
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.
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.
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.
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.
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.

Browse

collection.page.browse.recent.head