Species distribution and antifungal susceptibility patterns of Candida isolates from a public tertiary teaching hospital in the Eastern Cape Province, South Africa

vital:49389Candida species are the leading cause of invasive fungal infections, and over the past decade there has been an increased isolation of drug resistant Candida species. This study aimed to identify the species distribution of Candida isolates and to determine their unique antifungal susceptibility and resistance patterns. During a cross-sectional study, 209 Candida isolates (recovered from 206 clinical samples) were collected and their species distribution was determined using ChromAgar Candida. The Vitek-2 system (Biomerieux, South Africa) was used to determine minimum inhibitory concentrations (MICs) to azoles (fluconazole, voriconazole), echinocandins (caspofungin, micafungin), polyenes (amphotericin B) and flucytosine. Four species of Candida were isolated, of which C. albicans was the most frequent, isolated in 45.4 percent (95/209) of the isolates, followed by C. glabrata: 31.1 percent (65/209). The MICs of the different antifungal drugs varied amongst the species of Candida. From the 130 isolates tested for MICs, 90.77 percent (112/130) were susceptible to all antifungal drugs and 6.9 percent (9/130) of the isolates were multi-drug resistant. C. dubliniensis (n=2) isolates were susceptible to all the above mentioned antifungal drugs. There was no significant difference in species distribution amongst clinical specimens and between patients’ genders (P40.05). An increase in MIC values for fluconazole and flucytosine towards the resistance range was observed. To our knowledge, this is the first report on surveillance of Candida species distribution and antifungal susceptibility at a public tertiary teaching hospital in Eastern Cape, South Africa. Key words: Candida species; Distribution; Antifungal susceptibility; Identification; South Afric

Polymer supported calix[4]arene-semicarbazone derivative for separation and preconcentration of La(III), Ce(III), Th(IV) and U(VI)

The new "upper-rim" functionalized 11,23-disemicarbazono-26,28-n-dipropoxy-25,27-dihydroxy calix[4]arene has been synthesized by condensing 11,23-diformyl-26,28-n-dipropoxy-25,27-dihydroxy calix[4]arene with semicarbazide hydrochloride. This calix[4]arene-semicarbazone derivative was then covalently linked with commercially available Merrifield's peptide resin at the "lower-rim" to obtain polymeric chelating resin and its analytical properties were investigated. The resin was then used successfully for the separation and preconcentration of lanthanum(III), cerium(III), thorium(IV) and uranium(VI) prior to their determination by spectrophotometry and inductively coupled plasma atomic emission spectroscopy. The resin exhibits good separating ability with maximum sorption between pH 2.5-4.5 for Th(IV) and between pH 5.5-7.0 for U(VI) whereas La(III) and Ce(III) were found to have maximum sorption between pH 6.5-8.5. The elution studies were carried out with 0.01 M HCl for La(III) and Ce(III), 2.0 M HCl for Th(IV) and 0.25 M HCl for U(VI). The preconcentration factors for La(III), Ce(III), Th(IV) and U(VI) were 125, 130, 102 and 108, respectively. The resin shows good stability along with faster rate of equilibrium for all the metal ions. The influence of several ions (cations and anions) on the resin performance is also discussed. The relative standard deviation was between 96 and 98% with good analytical reliability. The proposed method was applied for the determination of metal ions in monazite sand and some standard geological materials. © 2002 Elsevier Science B.V. All rights reserved

Pre-concentration, separation and trace determination of lanthanum(III), cerium(III), thorium(IV) and uranium(VI) on polymer supported o-vanillinsemicarbazone

A nonionic polymeric adsorbent styrene divinylbenzene, Amberlite XAD-4 was functionalized with o-vanillinsemicarbazone and its analytical properties have been studied. The synthesized resin was utilized for selective column separation, pre-concentration and trace determination of lanthanum(III) (La(III)), cerium(III) (Ce(III)), thorium(IV) (Th(III)) and uranium(VI) (U(VI)). The resin exhibits good chemical stability, reusability and faster rate of equilibrium for their determination by spectrophotometry and their simultaneous confirmation of the results by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and graphite furnace-atomic absorption spectrometry (GF-AAS). Both, the uptake and stripping of these metal ions were fairly rapid, indicating a better accessibility of the chelating sites. The proposed method has been applied to sequential chromatographic separation of their binary and ternary mixtures. Uranium(VI) has been determined from simulated river water sample with good analytical reliability. The detection limit of these metal ions on the resin is 100 ng cm-3 with recovery upto 96-98%. The method is also applied for their determination in monazite sand and some standard geological materials. © 2001 Published by Elsevier Science B.V