ABSTRACT
@#The purpose of this study is to characterize 3 non-albicans Candida spp. that were collected from two major hospitals in a densely populated area of Kuala Lumpur for their susceptibilities to azole and genetic background. Fifteen non-albicans Candida clinical isolates in two major hospitals in Kuala Lumpur area of Malaysia were collected by convenience sampling during 2007 and 2010. The genetic diversity of 15 non-albicans Candida species comprising C. glabrata (n = 5), C. parapsilosis (n = 5) and C. rugosa (n = 5) were assessed by RAPD-PCR typing. Strains were initially identified using biochemical tests and CHROMagar Candida medium. Fluconazole and voriconazole susceptibilities were determined by E-test method. Commercial kits were used for DNA extraction and amplification with RAPD primers (OPA02, OPA03 and OPA08). PCR conditions were optimized and simultaneous identification was possible by agarose gel electrophoresis of PCR products and the bands obtained were analyzed using BioNumerics Applied Maths v.6.6 software. The RAPD primers used in this study generated 100% polymorphic profile. Cluster analysis using the RAPD-PCR profile showed 12.5-25% similarity among the strains. The genetic diversity was based on the strain susceptibility towards both the azoles, site of isolation and place according to their unique banding patterns. In contrast, strains susceptible to azoles were found to be genetically similar with clonal dissimilarity. The use of OPA02, OPA03 and OPA08 primers in differentiating non-albicans Candida spp. underscores the higher resolution of RAPD-PCR as a reliable tool for strain/species level differentiation.
ABSTRACT
@#Candida species are the most common cause of fungal infections that range from non-life-threatening mucocutaneous illness to life-threatening invasive processes that may involve virtually any organ. Such a broad range of infections requires an equally broad range of therapeutic approach. Persian shallot (Allium stipitatum Regel.) is a medicinal plant that has been widely used in tradition Persian medicine for various ailments. Allium stipitatum is also used in modern medicine and has been reported to have a range of health benefits including antibiotic (antifungal) properties. The present study assessed the in vitro anticandidal and antibiofilm potential of hexane (ASHE) and dichloromethane (ASDE) extracts of Allium stipitatum (Persian shallot) against planktonic and biofilm forms of 5 medically important Candida spp. Antifungal activity was assessed by disk diffusion, minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC) and time-kill assay. The antibiofilm activity of ASHE and ASDE against reference strain C. albicans ATCC 14053 was determined by XTT [2,3-bis(2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide] reduction assay. The zone of inhibition ranged from 22 to 40 mm, while the MICs ranged from 8 to 32 μg mL-1. The MFCs of ASHE and ASDE were in the range of 16 to 32 μg mL-1 each respectively. Time-kill kinetics showed that both extracts were strongly fungicidal against planktonic cultures of C. albicans with ~ 1.45 log reduction in CFU at 4 h post-treatment (hpt). In addition, both ASHE and ASDE were shown to inhibit preformed C. albicans biofilms in a concentration-dependent manner. The results demonstrated that ASHE and ASDE were broad-spectrum in action, and could be developed as a promising alternative to synthetic antifungals in controlling infections due to Candida spp. of clinical significance.
ABSTRACT
The in vitro activities of 6 antimicrobial agents against clinical isolates of Streptococcus pneumoniae (pneumococci) were investigated and the erythromycin minimum inhibitory concentrations (MICs) were correlated with the two major macrolide resistance determinants, mef(A) and erm(B). MICs of commonly used antibiotics as well as the presence of macrolide resistance determinant genes in all isolates were tested. Seventy one pneumococcal isolates collected at Institute for Medical Research (IMR) were included in this study. Phenotypic characterization, MIC determination using E-test strips and polymerase chain reactions for antibiotic resistance determination were included. Among the isolates, 25 (35.2%) isolates were erythromycin susceptible, 3 (4.2%) were intermediate and 42 (60.6%) were resistant. Fifty three isolates (74.7%) were found with mef(A) alone, 15 (21.1%) isolates with erm(B) + mef(A) combination and 3 (4.2%) isolates with none of the two genes. The in vitro activity of penicillin, amoxicillin clavulanic acid, ceftriaxone and cefotaxime is superior to trimethoprim-sulfamethoxazole and erythromycin. In conclusion, pneumococcal isolates in this study were highly susceptible to penicillin with very low MICs. However, a very high prevalence rate of erythromycin resistance was observed. Erythromycin resistant S.pneumoniae isolates with both mef(A) and erm(B) showed very high MICs ≥256 μg/mL.