1.Identification of local clinical Candida isolates using CHROMagar CandidaTM as a primary identification method for various Candida species
Madhavan, P.* ; Jamal, F. ; Chong, P.P. ; Ng, K.P.
Tropical Biomedicine 2011;28(2):269-274
The objective of our study was to study the effectiveness of CHROMagar CandidaTM
as the primary identification method for various clinical Candida isolates, other than the
three suggested species by the manufacturer. We studied 34 clinical isolates which were
isolated from patients in a local teaching hospital and 7 ATCC strains. These strains were first
cultured in Sabouraud dextrose broth (SDB) for 36 hours at 35ºC, then on CHROMagar plates
at 30ºC, 35ºC and 37ºC. The sensitivity of this agar to identify Candida albicans, Candida
dubliniensis, Candida tropicalis, Candida glabrata, Candida rugosa, Candida krusei and
Candida parapsilosis ranged between 25 and 100% at 30ºC, 14% and 100% at 35ºC, 56% and
100% at 37ºC. The specificity of this agar was 100% at 30ºC, between 97% and 100% at 35ºC,
92% and 100% at 37ºC. The efficiency of this agar ranged between 88 and 100% at 30ºC, 83%
and 100% at 35ºC, 88% and 100% at 37ºC. Each species also gave rise to a variety of colony
colours ranging from pink to green to blue of different colony characteristics. Therefore, the
chromogenic agar was found to be useful in our study for identifying clinical Candida isolates
2.Comparison of Anyplex II RV16 assay with conventional methods for detection of respiratory viruses
Kuan, C.S., Hooi, P.S., Lee, L.M., Sam, I.C. and Ng, K.P.
Tropical Biomedicine 2016;33(2):311-319
Early detection of viral etiologies of acute respiratory tract infections of patients
affects management and disease control in pediatric patients. In this study, the performance
of Anyplex II RV16 assay (Seegene, Seoul, Korea) was evaluated by comparing with viral
culture and direct immunofluorescence staining of clinical specimens for detection of
respiratory viruses in patients. A total of 168 respiratory specimens were collected from 122
patients from November 2012 to May 2013 at the time of admission to the University of
Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia. The Anyplex II RV16 assay, viral
culture, and direct immunofluorescence staining were positive in 74.4%, 18.5% and 14.9% of
the specimens, respectively. HRV was the predominant virus detected by the Anyplex II RV16
assay. In 47 cases, two or more respiratory viruses were detected by the Anyplex II RV16
assay, which were missed by conventional methods. The performance of the Anyplex II RV16
assay was better than viral culture and direct immunofluorescence staining of clinical
specimens for the detection of respiratory viruses. The implementation of the Anyplex II
RV16 assay in hospital laboratories will provide rapid diagnosis of major viral infections of the
respiratory tract.
3.In vitro adhesion and invasion by Cladosporium sphaerospermum in human bronchial epithelial cells (BEAS-2B) and human pulmonary alveolar epithelial cells (HPAEpiC)
Lo, S.G. ; Wong, S.F ; Mak, J.W. ; Choo, K.K. ; Ng, K.P.
Tropical Biomedicine 2019;36(4):958-971
Cladosporium spores are ubiquitous in indoor and outdoor environment and may
potentially trigger allergic responses upon inhalation. To date, there is limited investigation
on the fate of Cladosporium spores after being inhaled into the respiratory tract. This study
was conducted to investigate the interaction of Cladosporium sphaerospermum with Human
Bronchial Epithelial Cells (BEAS-2B) and Human Pulmonary Alveolar Epithelial Cells
(HPAEpiC). C. sphaerospermum conidia were harvested and co-cultured with BEAS-2B or
HPAEpiC cells for 72 hours. At each time point (30 minutes, 2, 4, 24, 48 and 72 hours),
adherence and invasion of the cells by C. sphaerospermum conidia (and hyphae) were
investigated by immunofluorescence staining. This study demonstrated the adherence and
internalization of C. sphaerospermum conidia within these epithelial cells. In addition, the
conidia were able to germinate and invade the epithelial cells. The ability of the fungal
conidia to adhere, internalize, germinate and invade both the bronchial and alveolar epithelial
cells of the respiratory tract in vitro might contribute to the understanding of the pathogenesis
of Cladosporium in respiratory infection and allergy in vivo.
INTRODUCTION
Cladosporium species is a member of the
phylum Ascomycota. The common species
include C. herbarum, C. cladosporioides
and C. sphaerospermum. This genus has
worldwide distribution. Aerobiological
studies reported that majority of fungal
spores in outdoor air is from the phyla
Ascomycota and Basidiomycota, while
Cladosporium is one of the most studied
allergenic Ascomycetes fungi (Knutsen et
al., 2012). Cladosporium spores are found
abundantly in indoors and outdoors at
approximately 18/m3 and 141/m3 respectively
(Codina et al., 2008).
As an imperfect dematiaceous fungus,
Cladosporium species causes opportunistic
infections such
4.Genetic diversity, antifungal susceptibility and enzymatic characterisation of Malaysian clinical isolates of Candida glabrata
Lotfalikhani, A. ; Khosravi, Y. ; Sabet, N.S. ; Na, S.L. ; Ng, K.P ; Tay, S.T.
Tropical Biomedicine 2018;35(4):1123-1130
Candida glabrata has been reported as the second or third most common yeast
species isolated from patients with vaginitis and invasive candidiasis. This study was aimed
to determine the genetic diversity, antifungal susceptibility and enzymatic profiles of C.
glabrata isolated from vaginal and blood samples in the Medical Microbiology Diagnostic
Laboratory, University Malaya Medical Centre. A random amplified polymorphic DNA (RAPD)
analysis method, using M13 and (GTG)5 primers, was used for strain differentiation of C.
glabrata isolates. Antifungal susceptibility testing of C. glabrata isolates was determined
using E-test against amphotericin B, caspofungin, fluconazole and voriconazole and microbroth
dilution method against clotrimazole. The enzymic profiles of C. glabrata were determined
using APIZYM semi-quantitation kit and egg-yolk agar method. A total of 14 RAPD patterns
were identified amongst C. glabrata isolates investigated this study. Susceptibility to
amphotericin B, caspofungin, fluconazole and voriconazole was noted. Approximately one
third of the isolates demonstrated resistance to clotrimazole (MIC>1 μg/ml). A single isolate
of C. glabrata was resistant to caspofungin (MIC:1.5 μg/ml). Enzymatic activities of acid and
alkaline phosphatase, aminopeptidases, esterase and lipase and phospholipase were detected
in the C. glabrata isolates. The genetic diversity and antifungal susceptibility profiles of C.
glabrata isolates were presented in this study. Continued surveillance and monitoring of the
incidence and antifungal resistance in C. glabrata isolates is necessary.
5.Antimicrobial susceptibilities and random amplified polymorphic DNA-PCR fingerprint characterization of Candida glabrata, Candida parapsilosis and Candida rugosa from two major hospitals in Kuala Lumpur, Malaysia
Madhavan, P. ; Chong, P.P ; Farida, J. ; Fauziah, O. ; Cheah, Y.K. ; Arunkumar Karunanidhi, A. ; Ng, K.P.
Tropical Biomedicine 2019;36(1):183-193
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.