ORCID Profile
0000-0001-8557-5185
Current Organisations
University of Malaya
,
Universiti Malaya Nanotechnology and Catalysis Research Centre
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Publisher: American Society for Microbiology
Date: 15-12-2012
DOI: 10.1128/JB.01832-12
Abstract: The genome sequence analysis of a clinical Vibrio cholerae VC35 strain from an outbreak case in Malaysia indicates multiple genes involved in host adaptation and a novel Na + -driven multidrug efflux pump-coding gene in the genome of Vibrio cholerae with the highest similarity to VMA_001754 of Vibrio mimicus VMA223.
Publisher: Springer Science and Business Media LLC
Date: 20-11-2014
DOI: 10.1186/1471-2164-15-1007
Abstract: Typhoid fever is an infectious disease of global importance that is caused by Salmonella enterica subsp. enterica serovar Typhi ( S . Typhi). This disease causes an estimated 200,000 deaths per year and remains a serious global health threat. S . Typhi is strictly a human pathogen, and some recovered in iduals become long-term carriers who continue to shed the bacteria in their faeces, thus becoming main reservoirs of infection. A comparative genomics analysis combined with a phylogenomic analysis revealed that the strains from the outbreak and carrier were closely related with microvariations and possibly derived from a common ancestor. Additionally, the comparative genomics analysis with all of the other completely sequenced S . Typhi genomes revealed that strains BL196 and CR0044 exhibit unusual genomic variations despite S . Typhi being generally regarded as highly clonal. The two genomes shared distinct chromosomal architectures and uncommon genome features notably, the presence of a ~10 kb novel genomic island containing uncharacterised virulence-related genes, and zot in particular. Variations were also detected in the T6SS system and genes that were related to SPI-10, insertion sequences, CRISPRs and nsSNPs among the studied genomes. Interestingly, the carrier strain CR0044 harboured far more genetic polymorphisms (83% mutant nsSNPs) compared with the closely related BL196 outbreak strain. Notably, the two highly related virulence-determinant genes, rpoS and tviE , were mutated in strains BL196 and CR0044, respectively, which revealed that the mutation in rpoS is stabilising, while that in tviE is destabilising. These microvariations provide novel insight into the optimisation of genes by the pathogens. However, the sporadic strain was found to be far more conserved compared with the others. The uncommon genomic variations in the two closely related BL196 and CR0044 strains suggests that S . Typhi is more erse than previously thought. Our study has demonstrated that the pathogen is continually acquiring new genes through horizontal gene transfer in the process of host adaptation, providing novel insight into its unusual genomic dynamics. The understanding of these strains and virulence factors, and particularly the strain that is associated with the large outbreak and the less studied asymptomatic Typhi carrier in the population, will have important impact on disease control.
Publisher: Springer Science and Business Media LLC
Date: 13-06-2018
Publisher: Elsevier BV
Date: 06-2011
DOI: 10.1016/J.JIPH.2011.03.003
Abstract: Salmonella infections remain a major public health problem in developing countries. The occurrence of infections caused by antimicrobial-resistant Salmonella has been on the rise complicating the available therapeutic options. The study aimed to determine the antibiograms and genotypes of prevalent Salmonella serotypes. A retrospective study involving 80 stool and extra-intestinal Salmonella strains collected over a 18-month period (January 2005-June 2006) from a tertiary hospital in Penang, Malaysia was conducted. Isolates were examined for resistance to 14 antimicrobial drugs and the clonality of the strains was determined by PFGE. Twenty-one serotypes were identified, the most common being S. enteritidis (42.5%) followed by S. corvallis (11.25%) and S. braenderup (11.25%). S. enteritidis was significantly more common amongst the extra-intestinal isolates compared to stool isolates (74.2% versus 22.4%, p<0.0001). Overall, the highest resistance was observed for tetracycline (66.3%), sulphonamides (56.3%), streptomycin (32.5%), trimethoprim (28.8%) and nalidixic acid (27.5%). Amongst the 31 invasive extra-intestinal isolates, resistance towards therapeutically relevant antibiotics was as follows: co-trimoxazole (38.7%), icillin (29%) and ceftriaxone (3.2%). Although there was no detectable resistance towards chlor henicol and ciprofloxacin, 29% strains showed nalidixic acid resistance. About 41% of the 80 isolates were multidrug-resistant. PFGE subtyped the 78 Salmonella isolates to 33 distinct XbaI-pulsotypes. Isolates within the serotypes S. enteritidis, S. corvallis, S. branderup and S. fasta were more homogeneous while S. typhi and S. weltervden were genetically more erse. The high percentage of multidrug-resistant Salmonella strains is worrying and is of public health concern. PFGE was a useful and discriminative method for assessing the genetic ersity of Salmonellae.
Publisher: American Society for Microbiology
Date: 11-2012
DOI: 10.1128/JB.01466-12
Abstract: Acinetobacter baumannii is a major cause of nosocomial infection worldwide. We report the draft genome sequence of A. baumannii AC12, a multidrug-resistant nosocomial strain with additional resistance to carbapenems and polymyxin. The genome data will provide insights into the genetic basis of antimicrobial resistance and its adaptive mechanism.
Publisher: Springer Science and Business Media LLC
Date: 25-10-2012
Publisher: American Society for Microbiology
Date: 11-2012
DOI: 10.1128/JB.01416-12
Abstract: Salmonella enterica serovar Typhi is a human pathogen that causes typhoid fever predominantly in developing countries. In this article, we describe the whole genome sequence of the S. Typhi strain CR0044 isolated from a typhoid fever carrier in Kelantan, Malaysia. These data will further enhance the understanding of its host persistence and adaptive mechanism.
Publisher: MDPI AG
Date: 05-03-2015
DOI: 10.3390/S150305376
Abstract: In recent years, many improvements have been made in foodborne pathogen detection methods to reduce the impact of food contamination. Several rapid methods have been developed with biosensor devices to improve the way of performing pathogen detection. This paper presents an automated endpoint detection system for licons generated by loop mediated isothermal lification (LAMP) on a microfluidic compact disk platform. The developed detection system utilizes a monochromatic ultraviolet (UV) emitter for excitation of fluorescent labeled LAMP licons and a color sensor to detect the emitted florescence from target. Then it processes the sensor output and displays the detection results on liquid crystal display (LCD). The sensitivity test has been performed with detection limit up to 2.5 × 10−3 ng/µL with different DNA concentrations of Salmonella bacteria. This system allows a rapid and automatic endpoint detection which could lead to the development of a point-of-care diagnosis device for foodborne pathogens detection in a resource-limited environment.
Publisher: Elsevier BV
Date: 02-2015
DOI: 10.1016/J.IJANTIMICAG.2014.10.015
Abstract: Acinetobacter baumannii has emerged as an important nosocomial pathogen owing to its increasing resistance to most, if not all, antibiotics in clinical use. We recently reported the occurrence of extensively drug-resistant (XDR) A. baumannii isolates in a Malaysian tertiary hospital. The genome of one of these XDR isolates (A. baumannii AC12) was completely sequenced and comparative genome analyses were performed to elucidate the genetic basis of its antimicrobial resistance. The A. baumannii AC12 genome consists of a 3.8 Mbp circular chromosome and an 8731 bp cryptic plasmid, pAC12. It belongs to the ST195 lineage and is most closely related to A. baumannii BJAB0715 as well as other strains of the international clone III (IC-III) group. Two antibiotic resistance islands (RIs), designated AC12-RI1 and AC12-RI2, were found in the AC12 chromosome along with a 7 kb Tn1548::armA island conferring resistance to aminoglycosides and macrolides. The 22.8 kb AC12-RI1 interrupts the comM gene and harbours the carbapenem resistance gene blaOXA-23 flanked by ISAba1 within a Tn2006-like structure. AC12-RI1 also harbours resistance determinants for aminoglycosides, tetracyclines and sulphonamides. The 10.3 kb IS26-flanked AC12-RI2 is a derivative of AbGRI2-1, containing aphA1b and blaTEM genes (conferring aminoglycoside and β-lactam resistance, respectively). The presence of numerous genes mediating resistance to various antibiotics in novel RI structures as well as other genes encoding drug transporters and efflux pumps in A. baumannii AC12 most likely contributed to its XDR characteristics.
Publisher: Ivyspring International Publisher
Date: 2013
DOI: 10.7150/IJMS.6884
Publisher: Asian Pacific Organization for Cancer Prevention
Date: 06-11-2014
DOI: 10.7314/APJCP.2014.15.20.8957
Abstract: Promoter hypermethylation leads to altered gene functions and may result in malignant cellular transformation. Thus, identification of biomarkers for hypermethylated genes could be useful for diagnosis, prognosis, and therapeutic treatment of oral squamous cell carcinoma (OSCC). To screen hypermethylated genes with a microarray approach and to validate selected hypermethylated genes with the methylation-specific polymerase chain reaction (MSPCR). Genome-wide analysis of normal oral mucosa and OSCC tissues was conducted using the Illumina methylation microarray. The specified differential genes were selected and hypermethylation status was further verified with an independent cohort s le of OSCC s les. Candidate genes were screened using microarray assay and run by MSPCR analysis. TP73, PIK3R5, and CELSR3 demonstrated high percentages of differential hypermethylation status. Our microarray screening and MSPCR approaches revealed that the signature candidates of differentially hypermethylated genes may possibly become potential biomarkers which would be useful for diagnostic, prognostic and therapeutic targets of OSCC in the near future.
Publisher: American Society for Microbiology
Date: 11-2003
DOI: 10.1128/CDLI.10.6.1078-1084.2003
Abstract: The capsular polysaccharide Vi antigen (ViCPS) is an essential virulence factor and also a protective antigen of Salmonella enterica serovar Typhi. A random 12-mer phage-displayed peptide library was used to identify mimotopes (epitope analogues) of this antigen by panning against a ViCPS-specific monoclonal antibody (MAb) ATVi. Approximately 75% of the phage clones selected in the fourth round carried the peptide sequence TSHHDSHGLHRV, and the rest of the clones harbored ENHSPVNIAHKL and other related sequences. These two sequences were also obtained in a similar panning process by using pooled sera from patients with a confirmed diagnosis of typhoid fever, suggesting they mimic immunodominant epitopes of ViCPS antigens. Binding of MAb ATVi to the mimotopes was specifically blocked by ViCPS, indicating that they interact with the same binding site (paratope) of the MAb. Data and reagents generated in this study have important implications for the development of peptide-base diagnostic tests and peptide vaccines and may also provide a better understanding of the pathogenesis of typhoid fever.
Location: Malaysia
No related grants have been discovered for Kwai Lin Thong.