Displaying publications 61 - 80 of 250 in total

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  1. Liew SM, Rajasekaram G, Puthucheary SD, Chua KH
    J Glob Antimicrob Resist, 2018 06;13:271-273.
    PMID: 29432937 DOI: 10.1016/j.jgar.2018.01.026
    OBJECTIVES: The increasing incidence of carbapenem-resistant Pseudomonas aeruginosa along with the discovery of novel metallo-β-lactamases (MBLs) is of concern. In this study, the isolation of MBL-producing P. aeruginosa clinical strains in Malaysia was investigated.

    METHODS: A total of 53 P. aeruginosa clinical strains were isolated from different patients in Sultanah Aminah Hospital (Johor Bahru, Malaysia) in 2015. Antimicrobial susceptibility testing was performed, and minimum inhibitory concentrations (MICs) of imipenem and meropenem were determined by Etest. Carbapenem-resistant strains were screened for MBL production by the imipenem-ethylene diamine tetra-acetic acid (IMP-EDTA) double-disk synergy test, MBL imipenem/imipenem-inhibitor (IP/IPI) Etest and PCR. Multilocus sequence typing (MLST) analysis was performed for genotyping of the isolates.

    RESULTS: Among the 53 clinical strains, 3 (5.7%) were identified as MBL-producers. Multidrug resistance was observed in all three strains, and two were resistant to all of the antimicrobials tested. Sequencing analysis confirmed that the three strains harboured carbapenemase genes (blaIMP-1, blaVIM-2 and blaNDM-1 in one isolate each). These multidrug-resistant strains were identified as sequence type 235 (ST235) and ST308.

    CONCLUSIONS: The blaIMP-1 and blaNDM-1 genes have not previously been reported in Malaysian P. aeruginosa isolates. The emergence of imipenemase 1 (IMP-1)- and New Delhi metallo-β-lactamase 1 (NDM-1)-producing P. aeruginosa in Malaysia maybe travel-associated.

  2. Thong KL, Teh CS, Chua KH
    Trop Biomed, 2014 Dec;31(4):689-97.
    PMID: 25776594 MyJurnal
    The present study aims to develop a system which consists of four pairs of primers that specifically detects Salmonella spp., Salmonella serovar Typhi and Salmonella serovar Paratyphi A with an internal amplification control. The system, when applied in Polymerase Chain Reaction (PCR) under specific conditions, reaction mixture and cycling temperatures produced four bands; 784 bp, 496 bp, 332 bp and 187 bp. The DNA band 784 bp is present in all Salmonella spp., while the bands of 496 bp and 332 bp are only present in S. Paratyphi A and S. Typhi, respectively. An internal amplification control as indicated by the 187 bp shows the system is working in optimum condition in all the tests. This multiplex PCR was evaluated on 241 bacterial cultures and 691 naturally contaminated samples. Overall, this multiplex PCR detection system provides a single step for simultaneous detection of DNAs of Salmonella spp., S. Typhi and S. Paratyphi A.
  3. Chua KH, See KH, Thong KL, Puthucheary SD
    Trop Biomed, 2010 Dec;27(3):517-24.
    PMID: 21399594 MyJurnal
    Melioidosis is an infectious disease caused by Burkholderia pseudomallei and endemic in Southeast Asia. One hundred and forty six clinical isolates of B. pseudomallei from different states in Malaysia were obtained and molecular typing was carried out using pulsed-field gel electrophoresis (PFGE). Overall, nine clusters were successfully identified. Burkholderia pseudomallei isolates used in this study were found to be genetically diverse and there were differences in the clusters of isolates from peninsular and east Malaysia. BS9 cluster was the most common cluster and found in all the states while BS2 cluster only existed in a particular state. Based on the PFGE analysis, the distribution of different B. pseudomallei clinical isolates in Malaysia was mapped.
  4. Thong KL, Lai MY, Teh C SJ, Chua KH
    Trop Biomed, 2011 Apr;28(1):21-31.
    PMID: 21602765 MyJurnal
    A PCR-based assay that can simultaneously detect and differentiate five different types of nosocomial bacterial pathogens was developed. Six pairs of selected primers targeting femA (132 bp) and mecA (310 bp) of methicillin-resistant Staphylococcus aureus, gltA (722 bp) of Acinetobacter baumannii, phoA (903 bp) of Escherichia coli, mdh (364 bp) of Klebsiella pneumoniae and oprL (504 bp) of Pseudomonas aeruginosa were used in this study. The conditions were optimized for the multiplex PCR to ensure specific amplification of the selected targets. Sensitivity and specificity tests were also carried out using a blind test approach on 50 bacterial cultures and resulted in 100% for both positive and negative predictive values.
  5. Lau MF, Chua KH, Sabaratnam V, Kuppusamy UR
    Biotechnol Appl Biochem, 2021 Aug;68(4):902-917.
    PMID: 32856730 DOI: 10.1002/bab.2013
    Ganoderma neo-japonicum is a well-known medicinal mushroom in Asian countries. However, scientific validations on its curative activities are confined to cirrhosis and diabetes. In this study, the anticancer properties of G. neo-japonicum were evaluated using cellular and computational models. The ethanolic extract (EtOH) with a promising inhibitory effect was fractionated into four different fractions: hexane (Hex), chloroform (Chl), butanol (Btn), and aqueous (Aq). The active fractions were then subjected to cell apoptosis assessment and phytochemical profiling. Molecular docking was conducted to elucidate the affinity of selected constituents towards antiapoptotic Bcl-2 protein. The butanol fraction showed the highest antioxidant activities as well as total phenolic content. Both hexane and chloroform fractions exerted a potent cytotoxic effect on colonic carcinoma cells through the induction of apoptosis. Phytochemical analysis revealed that the chloroform fraction is terpenoid enriched whereas the hexane fraction comprises predominantly sterol constituents. Stellasterol and 1,25-dihydroxyvitamin D3 3-glycoside were demonstrated to have a high affinity towards Bcl-2 protein. Overall, G. neo-japonicum can be considered as a compelling therapeutic candidate for cancer treatment.
  6. Puah SM, Tan JAMA, Chew CH, Chua KH
    J Food Sci, 2018 Sep;83(9):2337-2342.
    PMID: 30101982 DOI: 10.1111/1750-3841.14300
    Staphylococcus aureus is able to form multilayer biofilms embedded within a glycocalyx or slime layer. Biofilm formation poses food contamination risks and can subsequently increase the risk of food poisoning. Identification of food-related S. aureus strains will provide additional data on staphylococcal food poisoning involved in biofilm formation. A total of 52 S. aureus strains isolated from sushi and sashimi was investigated to study their ability for biofilm formation using crystal violet staining. The presence of accessory gene regulator (agr) groups and 15 adhesion genes was screened and their associations in biofilm formation were studied. All 52 S. aureus strains showed biofilm production on the tested hydrophobic surface with 44% (23/52) strains classified as strong, 33% (17/52) as moderate, and 23% (12/52) as weak biofilm producers. The frequency of agr-positive strains was 71% (agr group 1 = 21 strains; agr group 2 = 2 strains; agr group 3 = 12 strains; agr group 4 = 2 strains) whereas agr-negative strains were 29% (15/52). Twelve adhesion genes were detected and 98% of the S. aureus strains carried at least one adhesion gene. The ebps was significantly (p < .05) associated with strong biofilm producing strains. In addition, eno, clfA, icaAD, sasG, fnbB, cna, and sasC were significantly higher in the agr-positive group compared to the agr-negative group. The results of this study suggest that the presence of ebps, eno, clfA, icaAD, sasG, fnbB, cna, and sasC may play an important role in enhancing the stage of biofilm-related infections and warrants further investigation.

    PRACTICAL APPLICATION: This work contributes to the knowledge on the biofilm formation and the distribution of agr groups in S. aureus strains as well as microbial surface components in recognizing adherence matrix molecules of organisms isolated from ready-to-eat sushi and sashimi. The findings provide valuable information to further study the roles of specific genes in causing biofilm-related infections.

  7. Liew SM, Rajasekaram G, Puthucheary SA, Chua KH
    PeerJ, 2019;7:e6217.
    PMID: 30697478 DOI: 10.7717/peerj.6217
    Background: Pseudomonas aeruginosa is ubiquitous, has intrinsic antibiotic resistance mechanisms, and is associated with serious hospital-associated infections. It has evolved from being a burn wound infection into a major nosocomial threat. In this study, we compared and correlated the antimicrobial resistance, virulence traits and clonal relatedness between clinical and fresh water environmental isolates of P. aeruginosa.

    Methods: 219 P. aeruginosa isolates were studied: (a) 105 clinical isolates from 1977 to 1985 (n = 52) and 2015 (n = 53), and (b) 114 environmental isolates from different fresh water sources. All isolates were subjected to ERIC-PCR typing, antimicrobial susceptibility testing and virulence factor genes screening.

    Results: Clinical and environmental isolates of P. aeruginosa were genetically heterogenous, with only four clinical isolates showing 100% identical ERIC-PCR patterns to seven environmental isolates. Most of the clinical and environmental isolates were sensitive to almost all of the antipseudomonal drugs, except for ticarcillin/clavulanic acid. Increased resistant isolates was seen in 2015 compared to that of the archived isolates; four MDR strains were detected and all were retrieved in 2015. All clinical isolates retrieved from 1977 to 1985 were susceptible to ceftazidime and ciprofloxacin; but in comparison, the clinical isolates recovered in 2015 exhibited 9.4% resistance to ceftazidime and 5.7% to ciprofloxacin; a rise in resistance to imipenem (3.8% to 7.5%), piperacillin (9.6% to 11.3%) and amikacin (1.9% to 5.7%) and a slight drop in resistance rates to piperacillin/tazobactam (7.7% to 7.5%), ticarcillin/clavulanic acid (19.2% to 18.9%), meropenem (15.4% to 7.5%), doripenem (11.5% to 7.5%), gentamicin (7.7% to 7.5%) and netilmicin (7.7% to 7.5%). Environmental isolates were resistant to piperacillin/tazobactam (1.8%), ciprofloxacin (1.8%), piperacillin (4.4%) and carbapenems (doripenem 11.4%, meropenem 8.8% and imipenem 2.6%). Both clinical and environmental isolates showed high prevalence of virulence factor genes, but none were detected in 10 (9.5%) clinical and 18 (15.8%) environmental isolates. The exoT gene was not detected in any of the clinical isolates. Resistance to carbapenems (meropenem, doripenem and imipenem), β-lactamase inhibitors (ticarcillin/clavulanic acid and piperacillin/tazobactam), piperacillin, ceftazidime and ciprofloxacin was observed in some of the isolates without virulence factor genes. Five virulence-negative isolates were susceptible to all of the antimicrobials. Only one MDR strain harbored none of the virulence factor genes.

    Conclusion: Over a period of 30 years, a rise in antipseudomonal drug resistance particularly to ceftazidime and ciprofloxacin was observed in two hospitals in Malaysia. The occurrence of resistant environmental isolates from densely populated areas is relevant and gives rise to collective anxiety to the community at large.

  8. Mohd Heikal MY, Ahmad Nazrun S, Chua KH, Norzana AG
    Cytotechnology, 2019 Apr;71(2):521-537.
    PMID: 30719603 DOI: 10.1007/s10616-019-00298-2
    The proinflammatory cytokines, metalloproteinases family (MMPs), inflammatory mediators PGE2, COX-2 and NO are the most important group of compounds responsible for the loss of metabolic homeostasis of articular cartilage by promoting catabolic and destructive processes in the pathogenesis of osteoarthritis (OA). Stichopus chloronotus, a marine sea cucumber which is rich in n-3 PUFAs and phenolic compound, may exert a favorable influence on the course of the disease. The objective of this study was to investigate the regeneration and anti-inflammatory potential of S. chloronotus aqueous extract (SCAE) on human OA articular chondrocytes (HOC).

    METHODS: The HOC isolated from knee joint cartilage removed during surgery were cultured with SCAE for 7 days. The effect of SCAE on anabolic and catabolic gene expression was verified by real-time PCR. Monolayer chondrocytes were stained with toluidine blue whereas sGAG, NO and PGE2 production in medium were analyzed by ELISA.

    RESULTS: The HOC cultured in various SCAE have polygonal morphology maintaining their chondrocytes characteristic. SAE supplementation tested was found to be effective pro-chondrogenic, anti-inflammatory and anti-oxidative agents, as evidenced by upregulation of cartilage specific markers collagen type II, aggrecan core protein and sox-9 expression and downregulation of collagen type 1, IL-1, IL-6, IL-8, MMP-1, MMP-3, MMP-13, COX-2, iNOS and PAR-2 expression. The presence of SCAE in the culture was able to increase sGAG and reduce NO and PGE2 production significantly.

    CONCLUSIONS: These results suggested that SCAE demonstrated chondroprotective ability by suppressing catabolic activities, oxidative damage and effectively promoting chondrocytes growth.

  9. Kee BP, Chua KH, Lee PC, Lian LH
    Ann Hum Biol, 2012 Nov-Dec;39(6):505-10.
    PMID: 22989108 DOI: 10.3109/03014460.2012.719548
    The present study is the first to report the genetic relatedness of indigenous populations of Sabah, Malaysia, using a set of Indel markers (HS4.32, TPA25, APO, PV92, B65 and HS3.23). The primary aim was to assess the genetic relationships among these populations and with populations from other parts of the world by examining the distribution of these markers.
  10. Puah SM, Puthucheary SDA, Chua KH
    Jpn J Infect Dis, 2022 Jan 31.
    PMID: 35095023 DOI: 10.7883/yoken.JJID.2021.477
    Genus Plesiomonas, represented by a single species, P. shigelloides is a Gram-negative bacillus associated with gastrointestinal and extraintestinal disease in humans. In this study, 44 clinical isolates (gastrointestinal n=41; extraintestinal n=3) were genetically confirmed as P. shigelloides using the hug gene. All 20 virulence genes were detected in gastrointestinal isolates, ranging from 7.7% to 100%, however, only 12 genes were detected in extra-gastrointestinal isolates, ranging from 33.3% to 100%. The phlA gene was significantly (p=0.0216) associated with gastrointestinal isolates. The results of this study suggest that the presence of phlA may play a role in gastrointestinal-related infections. On the other hand, pilF, tolC and fur were detected in both gastrointestinal and extraintestinal clinical isolates and further investigations are warrants to elucidate their role in the pathogenesis of P. shigelloides.
  11. Chew CH, Lim YAL, Chua KH
    PeerJ, 2017;5:e3794.
    PMID: 28929019 DOI: 10.7717/peerj.3794
    BACKGROUND: Plasmodium is an obligate intracellular parasite. Apical membrane antigen 1 (AMA1) is the most prominent and well characterized malarial surface antigen that is essential for parasite-host cell invasion, i.e., for sporozoite to invade and replicate within hepatocytes in the liver stage and merozoite to penetrate and replicate within erythrocytes in the blood stage. AMA1 has long served as a potent antimalarial drug target and is a pivotal vaccine candidate. A good understanding of the structure and molecular function of this Plasmodium protein, particularly its involvement in host-cell adhesion and invasion, is of great interest and hence it offers an attractive target for the development of novel therapeutics. The present study aims to heterologous express recombinant Plasmodium AMA1 ectodomain of P. vivax (rPvAMA1) for the selection of binding peptides.

    METHODS: The rPvAMA1 protein was heterologous expressed using a tag-free Profinity eXact(TM) system and codon optimized BL21-Codon Plus (DE3)-RIL Escherichia coli strain and further refolded by dialysis for renaturation. Binding peptides toward refolded rPvAMA1 were panned using a Ph.D.-12 random phage display library.

    RESULTS: The rPvAMA1 was successfully expressed and refolded with three phage-displayed dodecapeptides designated as PdV1 (DLTFTVNPLSKA), PdV2 (WHWSWWNPNQLT), and PdV3 (TSVSYINNRHNL) with affinity towards rPvAMA1 identified. All of them exhibited positive binding signal to rPvAMA1 in both direct phage assays, i.e., phage ELISA binding assay and Western blot binding assay.

    DISCUSSION: Phage display technology enables the mapping of protein-protein interactions based on a simple principle that a library of phage particles displaying peptides is used and the phage clones that bind to the target protein are selected and identified. The binding sites of each selected peptides toward PvAMA1 (Protein Data Bank, PDB ID: 1W8K) were in silico predicted using CABS-dock web server. In this case, the binding peptides provide a valuable starting point for the development of peptidomimetic as antimalarial antagonists directed at PvAMA1.

  12. Chua KH, Aminuddin BS, Fuzina NH, Ruszymah BH
    Singapore Med J, 2007 Apr;48(4):324-32.
    PMID: 17384880
    The objectives of this study were to determine the optimum concentration of basic fibroblast growth factor (bFGF) in foetal bovine serum (FBS) or human serum (HS) supplemented medium for adult human nasal septum chondrocyte culture and to evaluate the potential of cartilage regeneration.
  13. Chua KB, Chua IL, Chua IE, Chua KH
    Singapore Med J, 2005 Nov;46(11):639-44.
    PMID: 16228097
    Dengue and dengue haemorrhagic fever are common and serious arboviral diseases endemic in a number of countries situated in both the tropical and subtropical belts.
  14. Lau MF, Chua KH, Sabaratnam V, Kuppusamy UR
    Sci Prog, 2020;103(1):36850419886448.
    PMID: 31795844 DOI: 10.1177/0036850419886448
    Colorectal cancer is one of the most prevalent noncommunicable diseases worldwide. 5-Fluorouracil is the mainstay of chemotherapy for colorectal cancer. Previously, we have demonstrated that high glucose diminishes the cytotoxicity of 5-fluorouracil by promoting cell cycle progression. The synergistic impact of rosiglitazone on 5-fluorouracil-induced apoptosis was further investigated in this study. Besides control cell lines (CCD-18Co), two human colonic carcinoma cell lines (HCT 116 and HT 29) were exposed to different treatments containing 5-fluorouracil, rosiglitazone or 5-fluorouracil/rosiglitazone combination under normal glucose (5.5 mM) and high-glucose (25 mM) conditions. The cellular oxidative stress level was evaluated with biomarkers of nitric oxide, advanced oxidation protein products, and reduced glutathione. The cell apoptosis was assessed using flow cytometry technique. High glucose caused the production of reduced glutathione in HCT 116 and HT 29 cells. Correspondingly, high glucose suppressed the apoptotic effect of 5-fluorouracil and rosiglitazone. As compared to 5-fluorouracil alone (2 µg/mL), addition of rosiglitazone significantly enhanced the apoptosis (increment rate of 5-20%) in a dose-dependent manner at normal glucose and high glucose levels. This study indicates that high-glucose-induced reduced glutathione confers resistance to apoptosis, but it can be overcome upon treatment of 5-fluorouracil and 5-fluorouracil/rosiglitazone combination. Rosiglitazone may be a promising antidiabetic drug to reduce the chemotherapeutic dose of 5-fluorouracil for colorectal cancer complicated with hyperglycemia.
  15. Liau LL, Makpol S, Azurah AGN, Chua KH
    Cytotechnology, 2018 Aug;70(4):1221-1233.
    PMID: 29549558 DOI: 10.1007/s10616-018-0214-8
    Currently, orthotopic liver transplantation is the gold standard therapy for liver failure. However, it is limited by the insufficient organ donor and risk of immune rejection. Stem cell therapy is a promising alternative treatment for liver failure. One of the most ideal sources of stem cells for regenerative medicine is adipose-derived stem cells (ADSCs). In this study, primary ADSCs seeded on cell culture insert were indirectly co-cultured with injured HepG2 to elucidate the role of ADSCs in promoting the recovery of injured HepG2 in non-contact manner. HepG2 recovery was determined by the surface area covered by cells and growth factor concentration was measured to identify the factors involved in regeneration. Besides, HepG2 were collected for q-PCR analysis of injury, hepatocyte functional and regenerative markers expression. For the ADSCs, expression of hepatogenic differentiation genes was analyzed. Results showed that non-contact co-culture with ADSCs helped the recovery of injured HepG2. ELISA quantification revealed that ADSCs secreted higher amount of HGF and VEGF to help the recovery of injured HepG2. Furthermore, HepG2 co-cultured with ADSCs expressed significantly lower injury markers as well as significantly higher regenerative and functional markers compared to the control HepG2. ADSCs co-cultured with injured HepG2 expressed significantly higher hepatic related genes compared to the control ADSCs. In conclusion, ADSCs promote recovery of injured HepG2 via secretion of HGF and VEGF. In addition, co-cultured ADSCs showed early sign of hepatogenic differentiation in response to the factors released or secreted by the injured HepG2.
  16. Arumugam B, Palanisamy UD, Chua KH, Kuppusamy UR
    Mol Vis, 2019;25:47-59.
    PMID: 30820141
    Purpose: Oxidative stress is implicated in the etiology of diabetes and its debilitating complications, such as diabetic retinopathy (DR). Various flavonoids have been reported to be useful in reducing DR progression. Myricetin derivatives (F2) isolated from leaf extract of Syzygium malaccense have the potential to serve as functional food as reported previously. The present study was performed with the aim of determining the antioxidant potential and protective effect of myricetin derivatives (F2) isolated from leaf extract of S. malaccense against glucose oxidase (GO)-induced hydrogen peroxide (H2O2) production that causes oxidative stress in ARPE-19 (RPE) cells.

    Methods: Antioxidant properties were assessed through various radical (DPPH, ABTS, and nitric oxide) scavenging assays and determination of total phenolic content and ferric reducing antioxidant power level. ARPE-19 cells were preincubated with samples before the addition of GO (to generate H2O2). Cell viability, change in intracellular reactive oxygen species (ROS), H2O2 levels in cell culture supernatant, and gene expression were assessed.

    Results: F2 showed higher antioxidant levels than the extract when assessed for radical scavenging activities and ferric reducing antioxidant power. F2 protected the ARPE-19 cells against GO-H2O2-induced oxidative stress by reducing the production of H2O2 and intracellular reactive oxygen species. This was achieved by the activation of nuclear factor erythroid 2-related factor 2 (Nrf2/NFE2L2) and superoxide dismutase (SOD2), as well as downregulation of nitric oxide producer (NOS2) at the transcriptional level.

    Conclusions: The results showed that myricetin derivatives from S. malaccense have the capacity to exert considerable exogenous antioxidant activities and stimulate endogenous antioxidant activities. Therefore, these derivatives have excellent potential to be developed as therapeutic agents for managing DR.

  17. Teh CS, Chua KH, Thong KL
    J Biomed Biotechnol, 2010;2010:817190.
    PMID: 20671932 DOI: 10.1155/2010/817190
    Molecular analysis of Malaysian Vibrio cholerae was carried out using a multiple-locus variable-number tandem repeat analysis (MLVA) assay based on 7 loci of V. cholerae. The discriminatory ability of the assay was compared with pulsed-field gel electrophoresis (PFGE) using 43 Malaysian V. cholerae isolated from various sources. In addition, the virulotypes of the strains were determined. Based on MLVA, 38 allelic profiles were obtained (F = 0.63) while PFGE generated 35 pulsotypes (F = 0.71). Simpson's index of diversity for different VNTR loci ranged from 0.59 to 0.92. The combined loci increased the discriminatory index to 0.99 which was comparable with PFGE (D = 0.99). Most of the environmental non-O1/non-O139 strains harbored rtxA, rstR, toxR, and hlyA only, and the virulotype of this serogroup was significantly different (P < .01) from clinical/environmental O1 and environmental O139 strains. In conclusion, the MLVA assay developed in this study was a useful genotyping tool with comparable discriminatory power with PFGE. In addition, the combination of the two approaches can further distinguish the strains from different sources and geographical regions of isolation.
  18. Teh CS, Chua KH, Thong KL
    Int J Med Sci, 2014;11(7):732-41.
    PMID: 24904229 DOI: 10.7150/ijms.7768
    The incidence of enteric fever caused by Salmonella enterica serovar Paratyphi A (S. Paratyphi A) is increasing in many parts of the world. Although there is no major outbreak of paratyphoid fever in recent years, S. Paratyphi A infection still remains a public health problem in many tropical countries. Therefore, surveillance studies play an important role in monitoring infections and the emergence of multidrug resistance, especially in endemic countries such as India, Nepal, Pakistan and China. In China, enteric fever was caused predominantly by S. Paratyphi A rather than by Salmonella enterica serovar Typhi (S. Typhi). Sometimes, S. Paratyphi A infection can evolve into a carrier state which increases the risk of transmission for travellers. Hence, paratyphoid fever is usually classified as a "travel-associated" disease. To date, diagnosis of paratyphoid fever based on the clinical presentation is not satisfactory as it resembles other febrile illnesses, and could not be distinguished from S. Typhi infection. With the availability of Whole Genome Sequencing technology, the genomes of S. Paratyphi A could be studied in-depth and more specific targets for detection will be revealed. Hence, detection of S. Paratyphi A with Polymerase Chain Reaction (PCR) method appears to be a more reliable approach compared to the Widal test. On the other hand, due to increasing incidence of S. Paratyphi A infections worldwide, the need to produce a paratyphoid vaccine is essential and urgent. Hence various vaccine projects that involve clinical trials have been carried out. Overall, this review provides the insights of S. Paratyphi A, including the bacteriology, epidemiology, management and antibiotic susceptibility, diagnoses and vaccine development.
  19. Puah SM, Chua KH, Tan JA
    Int J Environ Res Public Health, 2016 Feb;13(2):199.
    PMID: 26861367 DOI: 10.3390/ijerph13020199
    Staphylococcus aureus is one of the leading causes of food poisoning. Its pathogenicity results from the possession of virulence genes that produce different toxins which result in self-limiting to severe illness often requiring hospitalization. In this study of 200 sushi and sashimi samples, S. aureus contamination was confirmed in 26% of the food samples. The S. aureus isolates were further characterized for virulence genes and antibiotic susceptibility. A high incidence of virulence genes was identified in 96.2% of the isolates and 20 different virulence gene profiles were confirmed. DNA amplification showed that 30.8% (16/52) of the S. aureus carried at least one SE gene which causes staphylococcal food poisoning. The most common enterotoxin gene was seg (11.5%) and the egc cluster was detected in 5.8% of the isolates. A combination of hla and hld was the most prevalent coexistence virulence genes and accounted for 59.6% of all isolates. Antibiotic resistance studies showed tetracycline resistance to be the most common at 28.8% while multi-drug resistance was found to be low at 3.8%. In conclusion, the high rate of S. aureus in the sampled sushi and sashimi indicates the need for food safety guidelines.
  20. Nur Azlina MF, Kamisah Y, Chua KH, Qodriyah HM
    PMID: 23970937 DOI: 10.1155/2013/804796
    The present study aims to distinguish the effect of tocotrienol on an important gastric protective factor, prostaglandin E2 (PGE2), in stress-induced gastric injury. Twenty-eight Wistar rats were divided into four groups of seven rats each. Two control groups were fed commercial rat diet, and two treatment groups were fed the same diet but with additional dose of omeprazole (20 mg/kg) or tocotrienol (60 mg/kg). After 28 days, rats from one control group and both treated groups were subjected to water-immersion restraint stress for 3.5 hours once. The rats were then sacrificed, their stomach isolated and gastric juice collected, lesions examined, and gastric PGE2 content and cyclooxygenase (COX) mRNA expression were determined. Both the regimes significantly attenuated the total lesion area in the stomach compared to the control. Gastric acidity, which was increased in stress, was significantly reduced in rats supplemented with omeprazole and tocotrienol. The PGE2 content was also significantly higher in the rats given tocotrienol supplementation compared to the control followed by an increase in COX-1 mRNA expression. We conclude that tocotrienol supplementation protected rat gastric mucosa against stress-induced lesions possibly by reducing gastric acidity and preserving gastric PGE2 by increasing COX-1 mRNA.
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