Displaying publications 1 - 20 of 131 in total

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  1. Fletcher W
    Matched MeSH terms: Salmonella typhi
  2. Pang T, Calva E, Punjabi N, Rowley D
    Asian Pac J Allergy Immunol, 1992 Jun;10(1):73-7.
    PMID: 1358084
    Matched MeSH terms: Salmonella typhi/genetics; Salmonella typhi/immunology; Salmonella typhi/pathogenicity
  3. Pang T
    Trends Microbiol., 1998 Sep;6(9):339-42.
    PMID: 9778724
    Matched MeSH terms: Salmonella typhi/genetics*; Salmonella typhi/pathogenicity
  4. Jegathesan M
    J Hyg (Lond), 1983 Feb;90(1):91-7.
    PMID: 6822730
    The pattern of phage types of 2553 strains of Salmonella typhi isolated over the 10-year period 1970-9 was studied. During the period 29 different phage types were encountered, not including the categories of 'untypable strains', 'degraded Vi-strains' and Vi negative strains. For the period as a whole, the commonest phage types encountered were A (20.9%), E1 (14.8%), D1 (10.3%), degraded Vi positive strains (10.3%), untypable Vi strains (7.3%), C4 (7.1%), D2 (4.4%), E2 (3.9%) and type 25 (2.6%). There were phage types which appeared in the early years of the period and then disappeared (types B2, D9 and D1-N). Others only made their appearance in recent years (K1 and 53). Notable differences were also seen in the predilection of some phage types for certain geographical areas.
    Matched MeSH terms: Salmonella typhi/classification*; Salmonella typhi/isolation & purification
  5. Ong SY, Pratap CB, Wan X, Hou S, Abdul Rahman AY, Saito JA, et al.
    J Bacteriol, 2012 Apr;194(8):2115-6.
    PMID: 22461552 DOI: 10.1128/JB.00121-12
    We report here the complete genome sequence of Salmonella enterica subsp. enterica serovar Typhi P-stx-12, a clinical isolate obtained from a typhoid carrier in India.
    Matched MeSH terms: Salmonella typhi/classification*; Salmonella typhi/genetics*
  6. Pang T, Puthucheary SD
    J Clin Pathol, 1983 Apr;36(4):471-5.
    PMID: 6833514
    The diagnostic value of the Widal test was assessed in an endemic area. The test was done on 300 normal individuals, 297 non-typhoidal fevers and 275 bacteriologically proven cases of typhoid. Of 300 normal individuals, 2% had an H agglutinin titre of 1/160 and 5% had an O agglutinin titre of 1/160. On the basis of these criteria a significant H and/or O agglutinin titre of 1/320 or more was observed in 93-97% of typhoid cases and in only 3% of patients with non-typhoidal fever. Of the sera from typhoid cases which gave a significant Widal reaction, the majority (79.9%) showed increases in both H and O agglutinins and 51 of 234 (21.8%) of these sera were collected in the first week of illness. The significance and implications of these findings are discussed.
    Matched MeSH terms: Salmonella typhi/immunology; Salmonella typhi/isolation & purification
  7. Chin KCJ, Taylor TD, Hebrard M, Anbalagan K, Dashti MG, Phua KK
    BMC Genomics, 2017 Oct 31;18(1):836.
    PMID: 29089020 DOI: 10.1186/s12864-017-4212-6
    BACKGROUND: Typhoid fever is an acute systemic infection of humans caused by Salmonella enterica subspecies enterica serovar Typhi (S. Typhi). In chronic carriers, the bacteria survive the harsh environment of the gallbladder by producing biofilm. The phenotype of S. Typhi biofilm cells is significantly different from the free-swimming planktonic cells, and studies have shown that they are associated with antibiotic resistance, immune system evasion, and bacterial persistence. However, the mechanism of this transition and the events leading to biofilm formation are unknown. High throughput sequencing was performed to identify the genes involved in biofilm formation and to postulate the mechanism of action.

    RESULTS: Planktonic S. Typhi cells were cultured using standard nutrient broth whereas biofilm cells were cultured in a stressful environment using high shearing-force and bile to mimic the gallbladder. Sequencing libraries were prepared from S. Typhi planktonic cells and mature biofilm cells using the Illumina HiSeq 2500 platform, and the transcriptome data obtained were processed using Cufflinks bioinformatics suite of programs to investigate differential gene expression between the two phenotypes. A total of 35 up-regulated and 29 down-regulated genes were identified. The identities of the differentially expressed genes were confirmed using NCBI BLAST and their functions were analyzed. The results showed that the genes associated with metabolic processes and biofilm regulations were down-regulated while those associated with the membrane matrix and antibiotic resistance were highly up-regulated.

    CONCLUSIONS: It is proposed that the biofilm phenotype of S. Typhi allows the bacteria to increase production of the membrane matrix in order to serve as a physical shield and to adhere to surfaces, and enter an energy conservation state in response to the stressful environment. Conversely, the planktonic phenotype allows the bacteria to produce flagella and increase metabolic activity to enable the bacteria to migrate and form new colonies of infection. This data provide a basis for further studies to uncover the mechanism of biofilm formation in S. Typhi and to discover novel genes or pathways associated with the development of the typhoid carrier state.

    Matched MeSH terms: Salmonella typhi/genetics*; Salmonella typhi/growth & development*
  8. Kalai Chelvam K, Yap KP, Chai LC, Thong KL
    PLoS One, 2015;10(5):e0126207.
    PMID: 25946205 DOI: 10.1371/journal.pone.0126207
    Salmonella enterica serovar Typhi (S. Typhi) is a foodborne pathogen that causes typhoid fever and infects only humans. The ability of S. Typhi to survive outside the human host remains unclear, particularly in human carrier strains. In this study, we have investigated the catabolic activity of a human carrier S. Typhi strain in both planktonic and biofilm cells using the high-throughput Biolog Phenotype MicroArray, Minimum Biofilm Eradication Concentration (MBEC) biofilm inoculator (96-well peg lid) and whole genome sequence data. Additional strains of S. Typhi were tested to further validate the variation of catabolism in selected carbon substrates in the different bacterial growth phases. The analyzes of the carbon utilization data indicated that planktonic cells of the carrier strain, S. Typhi CR0044 could utilize a broader range of carbon substrates compared to biofilm cells. Pyruvic acid and succinic acid which are related to energy metabolism were actively catabolised in the planktonic stage compared to biofilm stage. On the other hand, glycerol, L-fucose, L-rhamnose (carbohydrates) and D-threonine (amino acid) were more actively catabolised by biofilm cells compared to planktonic cells. Notably, dextrin and pectin could induce strong biofilm formation in the human carrier strain of S. Typhi. However, pectin could not induce formation of biofilm in the other S. Typhi strains. Phenome data showed the utilization of certain carbon substrates which was supported by the presence of the catabolism-associated genes in S. Typhi CR0044. In conclusion, the findings showed the differential carbon utilization between planktonic and biofilm cells of a S. Typhi human carrier strain. The differences found in the carbon utilization profiles suggested that S. Typhi uses substrates mainly found in the human biliary mucus glycoprotein, gallbladder, liver and cortex of the kidney of the human host. The observed diversity in the carbon catabolism profiles among different S. Typhi strains has suggested the possible involvement of various metabolic pathways that might be related to the virulence and pathogenesis of this host-restricted human pathogen. The data serve as a caveat for future in-vivo studies to investigate the carbon metabolic activity to the pathogenesis of S. Typhi.
    Matched MeSH terms: Salmonella typhi/genetics; Salmonella typhi/pathogenicity*; Salmonella typhi/physiology*
  9. Ismail A, Hai OK, Kader ZA
    Biochem Biophys Res Commun, 1991 Nov 27;181(1):301-5.
    PMID: 1958200
    Current studies were undertaken to determine the presence of a specific antigenic protein on the outer membrane of Salmonella typhi. Immunoblot analysis using sera from patients with fevers revealed that the 50 kD band was specifically recognized only by typhoid sera. The 50 kD band located on the outer membrane is protein by nature and is not a Vi (capsular), dH (flagellar), or O9 (somatic) antigen of S. typhi. These results indicate the usefulness of the specific antigen in the development of a serodiagnostic test for typhoid fever since antibodies of both the IgM and IgG class responses were obtained.
    Matched MeSH terms: Salmonella typhi/immunology*; Salmonella typhi/isolation & purification; Salmonella typhi/pathogenicity
  10. Koh CL, Lim ME, Wong YH
    Med J Malaysia, 1983 Dec;38(4):320-4.
    PMID: 6599991
    A clinical isolate of Salmonella typhi (Vi phage type 25), resistant to chloramphenicol, streptomycin and tetracycline, was examined for the presence of R plasmids. Results from conjugation, agarose gel electrophoresis and transformation experiments indicated that it harboured a single large self-transmissible R plasmid which coded for both the chloramphenicol and tetracycline resistance traits.
    Matched MeSH terms: Salmonella typhi/drug effects; Salmonella typhi/genetics*; Salmonella typhi/isolation & purification
  11. Kalai Chelvam K, Chai LC, Thong KL
    Gut Pathog, 2014;6(1):2.
    PMID: 24499680 DOI: 10.1186/1757-4749-6-2
    Salmonella enterica serovar Typhi (S. Typhi) exhibits unique characteristics as an intracellular human pathogen. It causes both acute and chronic infection with various disease manifestations in the human host only. The principal factors underlying the unique lifestyle of motility and biofilm forming ability of S. Typhi remain largely unknown. The main objective of this study was to explore and investigate the motility and biofilm forming behaviour among S. Typhi strains of diverse background.
    Matched MeSH terms: Salmonella typhi
  12. Ismail A
    Malays J Med Sci, 2000 Jul;7(2):3-8.
    PMID: 22977383 MyJurnal
    For effective management of typhoid, diagnosis of the disease must be done with speed and accuracy. Development of such a test would require antigens that are specific for typhoid diagnosis. Attempts at finding the specific antigen have been carried out throughout the years. The finding of such an antigen can lead to carrier detection as well. Candidate antigens have been used in the development of antigen or antibody detection tests with variation in sensitivity and specificity. Further characterization and understanding of the candidate antigens combined with use of innovative technologies will allow for the ideal test for typhoid and typhoid carriers to be within reach.
    Matched MeSH terms: Salmonella typhi
  13. Lau KL, Ong EB, Zainudin ZF, Samian MR, Ismail A, Najimudin N
    J Gen Appl Microbiol, 2013;59(3):239-44.
    PMID: 23863294
    Matched MeSH terms: Salmonella typhi/genetics; Salmonella typhi/growth & development; Salmonella typhi/metabolism; Salmonella typhi/physiology*
  14. Yuen HL, Shamala D, Thong KL
    J Infect Dev Ctries, 2008 Aug 30;2(4):313-23.
    PMID: 19741295
    BACKGROUND: Heat shock proteins (HSPs) are known to be involved in the pathogenesis of Salmonella enterica serovar Typhi (S. Typhi), the causative agent of typhoid fever. The objective of this study was to apply a phage display library to identify mimotopes of two HSPs, HSP90 and DnaK in S. Typhi.

    METHODOLOGY: A 12-mer random peptide library expressed on the surface of the filamentous phage, M13, was used to select the mimotopes of two S. Typhi heat shock proteins by biopanning with monoclonal antibodies (mAbs), DnaK and HSP90. The immunogenicity of the selected peptides was determined through binding affinity with polyclonal antibodies from pooled typhoid-confirmed patients' sera and purified HSPs mAb using Western blotting and ELISA.

    RESULTS: Five rounds of biopanning resulted in enrichment of phage clones expressing the binding motifs TDxSTRP and FPSHYWLYPPPT, respectively. The selected peptides showed strong immunoreactivity with patients' sera. Thus, monoclonal antibodies against HSP and patient sera can select common mimotopes from the random peptide library.

    CONCLUSION: These findings may provide fundamental information for further studies on diagnostic application or vaccine design against this aetiologic agent of typhoid fever.

    Matched MeSH terms: Salmonella typhi/immunology*
  15. Yusof WN, Nagaratnam M, Koh CL, Puthucheary S, Pang T
    Microbiol. Immunol., 1993;37(8):667-70.
    PMID: 8246829
    Human mononuclear cells pre-labeled with [3H]arachidonic acid were shown to release metabolites following in vitro addition of heat-killed Salmonella typhi (HKST). The amount of label released was significantly higher than that seen with live S. typhi (LST). Addition of increasing amounts of HKST resulted in an increased release of metabolites. Enzyme immunoassay of the culture supernatants revealed that the bulk of the metabolite released was prostaglandin E2 (PGE2). Leukotriene B4 (LTB4) and leukotriene C4 (LTC4) were not detectable in the culture supernatants. The significance and implications of these results are discussed.
    Matched MeSH terms: Salmonella typhi*
  16. Cheong YM, Jegathesan M
    Med J Malaysia, 1992 Dec;47(4):331.
    PMID: 1303490
    Matched MeSH terms: Salmonella typhi/drug effects*
  17. Phipps M, Pang T, Koh CL, Puthucheary S
    Microbiol. Immunol., 1991;35(2):157-61.
    PMID: 1886492
    Seven (6.1%) of 115 strains of Salmonella typhi isolated from Malaysian patients harbored a single large plasmid of 71 to 166 mD. Two of the seven plasmid-bearing strains were resistant to chloramphenicol (Cm) and tetracycline (Tc) and they transferred Cm and Tc resistance traits to Escherichia coli K12 at frequencies from 1.6 x 10(-7) to 1.9 x 10(-6). Agarose gel electrophoresis provided evidence that the resistance traits were cotransferred on a conjugative plasmid. The significance and importance of these results are discussed.
    Matched MeSH terms: Salmonella typhi/genetics*
  18. Cheong YM, Jegathesan M
    Med J Malaysia, 1989 Sep;44(3):267.
    PMID: 2483249
    Matched MeSH terms: Salmonella typhi/immunology
  19. Pang T, Pothocheary SD
    PMID: 2672364
    Matched MeSH terms: Salmonella typhi/isolation & purification; Salmonella typhimurium/isolation & purification
  20. Singh RB
    Med J Malaya, 1966 Mar;20(3):215-20.
    PMID: 4223129
    Matched MeSH terms: Salmonella typhi/isolation & purification*
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