Displaying publications 1 - 20 of 41 in total

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  1. Fulltext Stochasticity of bacterial attachment and its predictability by the extended derjaguin-landau-verwey-overbeek theory
    Chia TW, Nguyen VT, McMeekin T, Fegan N, Dykes GA
    Appl Environ Microbiol, 2011 Jun;77(11):3757-64.
    PMID: 21478319 DOI: 10.1128/AEM.01415-10
    Bacterial attachment onto materials has been suggested to be stochastic by some authors but nonstochastic and based on surface properties by others. We investigated this by attaching pairwise combinations of two Salmonella enterica serovar Sofia (S. Sofia) strains (with different physicochemical and attachment properties) with one strain each of S. enterica serovar Typhimurium, S. enterica serovar Infantis, or S. enterica serovar Virchow (all with similar physicochemical and attachment abilities) in ratios of 0.428, 1, and 2.333 onto glass, stainless steel, Teflon, and polysulfone. Attached bacterial cells were recovered and counted. If the ratio of attached cells of each Salmonella serovar pair recovered was the same as the initial inoculum ratio, the attachment process was deemed stochastic. Experimental outcomes from the study were compared to those predicted by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. Significant differences (P < 0.05) between the initial and the attached ratios for serovar pairs containing S. Sofia S1296a for all different ratios were apparent for all materials. For S. Sofia S1635-containing pairs, 7 out of 12 combinations of serovar pairs and materials had attachment ratios not significantly different (P > 0.05) from the initial ratio of 0.428. Five out of 12 and 10 out of 12 samples had attachment ratios not significantly different (P > 0.05) from the initial ratios of 1 and 2.333, respectively. These results demonstrate that bacterial attachment to different materials is likely to be nonstochastic only when the key physicochemical properties of the bacteria were significantly different (P < 0.05) from each other. XDLVO theory could successfully predict the attachment of some individual isolates to particular materials but could not be used to predict the likelihood of stochasticity in pairwise attachment experiments.
    Matched MeSH terms: Salmonella enterica/physiology*
  2. Antimicrobial susceptibility and occurrence of resistance genes among Salmonella enterica serovar Weltevreden from different countries
    Aarestrup FM, Lertworapreecha M, Evans MC, Bangtrakulnonth A, Chalermchaikit T, Hendriksen RS, et al.
    J Antimicrob Chemother, 2003 Oct;52(4):715-8.
    PMID: 12972453
    This study was conducted to investigate the occurrence of antimicrobial resistance among Salmonella Weltevreden isolates from different sources in South-East Asia (Indonesia, Laos, Malaysia, Taiwan, Thailand, Vietnam), Australia, Denmark, New Zealand and the USA.
    Matched MeSH terms: Salmonella enterica/drug effects*; Salmonella enterica/genetics*; Salmonella enterica/isolation & purification
  3. Fulltext Wabak demam kepialu (tifoid) di daerah Bachok, Kelantan Mac - Mei 2005
    Hamizah, M.S., Norhayati, M.N., Nor Azlina, A.R., Wan Shukri, W.S., Abdulah, H.
    Malaysian Journal of Public Health Medicine, 2005;5(2):45-49.
    MyJurnal
    Penyakit tifoid adalah penyakit berjangkit bawaan air dan makanan yang disebabkan oleh Salmonella typhii. Penyakit ini berlaku di seluruh durtia dan endemik di Kelantan. Pada April 2005, terdapat peningkatan kes tifoid yang dinotifikasi di daerah Bachok dan wabak telah diistiharkan. Pasukan siasatan telah dibentuk di mana setiap kes telahydisiasat dengan segera dan tindakan kawalan telah diambil seperti pemeriksaan dan penutupan premis makanan, kerja-kerja sanitasi dan pendidikan kesihatan. Pengesanan kes secara aktifjuga telah dilakukan. Mukim Gunong mencatatkan jumlah kes tertinggi iaitu 46.3%. Majoriti daripada kes terdiri daripadapelajar. Dua pembawa dari kalangan kontek juga turut dikesan. Lekuk epidemik menggambarkan berlakunya wabak purtca lazim. Lima daripada 1 1 1 bilangan sampel air dan dua daripada 146 bilangan sampel makanart yang diperiksa adalah positif terhadap Salmonella species tetapi tiada yang positif terhadap Salmonella typhii. Meskipun Pasar Jelawat merupakan lokasi yang disyakki sebagai punca utama jangkitan, ianya tidak dapat disahkan melalui penyiasatan dan ujan makmal.
    Matched MeSH terms: Salmonella enterica
  4. Genetic diversity of clinical and environmental strains of Salmonella enterica serotype Weltevreden isolated in Malaysia
    Thong KL, Goh YL, Radu S, Noorzaleha S, Yasin R, Koh YT, et al.
    J Clin Microbiol, 2002 Jul;40(7):2498-503.
    PMID: 12089269
    The incidence of food-borne salmonellosis due to Salmonella enterica serotype Weltevreden is reported to be on the increase in Malaysia. The pulsed-field gel electrophoresis (PFGE) subtyping method was used to assess the extent of genetic diversity and clonality of Salmonella serotype Weltevreden strains from humans and the environment. PFGE of XbaI-digested chromosomal DNA from 95 strains of Salmonella serotype Weltevreden gave 39 distinct profiles with a wide range of Dice coefficients (0.27 to 1.00), indicating that PFGE is very discriminative and that multiple clones of Salmonella serotype Weltevreden exist among clinical and environmental isolates. Strains of one dominant pulsotype (pulsotype X1/X2) appeared to be endemic in this region, as they were consistently recovered from humans with salmonellosis between 1996 and 2001 and from raw vegetables. In addition, the sharing of similar PFGE profiles among isolates from humans, vegetables, and beef provides indirect evidence of the possible transmission of salmonellosis from contaminated raw vegetables and meat to humans. Furthermore, the recurrence of PFGE profile X21 among isolates found in samples of vegetables from one wet market indicated the persistence of this clone. The environment in the wet markets may represent a major source of cross-contamination of vegetables with Salmonella serotype Weltevreden. Antibiotic sensitivity tests showed that the clinical isolates of Salmonella serotype Weltevreden remained drug sensitive but that the vegetable isolates were resistant to at least two antibiotics. To the best of our knowledge, this is the first study to compare clinical and environmental isolates of Salmonella serotype Weltevreden in Malaysia.
    Matched MeSH terms: Salmonella enterica/classification; Salmonella enterica/drug effects; Salmonella enterica/genetics*; Salmonella enterica/isolation & purification*
  5. Fulltext Salmonella meningitis in a paediatric patient caused by Salmonella enterica serotype Houtenae
    Nimir AR, Ibrahim R, Ibrahim IA
    BMJ Case Rep, 2011;2011.
    PMID: 22689601 DOI: 10.1136/bcr.04.2011.4096
    The authors report a case of a 6-week-old baby girl who was admitted to the paediatric ward due to a high fever for 2 days. The patient experienced three fits which took place while in the ward. A brain sonogram showed subdural heterogeneous collection consistent with focal empyema; however, no hydrocephalus or infarction was detected. An urgent Burr hole procedure was performed to remove the collected pus. Both blood and cerebrospinal fluid (CSF) culture grew Salmonella species which remain sensitive to some antibiotics. This strain was sent to the institute of medical research (IMR) for serotyping. The patient was treated with intravenous combination of ceftriaxone and ciprofloxacin for 3 weeks. One week later, IMR sent results that identified the strain as Salmonella enterica serotype Houtenae. Following antibiotic treatment, repeat ultrasound illustrated an improvement of the subdural empyema, and the gram stain of the CSF specimen failed to isolate bacteria.
    Matched MeSH terms: Salmonella enterica/classification*
  6. Extensively drug-resistant typhoid fever in Pakistan
    Rasheed MK, Hasan SS, Babar ZU, Ahmed SI
    Lancet Infect Dis, 2019 03;19(3):242-243.
    PMID: 30833059 DOI: 10.1016/S1473-3099(19)30051-9
    Matched MeSH terms: Salmonella enterica*
  7. Application of PCR-based serogrouping of selected Salmonella serotypes in Malaysia
    Lim BK, Thong KL
    J Infect Dev Ctries, 2009 Jul 01;3(6):420-8.
    PMID: 19762954
    BACKGROUND: Differentiation of Salmonella enterica into its serogroups is important for epidemiological study. The objective of the study was to apply a multiplex PCR targeting serogroups A, B, C1, D, E and Vi-positive strains of Salmonella enterica commonly found in Malaysia. A separate H-typing multiplex PCR which identified flagellar antigen "a", "b" or "d" was also optimized to confirm clinical serotypes, S. Paratyphi A and S. Typhi.

    METHODOLOGY: Sixty-seven laboratory Salmonella enterica strains were tested. Six sets of primers targeting defined regions of the O antigen synthesis genes (rfb gene cluster) and Vi antigen gene (viaB) were selected and combined into a multiplex PCR for O-grouping. Four primers (H-for, Ha-rev, Hb-rev and Hd-rev) were used in the second step multiplex PCR for H-typing. The optimized mPCR assays were further evaluated with 58 blind-coded Salmonella strains.

    RESULTS: The multiplex PCR results obtained showed 100% concordance to the conventionally typed serogroups. Validation with 58 blind coded Salmonella strains yield 100% accuracy and specificity.

    CONCLUSION: Based on this study, PCR serogrouping proved to be a rapid, alternative method for further differentiation of Salmonella enterica.

    Matched MeSH terms: Salmonella enterica/classification*; Salmonella enterica/genetics; Salmonella enterica/isolation & purification*
  8. Fulltext Complete Genome Sequence of Salmonella enterica subsp. enterica Serovar Typhi Isolate B/SF/13/03/195 Associated with a Typhoid Carrier in Pasir Mas, Kelantan, Malaysia
    Muhamad Harish S, Sim KS, Mohd Nor F, Mat Hussin H, Hamzah WM, Najimudin N, et al.
    Genome Announc, 2015;3(6).
    PMID: 26564035 DOI: 10.1128/genomeA.01285-15
    We report here the complete genome sequence of Salmonella enterica subsp. enterica serovar Typhi B/SF/13/03/195 obtained from a typhoid carrier, who is a food handler in Pasir Mas, Kelantan.
    Matched MeSH terms: Salmonella enterica
  9. Fulltext Characterization of multiple-antimicrobial-resistant Salmonella enterica Subsp. enterica isolated from indigenous vegetables and poultry in Malaysia
    Yoke-Kqueen C, Learn-Han L, Noorzaleha AS, Son R, Sabrina S, Jiun-Horng S, et al.
    Lett Appl Microbiol, 2008 Mar;46(3):318-24.
    PMID: 18179445 DOI: 10.1111/j.1472-765X.2007.02311.x
    The aims of this communication were to study characterization of serogroups among Salmonella isolates and the relationship of antimicrobial resistance to serogroups. Multiple antimicrobial resistance (MAR) was performed on 189 Salmonella enterica isolates associated with 38 different serovars that were recovered from poultry and four types of indigenous vegetables.
    Matched MeSH terms: Salmonella enterica/classification*; Salmonella enterica/drug effects*; Salmonella enterica/isolation & purification
  10. Fulltext Reduced fluoroquinolone susceptibility in Salmonella enterica isolates from travelers, Finland
    Lindgren MM, Kotilainen P, Huovinen P, Hurme S, Lukinmaa S, Webber MA, et al.
    Emerg Infect Dis, 2009 May;15(5):809-12.
    PMID: 19402977 DOI: 10.3201/eid1505.080849
    We tested the fluoroquinolone susceptibility of 499 Salmonella enterica isolates collected from travelers returning to Finland during 2003-2007. Among isolates from travelers to Thailand and Malaysia, reduced fluoroquinolone susceptibility decreased from 65% to 22% (p = 0.002). All isolates showing nonclassical quinolone resistance were from travelers to these 2 countries.
    Matched MeSH terms: Salmonella enterica/classification; Salmonella enterica/drug effects*; Salmonella enterica/isolation & purification
  11. Acetic acid induces pH-independent cellular energy depletion in Salmonella enterica
    Tan SM, Lee SM, Dykes GA
    Foodborne Pathog Dis, 2015 Mar;12(3):183-9.
    PMID: 25562466 DOI: 10.1089/fpd.2014.1853
    Weak organic acids are widely used as preservatives and disinfectants in the food industry. Despite their widespread use, the antimicrobial mode of action of organic acids is still not fully understood. This study investigated the effect of acetic acid on the cell membranes and cellular energy generation of four Salmonella strains. Using a nucleic acid/protein assay, it was established that acetic acid did not cause leakage of intracellular components from the strains. A scanning electron microscopy study further confirmed that membrane disruption was not the antimicrobial mode of action of acetic acid. Some elongated Salmonella cells observed in the micrographs indicated a possibility that acetic acid may inhibit DNA synthesis in the bacterial cells. Using an ATP assay, it was found that at a neutral pH, acetic acid caused cellular energy depletion with an ADP/ATP ratio in the range between 0.48 and 2.63 (p<0.05) that was apparent for the four Salmonella strains. We suggest that this effect was probably due solely to the action of undissociated acid molecules. The antimicrobial effect of acetic acid was better under acidic conditions (ADP/ATP ratio of 5.56 ± 1.27; p<0.05), where the role of both pH and undissociated acid molecules can act together. We concluded that the inhibitory effect of acetic acid is not solely attributable to acidic pH but also to undissociated acid molecules. This finding has implication for the use of acetic acid as an antimicrobial against Salmonella on food products, such as chicken meat, which can buffer its pH.
    Matched MeSH terms: Salmonella enterica/drug effects*; Salmonella enterica/ultrastructure
  12. Fulltext Overview of Molecular Typing Tools for The Characterization of Salmonella enterica in Malaysia
    Ngoi ST, Teh CS, Chai LC, Thong KL
    Biomed Environ Sci, 2015 Oct;28(10):751-64.
    PMID: 26582097 DOI: 10.3967/bes2015.105
    Matched MeSH terms: Salmonella enterica/classification; Salmonella enterica/genetics*
  13. Fulltext Mechanisms of resistance in nontyphoidal Salmonella enterica strains exhibiting a nonclassical quinolone resistance phenotype
    Gunell M, Webber MA, Kotilainen P, Lilly AJ, Caddick JM, Jalava J, et al.
    Antimicrob Agents Chemother, 2009 Sep;53(9):3832-6.
    PMID: 19596880 DOI: 10.1128/AAC.00121-09
    Nontyphoidal Salmonella enterica strains with a nonclassical quinolone resistance phenotype were isolated from patients returning from Thailand or Malaysia to Finland. A total of 10 isolates of seven serovars were studied in detail, all of which had reduced susceptibility (MIC > or = 0.125 microg/ml) to ciprofloxacin but were either susceptible or showed only low-level resistance (MIC < or = 32 microg/ml) to nalidixic acid. Phenotypic characterization included susceptibility testing by the agar dilution method and investigation of efflux activity. Genotypic characterization included the screening of mutations in the quinolone resistance-determining regions (QRDR) of gyrA, gyrB, parC, and parE by PCR and denaturing high-pressure liquid chromatography and the amplification of plasmid-mediated quinolone resistance (PMQR) genes qnrA, qnrB, qnrS, qnrD, aac(6')-Ib-cr, and qepA by PCR. PMQR was confirmed by plasmid analysis, Southern hybridization, and plasmid transfer. No mutations in the QRDRs of gyrA, gyrB, parC, or parE were detected with the exception of a Thr57-Ser substitution within ParC seen in all but the S. enterica serovar Typhimurium strains. The qnrA and qnrS genes were the only PMQR determinants detected. Plasmids carrying qnr alleles were transferable in vitro, and the resistance phenotype was reproducible in Escherichia coli DH5alpha transformants. These data demonstrate the emergence of a highly mobile qnr genotype that, in the absence of mutation within topoisomerase genes, confers the nontypical quinolone resistance phenotype in S. enterica isolates. The qnr resistance mechanism enables bacteria to survive elevated quinolone concentrations, and therefore, strains carrying qnr alleles may be able to expand during fluoroquinolone treatment. This is of concern since nonclassical quinolone resistance is plasmid mediated and therefore mobilizable.
    Matched MeSH terms: Salmonella enterica/drug effects*; Salmonella enterica/genetics*
  14. Draft genome sequence of multidrug-resistant Salmonella enterica serovar Brancaster strain PS01 isolated from chicken meat, Malaysia
    Chin PS, Yu CY, Ang GY, Yin WF, Chan KG
    J Glob Antimicrob Resist, 2017 06;9:41-42.
    PMID: 28300643 DOI: 10.1016/j.jgar.2016.12.017
    OBJECTIVES: Salmonella spp. represent one of the main diarrhoeal pathogens that are transmitted via the food supply chain. Here we report the draft genome sequence of a multidrug-resistant Salmonella enterica serovar Brancaster (PS01) that was isolated from poultry meat in Malaysia.

    METHODS: Genomic DNA was extracted from Salmonella strain PS01 and was sequenced using an Illumina HiSeq 2000 platform. The generated reads were de novo assembled using CLC Genomics Workbench. The draft genome was annotated and the presence of antimicrobial resistance genes was identified.

    RESULTS: The 5 036 442bp genome contains various antimicrobial resistance genes conferring resistance to aminoglycosides, fluoroquinolones, fosfomycin, macrolides, phenicols, sulphonamides, tetracyclines and trimethoprim. The β-lactamase gene blaTEM-176 encoding TEM-176 was also found in this strain.

    CONCLUSIONS: The genome sequence will aid in the understanding of drug resistance mechanisms in foodborne Salmonella Brancaster and highlights the need to ensure the judicious use of antibiotics in animal husbandry as well as the importance of implementing proper food handling and preparation practices.

    Matched MeSH terms: Salmonella enterica/classification; Salmonella enterica/genetics*
  15. High Phenotypic Variability among Representative Strains of Common Salmonella enterica Serovars with Possible Implications for Food Safety
    Abdullah WZW, Mackey BM, Karatzas KAG
    J Food Prot, 2018 Jan;81(1):93-104.
    PMID: 29271685 DOI: 10.4315/0362-028X.JFP-17-190
    Salmonella is an important foodborne pathogen, whose ability to resist stress and survive can vary among strains. This variability is normally not taken into account when predictions are made about survival in foods with negative consequences. Therefore, we examined the contribution of variable phenotypic properties to survival under stress in 10 Salmonella serovars. One strain (Typhimurium 10) was intentionally RpoS-negative; however, another strain (Heidelberg) showed an rpoS mutation, rendering it inactive. We assessed an array of characteristics (motility, biofilm formation, bile resistance, acid resistance, and colony morphology) that show major variability among strains associated with a 10- to 19-fold difference between the highest and the lowest strain for most characteristics. The RpoS status of isolates did not affect variability in the characteristics, with the exception of resistance to NaCl, acetic acid, lactic acid, and the combination of acetic acid and salt, where the variability between the highest and the lowest strain was reduced to 3.1-fold, 1.7-fold, 2-fold, and 1.7-fold, respectively, showing that variability was significant among RpoS-positive strains. Furthermore, we also found a good correlation between acid resistance and lysine decarboxylase activity, showing its importance for acid resistance, and demonstrated a possible role of RpoS in the lysine decarboxylase activity in Salmonella.
    Matched MeSH terms: Salmonella enterica/genetics*; Salmonella enterica/chemistry
  16. Analysis of Salmonella Agona and Salmonella Weltevreden in Malaysia by PCR fingerprinting and antibiotic resistance profiling
    Learn-Han L, Yoke-Kqueen C, Salleh NA, Sukardi S, Jiun-Horng S, Chai-Hoon K, et al.
    Antonie Van Leeuwenhoek, 2008 Oct;94(3):377-87.
    PMID: 18548329 DOI: 10.1007/s10482-008-9254-y
    Forty-eight strains of Salmonella enterica subsp. enterica serovar Agona and 33 strains of Salmonella enterica subsp. enterica serovar Weltevreden were characterized by random amplified polymorphic DNA (RAPD) fingerprinting using 3 different arbitrary primer, Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction (ERIC-PCR) and antimicrobial susceptibility testing. By using RAPD, 81 strains (44 strains of S. Agona and 33 strains of S. Weltevreden) can be clustered into 14 groups and 6 single isolates whereas ERIC-PCR produced 7 clusters and 3 single isolates. Thirteen antimicrobial agents were used and all the isolates were resistant to erythromycin and showed Multiple Antimicrobial Resistance indexes, ranging from 0.08 to 0.62. Poultry still remain as the common reservoir for multi-drug-resistant Salmonella. On the other hand, vegetables contaminated with S. Weltevreden showed a gain in antimicrobial resistance. Besides that, consistent antibiograms were observed from S. Weltevreden isolated at Kajang wet market on 2000/08/02.
    Matched MeSH terms: Salmonella enterica/classification; Salmonella enterica/drug effects; Salmonella enterica/genetics*; Salmonella enterica/pathogenicity
  17. Fulltext High resolution melting analysis for rapid mutation screening in gyrase and Topoisomerase IV genes in quinolone-resistant Salmonella enterica
    Ngoi ST, Thong KL
    Biomed Res Int, 2014;2014:718084.
    PMID: 25371903 DOI: 10.1155/2014/718084
    The increased Salmonella resistance to quinolones and fluoroquinolones is a public health concern in the Southeast Asian region. The objective of this study is to develop a high resolution melt curve (HRM) assay to rapidly screen for mutations in quinolone-resistant determining region (QRDR) of gyrase and topoisomerase IV genes. DNA sequencing was performed on 62 Salmonella strains to identify mutations in the QRDR of gyrA, gyrB, parC, and parE genes. Mutations were detected in QRDR of gyrA (n = 52; S83F, S83Y, S83I, D87G, D87Y, and D87N) and parE (n = 1; M438I). Salmonella strains with mutations within QRDR of gyrA are generally more resistant to nalidixic acid (MIC 16 > 256 μg/mL). Mutations were uncommon within the QRDR of gyrB, parC, and parE genes. In the HRM assay, mutants can be distinguished from the wild-type strains based on the transition of melt curves, which is more prominent when the profiles are displayed in difference plot. In conclusion, HRM analysis allows for rapid screening for mutations at the QRDRs of gyrase and topoisomerase IV genes in Salmonella. This assay markedly reduced the sequencing effort involved in mutational studies of quinolone-resistance genes.
    Matched MeSH terms: Salmonella enterica/enzymology; Salmonella enterica/genetics*
  18. Virulotyping of Salmonella enterica subsp. enterica isolated from indigenous vegetables and poultry meat in Malaysia using multiplex-PCR
    Khoo CH, Cheah YK, Lee LH, Sim JH, Salleh NA, Sidik SM, et al.
    Antonie Van Leeuwenhoek, 2009 Nov;96(4):441-57.
    PMID: 19565351 DOI: 10.1007/s10482-009-9358-z
    The increased occurrence of Salmonella occurrence in local indigenous vegetables and poultry meat can be a potential health hazards. This study is aimed to detect the prevalence of twenty different virulence factors among Salmonella enterica strains isolated from poultry and local indigenous vegetables in Malaysia via an optimized, rapid and specific multiplex PCR assay. The assay encompasses a total of 19 Salmonella pathogenicity islands genes and a quorum sensing gene (sdiA) in three multiplex reaction sets. A total of 114 Salmonella enterica isolates belonging to 38 different serovars were tested. Each isolate in under this study was found to possess up to 70% of the virulence genes tested and exhibited variable pathogenicity gene patterns. Reproducibility of the multiplex PCR assay was found to be 100% and the detection limit of the optimized multiplex PCR was tested with lowest detectable concentration of DNA 0.8 pg microl(-1). This study demonstrated various Salmonella pathogenicity island virulence gene patterns even within the same serovar. This sets of multiplex PCR system provide a fast and reliable typing approach based on Salmonella pathogenicity islands, thus enabling an effective monitoring of emerging pathogenic Salmonella strains as an additional tool in Salmonella surveillance studies.
    Matched MeSH terms: Salmonella enterica/classification*; Salmonella enterica/pathogenicity
  19. Fulltext Dissemination of Salmonella enterica sequence types among ASEAN economic community countries
    Patchanee P, Boonkhot P, Kittiwan N, Tadee P, Chotinun S
    Southeast Asian J. Trop. Med. Public Health, 2015 Jul;46(4):707-19.
    PMID: 26867391
    Food-borne illness caused by Salmonella enterica remains a public health problem and results in economic loss worldwide. With the up-coming establish- ment of the ASEAN Economic Community (AEC) allowing unrestricted move- ment of labor and goods, there is a higher risk of pathogen transmission among the AEC countries. This study characterized and investigated the spatial and temporal associations of S. enterica strains isolated in AEC countries during 1940- 2012 compared with those isolated in northern-Thailand during 2011-2013. Of the 173 S. enterica strains examined, 68 sequence types (STs) and 32 clonal complexes (CCs) were identified by multi loci sequence typing. Twenty-one strains belonged to four sequence types new to AEC countries, and they constituted only two CCs. A number of strains originated from various countries with multiple hosts, were highlighted. There was evidence of strains circulating in the AEC region well over a decade. Such information will be important in formulating biosecurity measures, as well as in educating regarding the risk of disease transmission in AEC.
    Matched MeSH terms: Salmonella enterica/genetics*; Salmonella enterica/isolation & purification
  20. Pathogenicity and phenotypic analysis of sopB, sopD and pipD virulence factors in Salmonella enterica serovar typhimurium and Salmonella enterica serovar Agona
    Khoo CH, Sim JH, Salleh NA, Cheah YK
    Antonie Van Leeuwenhoek, 2015 Jan;107(1):23-37.
    PMID: 25312847 DOI: 10.1007/s10482-014-0300-7
    Salmonella is an important food-borne pathogen causing disease in humans and animals worldwide. Salmonellosis may be caused by any one of over 2,500 serovars of Salmonella. Nonetheless, Salmonella enterica serovar Typhimurium and Salmonella enterica serovar Agona are the second most prevalent serovars isolated from humans and livestock products respectively. Limited knowledge is available about the virulence mechanisms responsible for diarrheal disease caused by them. To investigate the contribution of sopB, sopD and pipD as virulence factors in intracellular infections and the uniqueness of these bacteria becoming far more prevalent than other serovars, the infection model of Caenorhabditis elegans and phenotypic microarray were used to characterize their mutants. The strains containing the mutation in sopB, sopD and pipD genes were constructed by using latest site-specific group II intron mutagenesis approach to reveal the pathogenicity of the virulence factors. Overall, we observed that the mutations in sopB, sopD and pipD genes of both serovars did not exhibit significant decrease in virulence towards the nematode. This may indicate that these virulence effectors may not be universal virulence factors involved in conserved innate immunity. There are significant phenotypic differences amongst strains carrying sopB, sopD and pipD gene mutations via the analysis of biochemical profiles of the bacteria. Interestingly, mutant strains displayed different susceptibility to chemical stressors from several distinct pharmacological and structural classes when compared to its isogenic parental strains. These metabolic and chemosensitivity assays also revealed multiple roles of Salmonella virulence factors in nutrient metabolism and antibiotic resistance.
    Matched MeSH terms: Salmonella enterica/genetics; Salmonella enterica/isolation & purification; Salmonella enterica/pathogenicity*
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