Displaying publications 1 - 20 of 41 in total

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  1. 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
  2. Tunung, R., Chai, L.C., Usha, M.R., Lee, H.Y., Fatimah, A.B., Farinazleen, M.G., et al.
    MyJurnal
    Salmonella enterica is one of the major causes of bacterial foodborne infection. The aims of this study were to determine the antibiotic resistance and the genetic diversity of Salmonella enterica isolated from street foods and clinical samples and to understand the correlation between the prevalence of serovars and genotypes with their source (street food and clinical samples) and geographic origin (Negeri Sembilan, Malacca and Selangor in Peninsular Malaysia). The enterobacterial repetitive intergenic consensus (ERIC) PCR analysis distinguished the Salmonella isolates into 19 ERIC types, with one untypable isolate. Dendrograms were specifically constructed for the S. Biafra and S. Typhi isolates. Identical or very similar ERIC types among the S. Biafra isolates from street food samples indicate transmission of the S. Biafra among the street foods, as well as possible cross-contamination of the street foods. In addition, the identical or very similar ERIC types among the S. Typhi isolates from human samples examined suggest possible similarity in their source of infection. All the twenty four isolates were resistant to rifampin and none were resistant to cefuroxime. Most isolates displayed multiple resistances. Dendrogram of antibiotic resistances produced six clusters, with similarity levels between 18.8% and 100%. Generally, street food and clinical isolates tend to cluster apart. Dendrogram to cluster the antibiotic groups showed that they could be grouped according to classes based on mode of inhibition. The findings suggest that street food contaminated with drug-resistant Salmonella enterica can be an important factor in the continuous emergence of antibiotic resistant Salmonella enterica.
    Matched MeSH terms: Salmonella enterica
  3. Thong KL, Ngoi ST, Chai LC, Teh CS
    Microb Drug Resist, 2016 Jun;22(4):259-72.
    PMID: 26683630 DOI: 10.1089/mdr.2015.0158
    The prevalence of quinolone-resistant Salmonella enterica is on the rise worldwide. Salmonella enterica is one of the major foodborne pathogens in Malaysia. Therefore, we aim to investigate the occurrence and mechanisms of quinolone resistance among Salmonella strains isolated in Malaysia. A total of 283 Salmonella strains isolated from food, humans, and animals were studied. The disk diffusion method was used to examine the quinolone susceptibility of the strains, and the minimum inhibitory concentration (MIC) values of nalidixic acid and ciprofloxacin were also determined. DNA sequencing of the quinolone resistance-determining regions (QRDRs) of gyrase and topoisomerase IV genes and the plasmid-borne qnr genes was performed. The transfer of the qnr gene was examined through transconjugation experiment. A total of 101 nalidixic acid-resistant Salmonella strains were identified. In general, all strains were highly resistant to nalidixic acid (average MICNAL, 170 μg/ml). Resistance to ciprofloxacin was observed in 30.7% of the strains (1 ≤ MICCIP ≤ 2 μg/ml). Majority of the strains contained missense mutations in the QRDR of gyrA (69.3%). Silent mutations were frequently detected in gyrB (75.2%), parC (27.7%), and parE (51.5%) within and beyond the QRDRs. Novel mutations were detected in parC and parE. The plasmid-borne qnrS1 variant was found in 36.6% of the strains, and two strains were found to be able to transfer the qnrS1 gene. Overall, mutations in gyrA and the presence of qnrS1 genes might have contributed to the high level of quinolone resistance among the strains. Our study provided a better understanding on the status of quinolone resistance among Salmonella strains circulating in Malaysia.
    Matched MeSH terms: Salmonella enterica/drug effects*; Salmonella enterica/genetics; Salmonella enterica/isolation & purification; Salmonella enterica/metabolism
  4. Thong KL, Bakeri SA, Lai KS, Koh YT, Taib MZ, Lim VK, et al.
    PMID: 15272750
    Pulsed field gel electrophoresis (PFGE) and antimicrobial susceptibility analysis were undertaken on twenty-three strains of Salmonella enterica serovar Tshiongwe, an unusual serovar, which recently emerged in Malaysia. Antimicrobial susceptibility analysis showed that all the strains were sensitive to ampicilin, chloramphenicol, cotrimoxazole, and kanamycin. Twenty (87%) and 8 (3.5%) strains had resistance to tetracycline and streptomycin respectively. PFGE analysis subtyped 23 strains into 10 profiles (Dice coefficient of similarity, F = 0.7-1.0). The predominant profile, X1 was found in both clinical and environmental isolates and was widely distributed in different parts of Malaysia during the study period. In addition, isolates recovered from food, a hand-towel, apron and the surface of a table-top in one particular location had unique, indistinguishable profiles (X4/4a) and identical antibiograms. Similarly, isolates from cooked meat and a chopping board had PFGE profiles similar to some human isolates. These probably indicated cross-contamination and poor hygiene in food practices, hence contributing to Salmonellosis. Factors causing the emergence of this rare Salmonella serovar being responsible for food poisoning episodes during the study period remained unclear. The study reiterated the usefulness and versatility of PFGE in the molecular subtyping of this rare Salmonella serovar in Malaysia.
    Matched MeSH terms: Salmonella enterica/classification*
  5. 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*
  6. 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
  7. Tan MS, Moore SC, Tabor RF, Fegan N, Rahman S, Dykes GA
    BMC Microbiol, 2016 09 15;16:212.
    PMID: 27629769 DOI: 10.1186/s12866-016-0832-2
    BACKGROUND: Processing of fresh produce exposes cut surfaces of plant cell walls that then become vulnerable to human foodborne pathogen attachment and contamination, particularly by Salmonella enterica. Plant cell walls are mainly composed of the polysaccharides cellulose, pectin and hemicelluloses (predominantly xyloglucan). Our previous work used bacterial cellulose-based plant cell wall models to study the interaction between Salmonella and the various plant cell wall components. We demonstrated that Salmonella attachment was favoured in the presence of pectin while xyloglucan had no effect on its attachment. Xyloglucan significantly increased the attachment of Salmonella cells to the plant cell wall model only when it was in association with pectin. In this study, we investigate whether the plant cell wall polysaccharides mediate Salmonella attachment to the bacterial cellulose-based plant cell wall models through specific carbohydrate interactions or through the effects of carbohydrates on the physical characteristics of the attachment surface.

    RESULTS: We found that none of the monosaccharides that make up the plant cell wall polysaccharides specifically inhibit Salmonella attachment to the bacterial cellulose-based plant cell wall models. Confocal laser scanning microscopy showed that Salmonella cells can penetrate and attach within the tightly arranged bacterial cellulose network. Analysis of images obtained from atomic force microscopy revealed that the bacterial cellulose-pectin-xyloglucan composite with 0.3 % (w/v) xyloglucan, previously shown to have the highest number of Salmonella cells attached to it, had significantly thicker cellulose fibrils compared to other composites. Scanning electron microscopy images also showed that the bacterial cellulose and bacterial cellulose-xyloglucan composites were more porous when compared to the other composites containing pectin.

    CONCLUSIONS: Our study found that the attachment of Salmonella cells to cut plant cell walls was not mediated by specific carbohydrate interactions. This suggests that the attachment of Salmonella strains to the plant cell wall models were more dependent on the structural characteristics of the attachment surface. Pectin reduces the porosity and space between cellulose fibrils, which then forms a matrix that is able to retain Salmonella cells within the bacterial cellulose network. When present with pectin, xyloglucan provides a greater surface for Salmonella cells to attach through the thickening of cellulose fibrils.

    Matched MeSH terms: Salmonella enterica/physiology
  8. Tan MS, Rahman S, Dykes GA
    Appl Environ Microbiol, 2016 01 15;82(2):680-8.
    PMID: 26567310 DOI: 10.1128/AEM.02609-15
    Minimally processed fresh produce has been implicated as a major source of foodborne microbial pathogens globally. These pathogens must attach to the produce in order to be transmitted. Cut surfaces of produce that expose cell walls are particularly vulnerable. Little is known about the roles that different structural components (cellulose, pectin, and xyloglucan) of plant cell walls play in the attachment of foodborne bacterial pathogens. Using bacterial cellulose-derived plant cell wall models, we showed that the presence of pectin alone or xyloglucan alone affected the attachment of three Salmonella enterica strains (Salmonella enterica subsp. enterica serovar Enteritidis ATCC 13076, Salmonella enterica subsp. enterica serovar Typhimurium ATCC 14028, and Salmonella enterica subsp. indica M4) and Listeria monocytogenes ATCC 7644. In addition, we showed that this effect was modulated in the presence of both polysaccharides. Assays using pairwise combinations of S. Typhimurium ATCC 14028 and L. monocytogenes ATCC 7644 showed that bacterial attachment to all plant cell wall models was dependent on the characteristics of the individual bacterial strains and was not directly proportional to the initial concentration of the bacterial inoculum. This work showed that bacterial attachment was not determined directly by the plant cell wall model or bacterial physicochemical properties. We suggest that attachment of the Salmonella strains may be influenced by the effects of these polysaccharides on physical and structural properties of the plant cell wall model. Our findings improve the understanding of how Salmonella enterica and Listeria monocytogenes attach to plant cell walls, which may facilitate the development of better ways to prevent the attachment of these pathogens to such surfaces.
    Matched MeSH terms: Salmonella enterica/physiology*
  9. Sulaiman W
    Malays J Med Sci, 2006 Jul;13(2):64-5.
    PMID: 22589607 MyJurnal
    Malaysia is endemic for both these diseases and one should not be too surprised when faced with a diagnosis of co-infection of typhoid and malaria, as have been described in India and Canada. Here we describe one such case of Salmonella typhi and Plasmodium vivax infection.
    Matched MeSH terms: Salmonella enterica
  10. Sulaiman H, Ponnampalavanar S, Mun KS, Italiano CM
    BMC Infect Dis, 2013 Nov 09;13:527.
    PMID: 24209898 DOI: 10.1186/1471-2334-13-527
    BACKGROUND: Infections due to Mycobacterium tuberculosis, Burkholderia pseudomallei and non-typhoidal Salmonella cause significant morbidity and mortality throughout the world. These intracellular pathogens share some common predisposing factors and clinical features. Co-infection with two of these organisms has been reported previously but, to our knowledge, this is the first time that infection with all three has been reported in one person.

    CASE PRESENTATION: In September 2010, a 58-year-old diabetic Malaysian male presented with fever and a fluctuant mass on the right side of his neck. B. pseudomallei was isolated from an aspirate of this lesion and there was radiological evidence of disseminated infection in the liver and spleen. The recurrence of clinical symptoms over ensuing months prompted further aspiration and biopsy of a cervical abscess and underlying lymph nodes. Salmonella enterica serovar Stanley and then M. tuberculosis were identified from these specimens by culture and molecular methods. The patient responded to targeted medical management of each of these infections.

    CONCLUSION: In endemic settings, a high index of suspicion and adequate tissue sampling are imperative in identifying these pathogenic organisms. Diabetes was identified as a predisposing factor in this case while our understanding of other potential risk factors is evolving.

    Matched MeSH terms: Salmonella enterica/isolation & purification
  11. 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*
  12. Patchanee P, Boonkhot P, Kittiwan N, Tadee P, Chotinun S
    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
  13. Nuramira Azizan, Nihayah Mohamad, Ahmad Zorin Sahalan
    MyJurnal
    Bunga rafflesia cantleyi Solms-Laubach merupakan salah satu jenis tumbuhan liar boleh ditemui di hutan tanah rendah di Semenanjung Malaysia dan digunakan secara meluas dalam ubatan tradisional. Objektif utama dalam kajian ini adalah untuk menguji keberkesanan ekstrak tumbuhan ini sebagai agen aktiviti antibakteria. rafflesia cantleyi Solms-Laubach diesktrak dengan menggunakan tiga kaedah pengekstrakkan berperingkat iaitu petroleum eter (PE) diikuti dengan etil asetat (EA) dan berakhir dengan etanol. Kesemua ekstrak ini kemudiannya diuji terhadap beberapa bakteria ujian iaitu Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis, Escherichia coli ATCC 25922 dan Salmonella typhimurium dengan menggunakan kaedah resapan telaga. Hasil keputusan menunjukkan ekstrak etil asetat dan etanol mempunyai kesan perencatan bakteria yang baik, manakala ekstrak petroleum eter langsung tidak menunjukkan sebarang aktiviti antibakteria. Hasil kajian juga mendapati bahawa ekstrak etil asetat lebih ketara merencat kesemua bakteria yang diuji berbanding dengan ekstrak ethanol. Dua ujian lain yang dijalankan iaitu ujian penentuan nilai kepekatan perencatan minimum (MIC) dan nilai kepekatan minimum bakterisidal (MBC) didapati menyokong keputusan ujian kaedah resapan telaga di mana nilai MIC yang diperoleh bagi ekstrak etil asetat adalah lebih rendah iaitu dalam julat 6.25 hingga 12.5 mg/ml dan nilai MBC pula dalam julat 25.0 hingga 50.0 mg/ml berbanding ekstrak etanol dengan nilai MIC yang lebih besar iaitu dalam julat 25.0 hingga 50.0 mg/ml dan nilai MBCnya adalah 100.0 mg/ml.
    Matched MeSH terms: Salmonella enterica
  14. 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*
  15. 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*
  16. 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*
  17. Muniandy S, Teh SJ, Appaturi JN, Thong KL, Lai CW, Ibrahim F, et al.
    Bioelectrochemistry, 2019 Jun;127:136-144.
    PMID: 30825657 DOI: 10.1016/j.bioelechem.2019.02.005
    Recent foodborne outbreaks in multiple locations necessitate the continuous development of highly sensitive and specific biosensors that offer rapid detection of foodborne biological hazards. This work focuses on the development of a reduced graphene oxide‑titanium dioxide (rGO-TiO2) nanocomposite based aptasensor to detect Salmonella enterica serovar Typhimurium. A label-free aptamer was immobilized on a rGO-TiO2 nanocomposite matrix through electrostatic interactions. The changes in electrical conductivity on the electrode surface were evaluated using electroanalytical methods. DNA aptamer adsorbed on the rGO-TiO2 surface bound to the bacterial cells at the electrode interface causing a physical barrier inhibiting the electron transfer. This interaction decreased the DPV signal of the electrode proportional to decreasing concentrations of the bacterial cells. The optimized aptasensor exhibited high sensitivity with a wide detection range (108 to 101 cfu mL-1), a low detection limit of 101 cfu mL-1 and good selectivity for Salmonella bacteria. This rGO-TiO2 aptasensor is an excellent biosensing platform that offers a reliable, rapid and sensitive alternative for foodborne pathogen detection.
    Matched MeSH terms: Salmonella enterica/isolation & purification*
  18. Muhamad Harish S, Sim KS, Najimudin N, Aziah I
    Genome Announc, 2015;3(6).
    PMID: 26564032 DOI: 10.1128/genomeA.01261-15
    Salmonella enterica subsp. enterica serovar Typhi is a human-restricted pathogen that causes typhoid fever. Even though it is a human-restricted pathogen, the bacterium is also isolated from environments such as groundwater and pond water. Here, we describe the genome sequence of the Salmonella enterica subsp. enterica serovar Typhi PM016/13 which was isolated from well water during a typhoid outbreak in Kelantan, Malaysia, in 2013.
    Matched MeSH terms: Salmonella enterica
  19. 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
  20. 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
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