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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
Antibiotic susceptibility and molecular characterization of Salmonella enterica serovar Paratyphi B isolated from vegetables and processing environment in Malaysia

Abatcha MG, Effarizah ME, Rusul G

Int J Food Microbiol, 2019 Feb 02;290:180-183.
PMID: 30342248 DOI: 10.1016/j.ijfoodmicro.2018.09.021

Salmonella enterica serovar Paratyphi B (S. Paratyphi B) is a major foodborne pathogen distributed all over the world. However, little is known about the antibiotic resistance, genetic relatedness and virulence profile of S. Paratyphi B isolated from leafy vegetables and the processing environment in Malaysia. In this study, 6 S. Paratyphi B isolates were recovered from different vegetables and drain water of processing areas obtained from fresh food markets in Malaysia. The isolates were characterized by antibiogram, Pulsed-field gel electrophoresis (PFGE) and virulence genes. Antibiotic susceptibility test showed that 3 of the isolates were resistant to the antibiotics. These include S. Paratyphi B SP251 isolate, which was resistant to chloramphenicol, ampicillin, sulfonamides and streptomycin; Isolate SP246 which was resistant to chloramphenicol, sulfonamides and streptomycin and Isolate SP235 showing resistance to nalidixic acid only. PFGE subtyped the 6 S. Paratyphi B isolates into 6 distinct XbaI-pulsotypes, with a wide range of genetic similarity (0.55 to 0.9). The isolates from different sources and fresh food markets location were genetically diverse. Thirteen (tolC, orgA, spaN, prgH, sipB, invA, pefA, sofB, msgA, cdtB, pagC, spiA and spvB) out of the 17 virulence genes tested were found in all of the S. Paratyphi B isolates. Another gene (lpfC), was found only in one isolate (SP051). None of the isolates possessed sifA, sitC and ironN genes. In summary, this study provides unique information on antibiotic resistance, genetic relatedness, and virulotyping of S. Paratyphi B isolated from leafy vegetables and processing environment.

Matched MeSH terms: Salmonella enterica/isolation & purification
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
Fulltext Gut bacteria of Cuora amboinensis (turtle) produce broad-spectrum antibacterial molecules

Akbar N, Khan NA, Sagathevan K, Iqbal M, Tawab A, Siddiqui R

Sci Rep, 2019 11 18;9(1):17012.
PMID: 31740685 DOI: 10.1038/s41598-019-52738-w

Antimicrobial resistance is a major threat to human health, hence there is an urgent need to discover antibacterial molecule(s). Previously, we hypothesized that microbial gut flora of animals are a potential source of antibacterial molecules. Among various animals, Cuora amboinensis (turtle) represents an important reptile species living in diverse ecological environments and feed on organic waste and terrestrial organisms and have been used in folk medicine. The purpose of this study was to mine turtle's gut bacteria for potential antibacterial molecule(s). Several bacteria were isolated from the turtle gut and their conditioned media were prepared. Conditioned media showed potent antibacterial activity against several Gram-positive (Bacillus cereus, Streptococcus pyogenes and methicillin-resistant Staphylococcus aureus) and Gram-negative (neuropathogenic Escherichia coli K1, Serratia marcescens, Pseudomonas aeruginosa, Salmonella enterica and Klebsiella pneumoniae) pathogenic bacteria. Conditioned media-mediated bactericidal activity was heat-resistant when treated at 95°C for 10 min. By measuring Lactate dehydrogenase release, the results showed that conditioned media had no effect on human cell viability. Tandem Mass Spectrometric analysis revealed the presence of various secondary metabolites, i.e., a series of known as well as novel N-acyl-homoserine lactones, several homologues of 4-hydroxy-2-alkylquinolines, and rhamnolipids, which are the signature metabolites of Pseudomonas species. These findings are significant and provide the basis for rational development of therapeutic interventions against bacterial infections.

Matched MeSH terms: Salmonella enterica/drug effects; Salmonella enterica/physiology
Fulltext Gut Bacteria of Water Monitor Lizard (Varanus salvator) Are a Potential Source of Antibacterial Compound(s)

Akbar N, Siddiqui R, Sagathevan K, Iqbal M, Khan NA

Antibiotics (Basel), 2019 Sep 24;8(4).
PMID: 31554316 DOI: 10.3390/antibiotics8040164

For the past few decades, there has been limited progress in the development of novel antibacterials. Previously, we postulated that the gut microbiota of animals residing in polluted environments are a forthcoming supply of antibacterials. Among various species, the water monitor lizard is an interesting species that feeds on organic waste and the carcass of wild animals. Gut microbiota of the water monitor lizard were sequestered, identified and cultivated in RPMI-1640 to produce conditioned medium (CM). Next, the antimicrobial properties of CM were evaluated versus a selection of Gram-negative (Escherichia coli K1, Serratia marcescens,Pseudomonas aeruginosa, Salmonella enterica and Klebsiella pneumoniae) and Gram-positive bacteria (Streptococcus pyogenes, methicillin-resistant Staphylococcus aureus, and Bacillus cereus). CM were partially characterized by heat inactivation at 95°C for 10 min and tested against P. aeruginosa and S. pyogenes. CM were also tested against immortalized human keratinocytes (HaCaT) cells lines. The results demonstrated that gut microbiota isolated from water monitor lizard produced molecules with remarkable bactericidal activities. To determine the identity of the active molecules, CM were subjected to Liquid Chromatography-Mass Spectrometry. Several molecules were identified belonging to the classes of flavonoids, terpenoids, alkaloids, polyhydroxy alkaloids, polyacetylenes, bisphenols, amides, oxylipin and pyrazine derivatives with known broad-spectrum antimicrobial, anti-tumour, anti-oxidant, anti-inflammatory, and analgesic attributes. Furthermore, the detailed analysis of these molecules could lead us to develop effective therapeutic antibacterials.

Matched MeSH terms: Salmonella enterica
Fulltext Gut Bacteria of Rattus rattus (Rat) Produce Broad-Spectrum Antibacterial Lipopeptides

Akbar N, Siddiqui R, Iqbal M, Sagathevan K, Kim KS, Habib F, et al.

ACS Omega, 2021 May 11;6(18):12261-12273.
PMID: 34056379 DOI: 10.1021/acsomega.1c01137

Among several animals, Rattus rattus (rat) lives in polluted environments and feeds on organic waste/small invertebrates, suggesting the presence of inherent mechanisms to thwart infections. In this study, we isolated gut bacteria of rats for their antibacterial activities. Using antibacterial assays, the findings showed that the conditioned media from selected bacteria exhibited bactericidal activities against Gram-negative (Escherichia coli K1, Klebsiella pneumoniae, Pseudomonas aeruginosa, Serratia marcescens, and Salmonella enterica) and Gram-positive (Bacillus cereus, methicillin-resistant Staphylococcus aureus, and Streptococcus pyogenes) pathogenic bacteria. The conditioned media retained their antibacterial properties upon heat treatment at boiling temperature for 10 min. Using MTT assays, the conditioned media showed minimal cytotoxic effects against human keratinocyte cells. Active conditioned media were subjected to tandem mass spectrometry, and the results showed that conditioned media from Bacillus subtilis produced a large repertoire of surfactin and iturin A (lipopeptides) molecules. To our knowledge, this is the first report of isolation of lipopeptides from bacteria isolated from the rat gut. In short, these findings are important and provide a platform to develop effective antibacterial drugs.

Matched MeSH terms: Salmonella enterica
Fulltext A scaffolded approach to unearth potential antibacterial components from epicarp of Malaysian Nephelium lappaceum L

Asghar A, Tan YC, Zahoor M, Zainal Abidin SA, Yow YY, Khan E, et al.

Sci Rep, 2021 Jul 05;11(1):13859.
PMID: 34226594 DOI: 10.1038/s41598-021-92622-0

The emergence and spread of antimicrobial resistance have been of serious concern to human health and the management of bacterial infectious diseases. Effective treatment of these diseases requires the development of novel therapeutics, preferably free of side effects. In this regard, natural products are frequently conceived to be potential alternative sources for novel antibacterial compounds. Herein, we have evaluated the antibacterial activity of the epicarp extracts of the Malaysian cultivar of yellow rambutan fruit (Nephelium lappaceum L.) against six pathogens namely, Bacillus subtilis, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella enterica. Among a series of solvent extracts, fractions of ethyl acetate and acetone have revealed significant activity towards all tested strains. Chemical profiling of these fractions, via HPLC, LC-MS and GC-MS, has generated a library of potentially bioactive compounds. Downstream virtual screening, pharmacological prediction, and receptor-ligand molecular dynamics simulation have eventually unveiled novel potential antibacterial compounds, which can be extracted for medicinal use. We report compounds like catechin, eplerenone and oritin-4-beta-ol to be computationally inhibiting the ATP-binding domain of the chaperone, DnaK of P. aeruginosa and MRSA. Thus, our work follows the objective to propose new antimicrobials capable of perforating the barrier of resistance posed by both the gram positives and the negatives.

Matched MeSH terms: Salmonella enterica/drug effects; Salmonella enterica/pathogenicity
Fulltext Genome sequencing and analysis of Salmonella enterica serovar Typhi strain CR0063 representing a carrier individual during an outbreak of typhoid fever in Kelantan, Malaysia

Baddam R, Kumar N, Shaik S, Suma T, Ngoi ST, Thong KL, et al.

Gut Pathog, 2012;4(1):20.
PMID: 23234298 DOI: 10.1186/1757-4749-4-20

Salmonella Typhi is a human restricted pathogen with a significant number of individuals as asymptomatic carriers of the bacterium. Salmonella infection can be effectively controlled if a reliable method for identification of these carriers is developed. In this context, the availability of whole genomes of carrier strains through high- throughput sequencing and further downstream analysis by comparative genomics approaches is very promising. Herein we describe the genome sequence of a Salmonella Typhi isolate representing an asymptomatic carrier individual during a prolonged outbreak of typhoid fever in Kelantan, Malaysia. Putative genomic coordinates relevant in pathogenesis and persistence of this carrier strain are identified and discussed.

Matched MeSH terms: Salmonella enterica
Caenorhabditis elegans-based analysis of Salmonella enterica

Chai-Hoon, K., Jiun-Horng, S., Shiran, M.S., Son, R., Sabrina, S., Noor Zaleha, A.S., et al.

International Food Research Journal, 2010;17(4):845-852.
MyJurnal

Caenorhabditis elegans (C. elegans) have been widely used as an infection model for mammalian related pathogens with promising results. The bacterial factors required for virulence in non-mammalian host C. elegans play a role in mammalian systems. Previous reported that Salmonella found in vegetable and poultry meat could be potential health hazards to human. This study evaluated the pathogenicity of various serovars of Salmonella enterica (S. enterica) that recovered from local indigenous vegetables and poultry meat using C. elegans as a simple host model. Almost all S. enterica isolates were capable of colonizing the intestine of C. elegans, causing a significant reduction in the survival of nematodes. The colonization of Salmonella in C. elegans revealed that the ability of S. enterica in killing C. elegans correlates with its accumulation in the intestine to achieve full pathogenicity. Using this model, the virulence mechanisms of opportunistic pathogenic S. enterica were found to be not only relevant for the interactions of the bacteria with C. elegans but also with mammalian hosts including humans. Hence, C. elegans model could provide valuable insight into preliminary factors from the host that contributes to the environmental bacterial pathogenesis scenario.

Matched MeSH terms: Salmonella enterica
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*
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*
Structural and functional studies of a 50 kDa antigenic protein from Salmonella enterica serovar Typhi

Choong YS, Lim TS, Chew AL, Aziah I, Ismail A

J Mol Graph Model, 2011 Apr;29(6):834-42.
PMID: 21371926 DOI: 10.1016/j.jmgm.2011.01.008

The high typhoid incidence rate in developing and under-developed countries emphasizes the need for a rapid, affordable and accessible diagnostic test for effective therapy and disease management. TYPHIDOT®, a rapid dot enzyme immunoassay test for typhoid, was developed from the discovery of a ∼50 kDa protein specific for Salmonella enterica serovar Typhi. However, the structure of this antigen remains unknown till today. Studies on the structure of this antigen are important to elucidate its function, which will in turn increase the efficiency of the development and improvement of the typhoid detection test. This paper described the predictive structure and function of the antigenically specific protein. The homology modeling approach was employed to construct the three-dimensional structure of the antigen. The built structure possesses the features of TolC-like outer membrane protein. Molecular docking simulation was also performed to further probe the functionality of the antigen. Docking results showed that hexamminecobalt, Co(NH(3))(6)(3+), as an inhibitor of TolC protein, formed favorable hydrogen bonds with D368 and D371 of the antigen. The single point (D368A, D371A) and double point (D368A and D371A) mutations of the antigen showed a decrease (single point mutation) and loss (double point mutations) of binding affinity towards hexamminecobalt. The architecture features of the built model and the docking simulation reinforced and supported that this antigen is indeed the variant of outer membrane protein, TolC. As channel proteins are important for the virulence and survival of bacteria, therefore this ∼50 kDa channel protein is a good specific target for typhoid detection test.

Matched MeSH terms: Salmonella enterica/genetics; Salmonella enterica/metabolism; Salmonella enterica/chemistry*
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*
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
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*
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
Fulltext Potential of fermented papaya beverage in the prevention of foodborne illness incidence

Koh, S.P., Aziz, N., Sharifudin, S.A., Abdullah, R., Hamid, N.S.A., Sarip, J.

Food Research, 2017;1(4):109-113.
MyJurnal

Foodborne illness is recognized as an emerging infectious disease. The incidence of foodborne
infections is common and the majority cases are undiagnosed or unreported. Apart from some
diarrhea or minor gastrointestinal problem, some foodborne pathogenic microbes may cause
death, particularly to those people with weakened immune system. In this study, we have
developed a new fermented papaya beverage using symbiotic culture of yeast and acetic acid
bacteria under controlled biofermentation process. An in-vitro assessment of fermented papaya
beverage against few foodborne pathogenic microorganism was conducted to determine
its minimum bactericidal concentration (MBC>99). Three types of foodborne pathogen:
Escherichia coli O157, Salmonella enterica serovar Typhimurium ATCC 53648, Salmonella
enterica serovar Enteritidis (isolated from infectious chicken) were selected. From minimum
bactericidal concentration (MBC>99) assay, both fermented papaya pulp and leaves beverages
have shown 100% killing rate against three selected foodborne pathogenic microbes. Inversely,
non-fermented papaya pulp and leaves beverages indicated no inhibition at all. In fact, further
dilution of fermented papaya pulp and leaves beverages demonstrated different degree of
MBC>99 and brix value, but the pH value remained less than 3.5. These findings indicated
the combination of soluble solid compounds presents in both fermented papaya beverage and
product acidity play an important role in the inhibition of pathogenic microorganisms. The
preliminary promising results of this work have shown that the great potential of fermented
papaya beverages as a preventive measure to reduce the incidence of foodborne illness.

Matched MeSH terms: Salmonella enterica
A novel antimicrobial peptide derived from fish goose type lysozyme disrupts the membrane of Salmonella enterica

Kumaresan V, Bhatt P, Ganesh MR, Harikrishnan R, Arasu M, Al-Dhabi NA, et al.

Mol Immunol, 2015 Dec;68(2 Pt B):421-33.
PMID: 26477736 DOI: 10.1016/j.molimm.2015.10.001

In aquaculture, accumulation of antibiotics resulted in development of resistance among bacterial pathogens. Consequently, it became mandatory to find alternative to synthetic antibiotics. Antimicrobial peptides (AMPs) which are described as evolutionary ancient weapons have been considered as promising alternates in recent years. In this study, a novel antimicrobial peptide had been derived from goose type lysozyme (LyzG) which was identified from the cDNA library of freshwater fish Channa striatus (Cs). The identified lysozyme cDNA contains 585 nucleotides which encodes a protein of 194 amino acids. CsLyzG was closely related to Siniperca chuatsi with 92.8% homology. The depicted protein sequence contained a GEWL domain with conserved GLMQ motif, 7 active residues and 2 catalytic residues. Gene expression analysis revealed that CsLyzG was distributed in major immune organs with highest expression in head kidney. Results of temporal expression analysis after bacterial (Aeromonas hydrophila) and fungal (Aphanomyces invadans) challenges indicated a stimulant-dependent expression pattern of CsLyzG. Two antimicrobial peptides IK12 and TS10 were identified from CsLyzG and synthesized. Antibiogram showed that IK12 was active against Salmonella enterica, a major multi-drug resistant (MDR) bacterial pathogen which produces beta lactamase. The IK12 induced loss of cell viability in the bacterial pathogen. Flow cytometry assay revealed that IK12 disrupt the membrane of S. enterica which is confirmed by scanning electron microscope (SEM) analysis that reveals blebs around the bacterial cell membrane. Conclusively, CsLyzG is a potential innate immune component and the identified antimicrobial peptide has great caliber to be used as an ecofriendly antibacterial substance in aquaculture.

Matched MeSH terms: Salmonella enterica/drug effects*; Salmonella enterica/metabolism
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
Fulltext Molecular characterization and antimicrobial resistance profiling of Salmonella enterica subsp. enterica isolated from ‘Selom’ (Oenanthe stolonifera)

Learn-Han, L., Yoke-Kqueen, C., Shiran, M.S., Sabrina, S., Noor Zaleha, A.S., Sim, J.H., et al.

International Food Research Journal, 2009;16(2):191-202.
MyJurnal

Fifty-nine isolates of Salmonella enterica subsp. enterica (S. enterica) isolated from indigenous vegetables, ‘selom’ (Oenanthe stolonifera) associated with 13 different serovars were obtained from Chemistry Department of Malaysia. The isolates encompass the common serovar, Salmonella enterica subsp. enterica serovar Weltevreden (S. Weltevreden) (39%) and Salmonella enterica subsp. enterica serovar Agona (S. Agona) (8.5%). Frequencies of the other 11 Salmonella serovars were ranged from 1.7% to 5.1%. All isolates were characterized by Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction (ERIC-PCR), random amplified polymorphic DNA (RAPD), plasmid profiling and antimicrobial susceptibility testing. The results demonstrated ERIC-PCR, RAPD and composite analysis of both are suitable typing methods for S. enterica by demonstrating good discriminative ability and can be utilize as a rapid approach of comparing S. enterica isolates for epidemiological investigation. From this study, ERIC-PCR is exhibited lower discriminatory power when compare with RAPD. On the other hand, plasmid profiles yielded 32 profiles with molecular size ranging from 1129 bp to 17911 bp. Thirteen antimicrobial agents were included in this study and all isolates showed 100% (59/59) resistant to erythromycin and showed Multiple Antimicrobial Resistance (MAR) indexes ranging from 0.08 to 0.68. Dendrogram generated from antimicrobial resistance profiling exhibited poor discriminatory capability at serovar level. Although poultry still remain as the common reservoir for multidrug resistant (MDR) Salmonella. The isolation of 13 Salmonella serovars from selom that showed high MDR in this study is alarming. These results supported the notion that indigenous vegetable (selom) are gaining more antimicrobial resistance and could be potential health hazards.

Matched MeSH terms: Salmonella enterica

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