• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2005.06a
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• pp.264-265
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• 2005

• Journal of Veterinary Science
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• v.24 no.6
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• pp.82.1-82.12
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• 2023

Background: The current conventional serotyping based on antigen-antisera agglutination could not provide a better understanding of the potential pathogenicity of Salmonella enterica subsp. enterica serovar Brancaster. Surveillance data from Malaysian poultry farms indicated an increase in its presence over the years. Objective: This study aims to investigate the virulence determinants and antimicrobial resistance in S. Brancaster isolated from chickens in Malaysia. Methods: One hundred strains of archived S. Brancaster isolated from chicken cloacal swabs and raw chicken meat from 2017 to 2022 were studied. Two sets of multiplex polymerase chain reaction (PCR) were conducted to identify eight virulence genes associated with pathogenicity in Salmonella (invasion protein gene [invA], Salmonella invasion protein gene [sipB], Salmonella-induced filament gene [sifA], cytolethal-distending toxin B gene [cdtB], Salmonella iron transporter gene [sitC], Salmonella pathogenicity islands gene [spiA], Salmonella plasmid virulence gene [spvB], and inositol phosphate phosphatase gene [sopB]). Antimicrobial susceptibility assessment was conducted by disc diffusion method on nine selected antibiotics for the S. Brancaster isolates. S. Brancaster, with the phenotypic ACSSuT-resistance pattern (ampicillin, chloramphenicol, streptomycin, sulphonamides, and tetracycline), was subjected to PCR to detect the corresponding resistance gene(s). Results: Virulence genes detected in S. Brancaster in this study were invA, sitC, spiA, sipB, sopB, sifA, cdtB, and spvB. A total of 36 antibiogram patterns of S. Brancaster with a high level of multidrug resistance were observed, with ampicillin exhibiting the highest resistance. Over a third of the isolates displayed ACSSuT-resistance, and seven resistance genes (β-lactamase temoneira [bla_TEM], florfenicol/chloramphenicol resistance gene [floR], streptomycin resistance gene [strA], aminoglycoside nucleotidyltransferase gene [ant(3")-Ia], sulfonamides resistance gene [sul-1, sul-2], and tetracycline resistance gene [tetA]) were detected. Conclusion: Multidrug-resistant S. Brancaster from chickens harbored an array of virulence-associated genes similar to other clinically significant and invasive non-typhoidal Salmonella serovars, placing it as another significant foodborne zoonosis.

• Microbiology and Biotechnology Letters
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• v.51 no.4
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• pp.390-402
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• 2023

Salmonella are Gram-negative pathogenic bacteria commonly found in food animals such as poultry and swine and potentially constitute risks and threats to food safety and public health through transmissible virulence and antimicrobial resistance (AMR) genes. Although there are previous studies in the Philippines regarding genotypic and phenotypic AMR in Salmonella, there are very few on virulence and their associations. Hence, this study collected 700 Salmonella isolates from swine samples in abattoirs and wet markets among four districts in Metro Manila and characterized their genotypic virulence and β-lactam AMR profiles. Gene frequency patterns and statistical associations between virulence and bla genes and comparisons based on location types (abattoirs and wet markets) and districts were also determined. High prevalence (>50%) of virulence genes was detected encompassing Salmonella pathogenicity islands (SPIs) 1-5 suggesting their pathogenic potential, but none possessed plasmid-borne virulence genes spvR and spvC. For bla, bla_TEM was detected with high prevalence (>45%) and revealed significant associations to four SPI genes, namely, avrA, hilA, mgtC, and spi4R, which suggest high resistance potential particularly to β-lactam antibiotics and relationships with pathogenicity that remain mechanistically unestablished until now. Lastly, comparisons of location types and districts showed variations in gene prevalence suggesting effects from environmental factors throughout the swine production chain. This study provides vital data on the genotypic virulence and AMR of Salmonella from swine in abattoirs and wet markets that suggest their pathogenicity and resistance potential for policymakers to implement enforced surveillance and regulations for the improvement of the Philippine swine industry.

• Microbiology and Biotechnology Letters
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• v.40 no.1
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• pp.70-75
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• 2012

In Salmonella enterica, many genes encoded within Salmonella pathogenicity islands (SPI) 1 and 2 are required to cause a range of diseases in a variety of hosts. The SPI1-encoded regulator HilD activates both the SPI1 and 2 genes at different times during growth in Luria-Bertani (LB) media. In this study, the expression levels of hilD during growth in LB were investigated. The data suggest that hilD expression is induced in the early stationary phase and decreases in the late stationary phase, when sseA, an SPI2 gene, is maximally expressed. However, HilD could act as an activator of sseA expression in the late stationary phase despite being present at low levels. SseA expression was investigated in SPI1 regulator mutant strains, hilA, hilD and invF mutants. As expected, hilD mutation decreased sseA expression. However, we found that invF mutation caused a 1.5-fold increase in sseA expression in not only LB but also M9 minimal media, which is thought to resemble an intracellular environment. InvF overexpression restored sseA expression to wild-type levels in an invF mutant but did not cause an additional reduction in sseA expression. These results suggest that SPI1 controls SPI2 expression either positively or negatively.

• Journal of Microbiology and Biotechnology
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• v.27 no.11
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• pp.1983-1993
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• 2017

Salmonella enterica subsp. enterica serovar Typhimurium, one of the most common foodborne pathogens, is transmitted mainly through contaminated food derived from infected animals. In this study, S. Typhimurium ST1120, an isolate from pig feces in Korea, was subjected to whole-genome analysis to understand its genomic features associated with virulence. The genome of ST1120 was found to have a circular chromosome of 4,855,001 bp (GC content 52.2%) and a plasmid of 6,863 bp (GC content 46.0%). This chromosome was predicted to have 4,558 open reading frames (ORFs), 17 pseudogenes, 22 rRNA genes, and 86 tRNA genes. Its plasmid was predicted to have three ORFs. Comparative genome analysis revealed that ST1120 was phylogenetically close to S. Typhimurium U288, a critical isolate in piggery farms and food chains in Europe. In silico functional analysis predicted that the ST1120 genome harbored multiple genes associated with virulence and stress resistance, including Salmonella pathogenicity islands (SPIs containing SPI-1 to SPI-5, SPI-13, and SPI-14), C63PI locus, ST104 prophage locus, and various antibiotic resistance genes. In accordance with these analysis results, ST1120 showed competence in invasion and survival abilities when it was added to host cells. It also exhibited robust resistance against antibiotics in comparison with other S. Typhimurium strains. This is the first report of the complete genome sequence of S. Typhimurium isolated from swine in Korea. Comparative genome analysis between ST1120 and other Salmonella strains would provide fruitful information toward understanding Salmonella host specificity and developing control measures against S. Typhimurium infection.

• Microbiology and Biotechnology Letters
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• v.47 no.2
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• pp.310-316
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• 2019

Distribution of Salmonella enterica serovars and their associated virulence determinants is wide-spread among food animals, which are continuously implicated in periodic salmonellosis outbreaks globally. The aim of this study was to determine and evaluate the diversity of five Salmonella serovar virulence genes (invA, pefA, cdtB, spvC and iroN) isolated from food animals and humans. Using standard microbiological techniques, Salmonella spp. were isolated from the feces of humans and three major food animals. Virulence determinants of the isolates were assayed using PCR. Clonal relatedness of the dominant serovar was determined via pulsed-field gel electrophoresis (PFGE) using the restriction enzyme, Xbal. Seventy one Salmonella spp. were isolated and serotyped into 44 serovars. Non-typhoidal Salmonella (NTS; 68) accounted for majority (95.8%) of the Salmonella serovars. Isolates from chicken (34) accounted for 47.9% of all isolates, out of which S. Budapest (14) was predominant (34.8%). However, the dominant S. Budapest serovars showed no genetic relatedness. The invA gene located on SPI-1 was detected in all isolates. Furthermore, 94% of the isolates from sheep harbored the spvC genes. The iroN gene was present in 50%, 100%, 88%, and 91% of isolates from human, chicken, sheep, and cattle, respectively. The pefA gene was detected in 18 isolates from chicken and a single isolate from sheep. Notably, having diverse Salmonella serovars containing plasmid encoded virulence genes circulating the food chain is of public health significance; hence, surveillance is required.

• The Plant Pathology Journal
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• v.38 no.1
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• pp.12-24
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• 2022

In this study, we conducted whole-genome sequencing with six species of Pectobacterium composed of seven strains, JR1.1, BP201601.1, JK2.1, HNP201719, MYP201603, PZ1, and HC, for the analysis of pathogenic factors associated with the genome of Pectobacterium. The genome sizes ranged from 4,724,337 bp to 5,208,618 bp, with the GC content ranging from 50.4% to 52.3%. The average nucleotide identity was 98% among the two Pectobacterium species and ranged from 88% to 96% among the remaining six species. A similar distribution was observed in the carbohydrate-active enzymes (CAZymes) class and extracellular plant cell wall degrading enzymes (PCWDEs). HC showed the highest number of enzymes in CAZymes and the lowest number in the extracellular PCWDEs. Six strains showed four subsets, and HC demonstrated three subsets, except hasDEF, in type I secretion system, while the type II secretion system of the seven strains was conserved. Components of human pathogens, such as Salmonella pathogenicity island 1 type type III secretion system (T3SS) and effectors, were identified in PZ1; T3SSa was not identified in HC. Two putative effectors, including hrpK, were identified in seven strains along with dspEF. We also identified 13 structural genes, six regulator genes, and five accessory genes in the type VI secretion system (T6SS) gene cluster of six Pectobacterium species, along with the loss of T6SS in PZ1. HC had two subsets, and JK2.1 had three subsets of T6SS. With the GxSxG motif, the phospholipase A gene did locate among tssID and duf4123 genes in the T6SSa cluster of all strains. Important domains were identified in the vgrG/paar islands, including duf4123, duf2235, vrr-nuc, and duf3396.