• 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.

• The Plant Pathology Journal
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• v.37 no.5
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• pp.476-488
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• 2021

Xanthomonas campestris pv. campestris (Xcc) is the causal agent of black rot for cruciferous vegetables worldwide, especially for the cole crops such as cabbage and cauliflower. Due to the lack of resistant cabbage cultivars, black rot has brought about considerable yield losses in recent years in China. Understanding of the pathogen features is a key step for disease prevention, however, the pathogen diversity, population structure, and virulence are largely unknown. In this study, we studied 50 Xcc strains including 39 Xcc isolates collected from cabbage in 20 regions across China, using multilocus sequence genotyping (MLST), repetitive DNA sequence-based PCR (rep-PCR), and pathogenicity tests. For MLST analysis, a total of 12 allelic profiles (AP) were generated, among which the largest AP was AP1 containing 32 strains. Further cluster analysis of rep-PCR divided all strains into 14 DNA groups, with the largest group DNA I comprising of 34 strains, most of which also belonged to AP1. Inoculation tests showed that the representative Xcc strains collected from diverse regions performed differential virulence against three brassica hosts compared with races 1 and 4. Interestingly, these results indicated that AP1/DNA I was not only the main pathotype in China, but also a novel group that differed from the previously reported type races in both genotype and virulence. To our knowledge, this is the first extensive genetic diversity survey for Xcc strains in China, which provides evidence for cabbage resistance breeding and opens the gate for further cabbage-Xcc interaction studies.

• Korean Journal of Veterinary Service
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• v.41 no.3
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• pp.157-163
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• 2018

In order for monitoring of pathogenic bacterial contamination in the freshly slaughtered poultry meats produced in Gyeong-Nam province, we first isolated 4 strains of Salmonella spp. and 32 strains of Enterococcus faecalis from the total 164 samples, then we analyzed potential virulence gene profiles of the bacterial isolates by PCR using species-specific primer. The potential virulence genes we selected in this study were stn, invA, fimA, spvR, and spvC for the isolates of Salmonella spp. and those of esp, cylM, cylA, cylB, gelE, fsrA, fsrB, and fsrC were for the isolates of E. faecalis. The PCR results showed that all 5 virulence genes were detected simultaneously in the all isolates of Salmonella spp. However, there was a diverse occurrence pattern of the virulence genes in the case of E. faecalis. The gene for enterococcal surface protein (esp) was not detected among the isolates (0/32), and the haemolysin gene prevalence rate of cylA, cylB, and cylM were 3.1% (1/32), 9.3% (3/32), and 9.3% (3/32), respectively. Moreover, the genes of gelE, fsrA, fsrB, and fsrC that associated with gelatinase activity were detected in the rate of 53.1% (17/32), 53.1% (17/32), 53.1% (17/32), and 53.1% (17/32), respectively. In conclusion, in the isolates of Salmonella spp., all possessed 5 virulence genes tested, suggesting that they are all related with each other clonally. However, in the case of E. faecalis isolates, the occurrence of the haemolysin genes (cylM, cylA, cylB) and the gelatinase genes (gelE, fsrABC) was highly variable among the isolates.

• KSBB Journal
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• v.28 no.1
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• pp.54-59
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• 2013

Three isolates, E. faecium P1, P2 and P3, from intestinal drugs of three phamaceutical companies, four clinical vancomycin resistant isolates, E. faecium V1, V2, V3 and E. faecalis V4, and three isolates, E. faecalis DW01, DW07 and DW14, from infant feces were tested for the presence of virulence genes, ace, agg, esp, efaA, gelE, sprE, vanA and vanB as well as fsrABC, regulatory genes of gelE and sprE, cylMBA, cytolysin activation genes and cpd, cob and ccf, pheromone genes by PCR and for their phenotype activities such as protease, biofilm formation, cell clumping and hemolysis. The genes encoding cell surface adherence proteins, ace, agg, esp and efaA, were predominantly amplified from the vancomycin resistant strain V4 and the fecal isolates DW01, DW07 and DW14. Both protease and biofilm formation activity were detected only from E. faecalis V4 from which the PCR products of gelE and spreE as well as fsrABC were amplified. The pheromone genes were amplified from the V4, DW01, DW07 and DW14 strains and these strains showed clumping activity. Biofilm formation was observed from the strains DW01, DW07 and DW14, all of which produced PCR products of pheromone, and V4 as well. Whole cytolysin regulator genes were amplified from DW01, DW07 and DW14 and ${\beta}$-hemolysis activity was detected from these strains. Any virulence genes or activities except the pheomone gene ccf were not detected from the pharmaceutical isolates, E. faecium P1, P2 and P3.

• The Plant Pathology Journal
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• v.34 no.2
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• pp.139-142
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• 2018

Pyrenophoratritici-repentis is the causal agent of tan spot. According to their ability to produce necrosis and/or chlorosis on a set of four differential bread wheats, the isolates of this fungus are currently grouped into eight races. When durum wheat genotypes were added to the differential set, a new virulence type was identified in Algeria. The isolates showing this virulence pattern are unable to attack bread wheat while they cause necrosis in durum genotypes. In this work, characterization of those isolates was based on pathological and molecular aspects. This included inoculation of bread and durum wheat, and virulence gene analysis using PCR and sequencing. The results showed that all isolates caused a resistance on all bread wheats of the differential set, while they produced necrosis in durum. ToxA and ToxB genes were amplified in all isolates, whereas toxb was absent. Sequence analysis for both genes showed no differences with those found in the two functional genes. The presence of two genes, ToxA and ToxB, despite the absence of symptoms usually caused by their products, suggests the existence of a new homologous for these two genes yet unknown. The presence of ToxA in the isolate unable to produce necrosis in Glenlea is reported for the first time.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.3
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• pp.301-308
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• 2019

The emergence and spread of multidrug resistant (MDR) Pseudomonas aeruginosa is a critical problem worldwide. The pathogenesis of P. aeruginosa is due partly to the production of several cell-associated and extracellular virulence factors. This study examined the distribution of virulence factors and antimicrobial resistance patterns of carbapenem-resistant P. aeruginosa (CRPA) isolated from a tertiary hospital in Daejeon, Korea. Antimicrobial susceptibility testing was performed using the disk diffusion method, and PCR and DNA sequencing were performed to determine for the presence of virulence genes. In addition, the sequence type (ST) of MDR P. aeruginosa was investigated by multilocus sequence typing (MLST). Among 32 CRPA isolates, 14 (43.8%) were MDR and the major ST was ST235 (10 isolates, 71.4%). All isolates were positive for the presence of virulence genes and the most prevalent virulence genes were toxA, plcN, and phzM (100%). All isolates carried at least eight or more different virulence genes and nine (28.1%) isolates had 15 virulence genes. The presence of the exoU gene was detected in 71.4% of the MDR P. aeruginosa isolates. These results indicate that the presence of the exoU gene can be a predictive marker for the persistence of MDR P. aeruginosa isolates.

• Microbiology and Biotechnology Letters
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• v.47 no.4
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• pp.651-661
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• 2019

Targeting the pathogen viability using drugs is associated with development of drug resistance due to selective pressure. Hence, there is an increased interest in developing agents that target bacterial virulence. In this study, the inhibitory effect of ciclopirox, an antifungal agent with iron chelation potential, on the microbial virulence factors was evaluated in 26 clinical MDR Pseudomonas aeruginosa isolates collected from Alexandria Main University Hospital, a tertiary hospital in Egypt. Treatment with 9 ㎍/ml ciclopirox inhibited the hemolytic activity in 70% isolates, reduced pyocyanin production, decreased protease secretion in 46% isolates, lowered twitching and swarming motility, and decreased biofilm formation by 1.5- to 4.5-fold. The quantitative real-time PCR analysis revealed that treatment with ciclopirox downregulated the expression levels of alkaline protease (aprA) and pyocyanin (phzA1). Ciclopirox is used to treat hematological malignancies and the systemic administration of ciclopirox is reported to have adequate oral absorption with a satisfactory drug safety profile. It is important to calculate the appropriate clinical dose and therapeutic index to reposition ciclopirox from a topical antifungal agent to a promising virulence-modifying agent agent against P. aeruginosa, a problematic Gram-negative pathogen.

• The Plant Pathology Journal
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• v.32 no.3
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• pp.190-200
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• 2016

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial leaf blight (BLB) in rice (Oryza sativa L.). In this study, we investigated the effect of a mutation in opsX (XOO1056), which encodes a saccharide biosynthesis regulatory protein, on the virulence and bacterial chemotaxis of Xoo. We performed DNA micro-array analysis, which showed that 63 of 2,678 genes, including genes related to bacterial motility (flagellar and chemotaxis proteins) were significantly downregulated ($<\;-2\;log_2$ fold changes) by the mutation in opsX. Indeed, motility assays showed that the mutant strain was nonmotile on semisolid agar swarm plates. In addition, a mutant strain (opsX::Tn5) showed decreased virulence against the susceptible rice cultivar, IR24. Quantitative real-time RT-PCR reaction was performed to confirm the expression levels of these genes, including those related to flagella and chemotaxis, in the opsX mutant. Our findings revealed that mutation of opsX affects both virulence and bacterial motility. These results will help to improve our understanding of Xoo and provide insight into Xoo-rice interactions.

• Korean Journal of Veterinary Service
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• v.32 no.2
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• pp.147-153
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• 2009

Salmonella species are the most important etiologic agents of food-borne acute gastroenteritis. The most common serotypes isolated from humans are Salmonella enterica serotype Typhimurium (S. Typhimurium) and S. Enteritidis. Traditional detection methods for Salmonella are based on cultures using selective media and characterization of suspicious colonies by biochemical and serological tests. These methods are generally time-consuming and not so highly sensitive. Recently, the polymerase chain reaction (PCR) has been used as a highly sensitive, specific, and rapid test for the presence of pathogenic bacteria. In this study, a multiplex PCR (m-PCR) was used to detect S. Typhimurium and S. Enteritidis. We selected m-PCR target genes, which were the spv (virulence plasmid specific for S. Enteritidis) and sefA (S. Enteritidis fimbrial antigen) genes, fliC (H1-i antigen specific for S. Typhimurium) and a randomly cloned sequence specific for the genus Salmonella. With m-PCR, random sequence was detected from all strains of Salmonella spp, spv and sefA were detected from all strains of S. Enteritidis (100%), and fliC was detected from all strains of S. Typhimurium (100%). This assay indicate that the specificity of the m-PCR make them potentially valuable tools for detection of S. Typhimurium and S. Enteritidis.

• Proceedings of the Microbiological Society of Korea Conference
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• 2005.05a
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• pp.193.3-193
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• 2005