Displaying publications 1 - 20 of 69 in total

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  1. Fulltext Wide distribution of virulence genes among Enterococcus faecium and Enterococcus faecalis clinical isolates
    Soheili S, Ghafourian S, Sekawi Z, Neela V, Sadeghifard N, Ramli R, et al.
    ScientificWorldJournal, 2014;2014:623174.
    PMID: 25147855 DOI: 10.1155/2014/623174
    Enterococcus, a Gram-positive facultative anaerobic cocci belonging to the lactic acid bacteria of the phylum Firmicutes, is known to be able to resist a wide range of hostile conditions such as different pH levels, high concentration of NaCl (6.5%), and the extended temperatures between 5(°)C and 65(°)C. Despite being the third most common nosocomial pathogen, our understanding on its virulence factors is still poorly understood. The current study was aimed to determine the prevalence of different virulence genes in Enterococcus faecalis and Enterococcus faecium. For this purpose, 79 clinical isolates of Malaysian enterococci were evaluated for the presence of virulence genes. pilB, fms8, efaAfm, and sgrA genes are prevalent in all clinical isolates. In conclusion, the pathogenicity of E. faecalis and E. faecium could be associated with different virulence factors and these genes are widely distributed among the enterococcal species.
    Matched MeSH terms: Virulence Factors/genetics*
  2. Fulltext Whole-genome comparative analysis of Malaysian Burkholderia pseudomallei clinical isolates
    Ghazali AK, Eng SA, Khoo JS, Teoh S, Hoh CC, Nathan S
    Microb Genom, 2021 02;7(2).
    PMID: 33565959 DOI: 10.1099/mgen.0.000527
    Burkholderia pseudomallei, a soil-dwelling Gram-negative bacterium, is the causative agent of the endemic tropical disease melioidosis. Clinical manifestations of B. pseudomallei infection range from acute or chronic localized infection in a single organ to fulminant septicaemia in multiple organs. The diverse clinical manifestations are attributed to various factors, including the genome plasticity across B. pseudomallei strains. We previously characterized B. pseudomallei strains isolated in Malaysia and noted different levels of virulence in model hosts. We hypothesized that the difference in virulence might be a result of variance at the genome level. In this study, we sequenced and assembled four Malaysian clinical B. pseudomallei isolates, UKMR15, UKMPMC2000, UKMD286 and UKMH10. Phylogenomic analysis showed that Malaysian subclades emerged from the Asian subclade, suggesting that the Malaysian strains originated from the Asian region. Interestingly, the low-virulence strain, UKMH10, was the most distantly related compared to the other Malaysian isolates. Genomic island (GI) prediction analysis identified a new island of 23 kb, GI9c, which is present in B. pseudomallei and Burkholderia mallei, but not Burkholderia thailandensis. Genes encoding known B. pseudomallei virulence factors were present across all four genomes, but comparative analysis of the total gene content across the Malaysian strains identified 104 genes that are absent in UKMH10. We propose that these genes may encode novel virulence factors, which may explain the reduced virulence of this strain. Further investigation on the identity and role of these 104 proteins may aid in understanding B. pseudomallei pathogenicity to guide the design of new therapeutics for treating melioidosis.
    Matched MeSH terms: Virulence Factors/genetics
  3. 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: Virulence Factors/genetics*
  4. Fulltext Virulence Factors and Antibiotic Susceptibility of Staphylococcus aureus Isolates in Ready-to-Eat Foods: Detection of S. aureus Contamination and a High Prevalence of Virulence Genes
    Puah SM, Chua KH, Tan JA
    Int J Environ Res Public Health, 2016 Feb;13(2):199.
    PMID: 26861367 DOI: 10.3390/ijerph13020199
    Staphylococcus aureus is one of the leading causes of food poisoning. Its pathogenicity results from the possession of virulence genes that produce different toxins which result in self-limiting to severe illness often requiring hospitalization. In this study of 200 sushi and sashimi samples, S. aureus contamination was confirmed in 26% of the food samples. The S. aureus isolates were further characterized for virulence genes and antibiotic susceptibility. A high incidence of virulence genes was identified in 96.2% of the isolates and 20 different virulence gene profiles were confirmed. DNA amplification showed that 30.8% (16/52) of the S. aureus carried at least one SE gene which causes staphylococcal food poisoning. The most common enterotoxin gene was seg (11.5%) and the egc cluster was detected in 5.8% of the isolates. A combination of hla and hld was the most prevalent coexistence virulence genes and accounted for 59.6% of all isolates. Antibiotic resistance studies showed tetracycline resistance to be the most common at 28.8% while multi-drug resistance was found to be low at 3.8%. In conclusion, the high rate of S. aureus in the sampled sushi and sashimi indicates the need for food safety guidelines.
    Matched MeSH terms: Virulence Factors/genetics*
  5. Transcriptome analysis of Burkholderia pseudomallei SCV reveals an association with virulence, stress resistance and intracellular persistence
    Al-Maleki AR, Vellasamy KM, Mariappan V, Venkatraman G, Tay ST, Vadivelu J
    Genomics, 2020 01;112(1):501-512.
    PMID: 30980902 DOI: 10.1016/j.ygeno.2019.04.002
    Differences in expression of potential virulence and survival genes were associated with B. pseudomallei colony morphology variants. Microarray was used to investigate B. pseudomallei transcriptome alterations among the wild type and small colony variant (SCV) pre- and post-exposed to A549 cells. SCV pre- and post-exposed have lower metabolic requirements and consume lesser energy than the wild type pre- and post-exposed to A549. However, both the wild type and SCV limit their metabolic activities post- infection of A549 cells and this is indicated by the down-regulation of genes implicated in the metabolism of amino acids, carbohydrate, lipid, and other amino acids. Many well-known virulence and survival factors, including T3SS, fimbriae, capsular polysaccharides and stress response were up-regulated in both the wild type and SCV pre- and post-exposed to A549 cells. Microarray analysis demonstrated essential differences in bacterial response associated with virulence and survival pre- and post-exposed to A549 cells.
    Matched MeSH terms: Virulence Factors/genetics
  6. The re-emerging of orf virus infection: A call for surveillance, vaccination and effective control measures
    Bala JA, Balakrishnan KN, Abdullah AA, Mohamed R, Haron AW, Jesse FFA, et al.
    Microb Pathog, 2018 Jul;120:55-63.
    PMID: 29709684 DOI: 10.1016/j.micpath.2018.04.057
    Orf disease is known to be enzootic among small ruminants in Asia, Africa, and some other parts of the world. The disease caused by orf virus is highly contagious among small ruminant species. Unfortunately, it has been neglected for decades because of the general belief that it only causes a self-limiting disease. On the other hand, in the past it has been reported to cause huge cumulative financial losses in livestock farming. Orf disease is characterized by localized proliferative and persistent skin nodule lesions that can be classified into three forms: generalized, labial and mammary or genitals. It can manifest as benign or malignant types. The later type of orf can remain persistent, often fatal and usually causes a serious outbreak among small ruminant population. Morbidity and mortality rates of orf are higher especially in newly infected kids and lambs. Application of antibiotics together with antipyretic and/or analgesic is highly recommended as a supportive disease management strategy for prevention of subsequent secondary microbial invasion. The presence of various exotic orf virus strains of different origin has been reported in many countries mostly due to poorly controlled cross-border virus transmission. There have been several efforts to develop orf virus vaccines and it was with variable success. The use of conventional vaccines to control orf is a debatable topic due to the concern of short term immunity development. Following re-infection in previously vaccinated animals, it is uncommon to observe the farms involved to experience rapid virus spread and disease outbreak. Meanwhile, cases of zoonosis from infected animals to animal handler are not uncommon. Despite failures to contain the spread of orf virus by the use of conventional vaccines, vaccination of animals with live orf virus is still considered as one of the best choice. The review herein described pertinent issues with regard to the development and use of potential effective vaccines as a control measure against orf virus infection.
    Matched MeSH terms: Virulence Factors/genetics
  7. The cag PAI is intact and functional but HP0521 varies significantly in Helicobacter pylori isolates from Malaysia and Singapore
    Schmidt HM, Andres S, Nilsson C, Kovach Z, Kaakoush NO, Engstrand L, et al.
    Eur J Clin Microbiol Infect Dis, 2010 Apr;29(4):439-51.
    PMID: 20157752 DOI: 10.1007/s10096-010-0881-7
    Helicobacter pylori-related disease is at least partially attributable to the genotype of the infecting strain, particularly the presence of specific virulence factors. We investigated the prevalence of a novel combination of H. pylori virulence factors, including the cag pathogenicity island (PAI), and their association with severe disease in isolates from the three major ethnicities in Malaysia and Singapore, and evaluated whether the cag PAI was intact and functional in vitro. Polymerase chain reaction (PCR) was used to detect dupA, cagA, cagE, cagT, cagL and babA, and to type vacA, the EPIYA motifs, HP0521 alleles and oipA ON status in 159 H. pylori clinical isolates. Twenty-two strains were investigated for IL-8 induction and CagA translocation in vitro. The prevalence of cagA, cagE, cagL, cagT, babA, oipA ON and vacA s1 and i1 was >85%, irrespective of the disease state or ethnicity. The prevalence of dupA and the predominant HP0521 allele and EPIYA motif varied significantly with ethnicity (p < 0.05). A high prevalence of an intact cag PAI was found in all ethnic groups; however, no association was observed between any virulence factor and disease state. The novel association between the HP0521 alleles, EPIYA motifs and host ethnicity indicates that further studies to determine the function of this gene are important.
    Matched MeSH terms: Virulence Factors/genetics*
  8. Fulltext The Conserved Molecular Determinants of Virulence in Dengue Virus
    Ahmad Z, Poh CL
    Int J Med Sci, 2019;16(3):355-365.
    PMID: 30911269 DOI: 10.7150/ijms.29938
    Dengue virus belongs to the Flaviviridae family which also includes viruses such as the Zika, West Nile and yellow fever virus. Dengue virus generally causes mild disease, however, more severe forms of the dengue virus infection, dengue haemorrhagic fever (DHF) and dengue haemorrhagic fever with shock syndrome (DSS) can also occur, resulting in multiple organ failure and even death, especially in children. The only dengue vaccine available in the market, CYD-TDV offers limited coverage for vaccinees from 9-45 years of age and is only recommended for individuals with prior dengue exposure. A number of mutations that were shown to attenuate virulence of dengue virus in vitro and/or in vivo have been identified in the literature. The mutations which fall within the conserved regions of all four dengue serotypes are discussed. This review hopes to provide information leading to the construction of a live attenuated dengue vaccine that is suitable for all ages, irrespective of the infecting dengue serotype and prior dengue exposure.
    Matched MeSH terms: Virulence Factors/genetics
  9. Fulltext Single-molecule sequencing reveals the molecular basis of multidrug-resistance in ST772 methicillin-resistant Staphylococcus aureus
    Steinig EJ, Andersson P, Harris SR, Sarovich DS, Manoharan A, Coupland P, et al.
    BMC Genomics, 2015;16:388.
    PMID: 25981586 DOI: 10.1186/s12864-015-1599-9
    Methicillin-resistant Staphylococcus aureus (MRSA) is a major cause of hospital-associated infection, but there is growing awareness of the emergence of multidrug-resistant lineages in community settings around the world. One such lineage is ST772-MRSA-V, which has disseminated globally and is increasingly prevalent in India. Here, we present the complete genome sequence of DAR4145, a strain of the ST772-MRSA-V lineage from India, and investigate its genomic characteristics in regards to antibiotic resistance and virulence factors.
    Matched MeSH terms: Virulence Factors/genetics
  10. Fulltext Rosmarinic acid exhibits broad anti-enterovirus A71 activity by inhibiting the interaction between the five-fold axis of capsid VP1 and cognate sulfated receptors
    Hsieh CF, Jheng JR, Lin GH, Chen YL, Ho JY, Liu CJ, et al.
    Emerg Microbes Infect, 2020 Dec;9(1):1194-1205.
    PMID: 32397909 DOI: 10.1080/22221751.2020.1767512
    Enterovirus A71 (EV-A71), a positive-stranded RNA virus of the Picornaviridae family, may cause neurological complications or fatality in children. We examined specific factors responsible for this virulence using a chemical genetics approach. Known compounds from an anti-EV-A71 herbal medicine, Salvia miltiorrhiza (Danshen), were screened for anti-EV-A71. We identified a natural product, rosmarinic acid (RA), as a potential inhibitor of EV-A71 by cell-based antiviral assay and in vivo mouse model. Results also show that RA may affect the early stage of viral infection and may target viral particles directly, thereby interfering with virus-P-selectin glycoprotein ligand-1 (PSGL1) and virus-heparan sulfate interactions without abolishing the interaction between the virus and scavenger receptor B2 (SCARB2). Sequencing of the plaque-purified RA-resistant viruses revealed a N104K mutation in the five-fold axis of the structural protein VP1, which contains positively charged amino acids reportedly associated with virus-PSGL1 and virus-heparan sulfate interactions via electrostatic attraction. The plasmid-derived recombinant virus harbouring this mutation was confirmed to be refractory to RA inhibition. Receptor pull-down showed that this non-positively charged VP1-N104 is critical for virus binding to heparan sulfate. As the VP1-N104 residue is conserved among different EV-A71 strains, RA may be useful for inhibiting EV-A71 infection, even for emergent virus variants. Our study provides insight into the molecular mechanism of virus-host interactions and identifies a promising new class of inhibitors based on its antiviral activity and broad spectrum effects against a range of EV-A71.
    Matched MeSH terms: Virulence Factors/genetics
  11. Role of Helicobacter pylori virulence factor and genotypes in non-ulcer dyspepsia
    Tan HJ, Rizal AM, Rosmadi MY, Goh KL
    J Gastroenterol Hepatol, 2006 Jan;21(1 Pt 1):110-5.
    PMID: 16706821
    The role of Helicobacter pylori (HP) in non-ulcer dyspepsia is debatable. Eradicating HP will help a small group of non-ulcer dyspeptic patients. However, it is unclear which subgroup of patients will benefit from eradication therapy. The aim of the present study was to compare the cagA and cagE status, as well as vacA genotypes, of HP in non-ulcer dyspeptic patients who responded successfully to eradication therapy compared with those patients who did not.
    Matched MeSH terms: Virulence Factors/genetics*
  12. Fulltext Prevalence, antimicrobial susceptibility and virulotyping of Listeria species and Listeria monocytogenes isolated from open-air fish markets
    Jamali H, Paydar M, Ismail S, Looi CY, Wong WF, Radmehr B, et al.
    BMC Microbiol, 2015;15:144.
    PMID: 26209099 DOI: 10.1186/s12866-015-0476-7
    The aim of this study was to investigate the prevalence and characterization of Listeria species and Listeria monocytogenes isolated from raw fish and open-air fish market environments. Eight hundred and sixty two samples including raw fish and fish market environments (samples from workers' hands, workers' knives, containers and work surface) were collected from the open-air fish markets in the Northern region of Iran.
    Matched MeSH terms: Virulence Factors/genetics
  13. Fulltext Prevalence of ST9 methicillin-resistant Staphylococcus aureus among pigs and pig handlers in Malaysia
    Neela V, Mohd Zafrul A, Mariana NS, van Belkum A, Liew YK, Rad EG
    J Clin Microbiol, 2009 Dec;47(12):4138-40.
    PMID: 19812280 DOI: 10.1128/JCM.01363-09
    Methicillin-resistant Staphylococcus aureus (MRSA) of sequence type 398 (ST398) has frequently been detected in pigs and pig handlers. However, in Malaysia, sampling 360 pigs and 90 pig handlers from 30 farms identified novel ST9-spa type t4358-staphylococcal cassette chromosome mec type V MRSA strains that were found to transiently colonize more than 1% of pigs and 5.5% of pig handlers.
    Matched MeSH terms: Virulence Factors/genetics
  14. Prevalence of Helicobacter pylori cagA, babA2, and dupA genotypes and correlation with clinical outcome in Malaysian patients with dyspepsia
    Osman HA, Hasan H, Suppian R, Hassan S, Andee DZ, Abdul Majid N, et al.
    Turk J Med Sci, 2015;45(4):940-6.
    PMID: 26422871
    BACKGROUND/AIM: The severity of disease outcome in dyspepsia has been attributed to Helicobacter pylori virulence genes. The aim of this study was to determine the distribution of H. pylori virulence genes (cagA, babA2, and dupA) and to determine whether or not there arises a significant correlation with clinical dyspepsia outcomes.

    MATERIALS AND METHODS: H. pylori genotypes cagA, babA2, and dupA were identified by polymerase chain reactions from gastric biopsy samples in 105 H. pylori-positive patients.

    RESULTS: The positive rates for cagA, babA2, and dupA genes in H. pylori dyspeptic patients were 69.5%, 41.0%, and 22.9%, respectivel cagA was more prevalent in Indians (39.7%), babA2 was more prevalent in Malays (39.5%), and dupA detection occurred more frequently in both Indians and Malays and at the same rate (37.5%). The Chinese inhabitants had the lowest prevalence of the three genes. Nonulcer disease patients had a significantly higher distribution of cagA (76.7%), babA2 (74.4%), and dupA (75.0%). There was no apparent association between these virulence genes and the clinical outcomes.

    CONCLUSION: The lower prevalence of these genes and variations among different ethnicities implies that the strains are geographically and ethnically dependent. None of the virulence genes were knowingly beneficial in predicting the clinical outcome of H. pylori infection in our subjects.

    Matched MeSH terms: Virulence Factors/genetics*
  15. Fulltext Predominance of ST22-MRSA-IV Clone and Emergence of Clones for Methicillin-Resistant Staphylococcus aureus Clinical Isolates Collected from a Tertiary Teaching Hospital Over a Two-Year Period
    Niek WK, Teh CSJ, Idris N, Thong KL, Ponnampalavanar S
    Jpn J Infect Dis, 2019 Jul 24;72(4):228-236.
    PMID: 30814457 DOI: 10.7883/yoken.JJID.2018.289
    Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common nosocomial pathogens, causing mild to severe infections. This study aimed to determine the genotypic and phenotypic characteristics of clinical MRSA isolates collected from a teaching hospital from 2014 - 2015. These isolates were genotyped by multilocus sequence typing, staphylococcal cassette chromosomal mec (SCCmec) typing, virulence genes detection, and pulsed-field gel electrophoresis; they were phenotyped based on their antibiotics susceptibility profiles. The most prevalent sequence type was ST22. ST3547 was identified from a blood isolate from 2015. Three SCCmec types (III in 26.26%, IV in 70.71%, and V in 3.03% isolates) were detected. Agr type I, II, and III were also detected among the isolates. The most prevalent virulence genes found were hemolysin (100%) and intracellular adhesion (91.9%). At least one staphylococcal enterotoxin was detected in 83 (83.8%) isolates. All the isolates were susceptible to vancomycin (minimum inhibitory concentration ≤ 2 μg/mL). Statistical analysis revealed a significant increase in hypertension (p = 0.035), dyslipidemia and obesity (p = 0.046), and previous exposure to any quinolone (p = 0.010) cases over the two-year period. The emergence and circulation of community-associated MRSA variants were observed in our hospital.
    Matched MeSH terms: Virulence Factors/genetics
  16. Fulltext Predominance and emergence of clones of hospital-acquired methicillin-resistant Staphylococcus aureus in Malaysia
    Ghaznavi-Rad E, Nor Shamsudin M, Sekawi Z, Khoon LY, Aziz MN, Hamat RA, et al.
    J Clin Microbiol, 2010 Mar;48(3):867-72.
    PMID: 20089756 DOI: 10.1128/JCM.01112-09
    We define the epidemiology of predominant and sporadic methicillin-resistant Staphylococcus aureus (MRSA) strains in a central teaching and referral hospital in Kuala Lumpur, Malaysia. This is done on the basis of spa sequencing, multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) typing, and virulence gene profiling. During the period of study, the MRSA prevalence was 44.1%, and 389 MRSA strains were included. The prevalence of MRSA was found to be significantly higher in the patients of Indian ethnicity (P < 0.001). The majority (92.5%) of the isolates belonged to ST-239, spa type t037, and possessed the type III or IIIA SCCmec. The arginine catabolic mobile element (ACME) arcA gene was detected in three (1.05%) ST-239 isolates. We report the first identification of ACME arcA gene-positive ST-239. Apart from this predominant clone, six (1.5%) isolates of ST-22, with two related spa types (t032 and t4184) and a singleton (t3213), carrying type IVh SCCmec, were detected for the first time in Asia. A limited number of community-acquired (CA) MRSA strains were also detected. These included ST-188/t189 (2.1%), ST-1/t127 (2.3%), and ST-7/t091 (1%). Panton-Valentin leukocidin (PVL) was detected in all ST-1 and ST-188 strains and in 0.7% of the ST-239 isolates. The majority of the isolates carried agr I, except that ST-1 strains were agr III positive. Virulence genes seg and sei were seen only among ST-22 isolates. In conclusion, current results revealed the predominance of ST-239-SCCmec III/IIIA and the penetration of ST-22 with different virulence gene profiles. The emergence in Malaysia of novel clones of known epidemic and pathogenic potential should be taken seriously.
    Matched MeSH terms: Virulence Factors/genetics
  17. Fulltext Phylogeny and putative virulence gene analysis of Bartonella bovis
    Tay ST, Kho KL, Lye SF, Ngeow YF
    J Vet Med Sci, 2018 Apr 18;80(4):653-661.
    PMID: 29311425 DOI: 10.1292/jvms.17-0448
    Bartonella bovis is a small Gram-negative bacterium recognized as an etiological agent for bacteremia and endocarditis in cattle. As few reports are available on the taxonomic position of B. bovis and its mechanism of virulence, this study aims to resolve the phylogeny of B. bovis and investigate putative virulence genes based on whole genome sequence analysis. Genome-wide comparisons based on single nucleotide polymorphisms (SNP) and orthologous genes were performed in this study for phylogenetic inference of 27 Bartonella species. Rapid Annotation using Subsystem Technology (RAST) analysis was used for annotation of putative virulence genes. The phylogenetic tree generated from the genome-wide comparison of orthologous genes exhibited a topology almost similar to that of the tree generated from SNP-based comparison, indicating a high concordance in the nucleotide and amino acid sequences of Bartonella spp. The analyses show consistent grouping of B. bovis in a cluster related to ruminant-associated species, including Bartonella australis, Bartonella melophagi and Bartonella schoenbuchensis. RAST analysis revealed genes encoding flagellar components, in corroboration with the observation of flagella-like structure of BbUM strain under negative straining. Genes associated with virulence, disease and defence, prophages, membrane transport, iron acquisition, motility and chemotaxis are annotated in B. bovis genome. The flagellin (flaA) gene of B. bovis is closely related to Bartonella bacilliformis and Bartonella clarridgeiae but distinct from other Gram-negative bacteria. The absence of type IV secretion systems, the bona fide pathogenicity factors of bartonellae, in B. bovis suggests that it may have a different mechanism of pathogenicity.
    Matched MeSH terms: Virulence Factors/genetics*
  18. Fulltext Phenotypic and genomic characterization of a Vibrio parahaemolyticus strain causing disease in Penaeus vannamei provides insights into its niche adaptation and pathogenic mechanism
    Zhang X, Sun J, Chen F, Qi H, Chen L, Sung YY, et al.
    Microb Genom, 2021 05;7(5).
    PMID: 33952389 DOI: 10.1099/mgen.0.000549
    The virulence of Vibrio parahaemolyticus is variable depending on its virulence determinants. A V. parahaemolyticus strain, in which the virulence is governed by the pirA and pirB genes, can cause acute hepatopancreatic necrosis disease (AHPND) in shrimps. Some V. parahaemolyticus that are non-AHPND strains also cause shrimp diseases and result in huge economic losses, while their pathogenicity and pathogenesis remain unclear. In this study, a non-AHPND V. parahaemolyticus, TJA114, was isolated from diseased Penaeus vannamei associated with a high mortality. To understand its virulence and adaptation to the external environment, whole-genome sequencing of this isolate was conducted, and its phenotypic profiles including pathogenicity, growth characteristics and nutritional requirements were investigated. Shrimps following artificial infection with this isolate presented similar clinical symptoms to the naturally diseased ones and generated obvious pathological lesions. The growth characteristics indicated that the isolate TJA114 could grow well under different salinity (10-55 p.p.t.), temperature (23-37 °C) and pH (6-10) conditions. Phenotype MicroArray results showed that this isolate could utilize a variety of carbon sources, amino acids and a range of substrates to help itself adapt to the high hyperosmotic and alkaline environments. Antimicrobial-susceptibility test showed that it was a multidrug-resistant bacterium. The whole-genomic analysis showed that this V. parahaemolyticus possessed many important functional genes associated with multidrug resistance, stress response, adhesions, haemolysis, putative secreted proteases, dedicated protein secretion systems and a variety of nutritional metabolic mechanisms. These annotated functional genes were confirmed by the phenotypic profiles. The results in this study indicated that this V. parahaemolyticus isolate possesses a high pathogenicity and strong environmental adaptability.
    Matched MeSH terms: Virulence Factors/genetics
  19. 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: Virulence Factors/genetics
  20. Occurrence of Enterococcus species with virulence markers in an urban flow-influenced tropical recreational beach
    Ahmad A, Dada AC, Usup G, Heng LY
    Mar Pollut Bull, 2014 May 15;82(1-2):26-38.
    PMID: 24725825 DOI: 10.1016/j.marpolbul.2014.03.028
    Median enterococci counts of beach water samples gradually increased at statistically significant levels (χ2: 26.53, df: 4; p<0.0001) with increasing proximity to river influx. The difference in proportion of antibiotic resistant enterococci in beach water and river water samples was statistically significant (p<0.05) for the tested antibiotics with river isolates generally presenting higher resistance frequencies. Virulence genes cyl, esp, gelE and asa were detected at varying frequencies (7.32%, 21.95%, 100% and 63.41% respectively) among river isolates. On the other hand, the prevalence of these genes was lower (0%, 20%, 67.27% and 41.82% respectively) among beach water isolates. Multi-Locus-Sequence-Typing analysis of Enterococcus faecalis presented four sequence types (ST) one of which shared six out of seven tested loci with ST6, a member of the clonal complex of multi-drug resistant strains associated with hospital outbreaks.
    Matched MeSH terms: Virulence Factors/genetics*
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