Displaying publications 21 - 29 of 29 in total

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  1. Lim KT, Hanifah YA, Mohd Yusof MY, Thong KL
    Trop Biomed, 2012 Jun;29(2):212-9.
    PMID: 22735842 MyJurnal
    Staphylococcus aureus is a persistent human pathogen responsible for a variety of infections ranging from soft-tissue infections to bacteremia. It produces a variety of virulence factors which are responsible for specific acute staphylococcal toxaemia syndromes. The objective of this study was to determine the prevalence of a repertoire of toxin genes among Malaysian MRSA strains and their genetic diversity by PCR-RFLP of coa gene. One hundred eighty-eight strains (2003, 2004, 2007 and 2008) of methicillin-resistant S. aureus (MRSA) were screened for 20 genes encoding for extracellular virulence determinant (sea, seb, sec, sed, see, seg, seh, sei, sej, tst, eta, etb, etd) and adhesins (cna, etb, fnbA, fnbB, hlg, ica, sdrE). The genetic relatedness of these strains was determined by PCR-RFLP of coa gene and agr grouping. Majority of the strains were tested positive for efb and fnbA (96% each), ica (78%) and hlg (59%) genes. A total of 101 strains were positive for at least one type of staphylococcal enterotoxin genes with sea being the predominant. Genes for seb, sed, see, seh, sej, eta and etb were not detected in any of the MRSA strains. The prevalence of sea, sec and ica among strains isolated in 2008 was increased significantly (p< 0.05) compared to 2003. Most of the strains were of agr type I (97.5%) followed by agr type II (1.2%) and agr type III (0.6%). All sea, sei and tst gene-positive strains were of agr type I. The only etd positive strain was agr type III. PCR-RFLP of coa produced 47 different patterns. The number of strains with virulence factors (sea, sec and ica) had increased over the years. No direct correlation between PCR-RFLP- coa profiles and virulotypes was observed.
    Matched MeSH terms: Bacterial Toxins/genetics*
  2. Lim KT, Hanifah YA, Mohd Yusof MY, Ito T, Thong KL
    J Microbiol Immunol Infect, 2013 Jun;46(3):224-33.
    PMID: 23523045 DOI: 10.1016/j.jmii.2013.02.001
    Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) continue to be a problem for clinicians worldwide. The objective of this study was to determine the changes in antibiograms of MRSA and their genotypic characteristics.
    Matched MeSH terms: Bacterial Toxins/genetics
  3. Ghafourian S, Raftari M, Sadeghifard N, Sekawi Z
    Curr Issues Mol Biol, 2014;16:9-14.
    PMID: 23652423
    The toxin-antitoxin (TA) systems are systems in which an unstable antitoxin inhibits a stable toxin. This review aims to introduce the TA system and its biological application in bacteria. For this purpose, first we introduce a new classification for the TA systems based on how the antitoxin can neutralize the toxin, we then describe the functions of TA systems and finally review the application of these systems in biotechnology.
    Matched MeSH terms: Bacterial Toxins/genetics*
  4. Cheong TG, Chan M, Kurunathan S, Ali SA, ZiNing T, Zainuddin ZF, et al.
    Microb Pathog, 2010 Feb;48(2):85-90.
    PMID: 19900531 DOI: 10.1016/j.micpath.2009.11.001
    Vibrio cholerae is a Gram-negative bacterium that causes diarrheal disease. V. cholerae O1 and O139 serogroups are toxigenic and are known to cause epidemic cholera. These serogroups produce cholera toxin and other accessory toxins such as accessory cholera enterotoxin, zonula occludens toxin, and multifunctional, autoprocessing repeat in toxin (MARTX). In the present study, we incorporated mutated rtxA and rtxC genes that encode MARTX toxin into the existing aminolevulinic acid (ALA) auxotrophic vaccine candidate VCUSM2 of V. cholerae O139 serogroup. The rtxC mutant was named VCUSM9 and the rtxC/rtxA mutant was named VCUSM10. VCUSM9 and VCUSM10 were able to colonize intestinal cells well, compared with the parent vaccine strain, and produced no fluid accumulation in a rabbit ileal loop model. Cell rounding and western blotting assays indicated that mutation of the rtxC gene alone (VCUSM9 strain) did not abolish MARTX toxicity. However mutation of both the rtxA and rtxC genes (VCUSM10) completely abolished MARTX toxicity. Thus we have produced a new, less reactogenic, auxotrophic rtxC/rtxA mutated vaccine candidate against O139 V. cholerae.
    Matched MeSH terms: Bacterial Toxins/genetics*
  5. Anuradha K, Foo HL, Mariana NS, Loh TC, Yusoff K, Hassan MD, et al.
    J Appl Microbiol, 2010 Nov;109(5):1632-42.
    PMID: 20602654 DOI: 10.1111/j.1365-2672.2010.04789.x
    To evaluate a live recombinant Lactococcus lactis vaccine expressing aerolysin genes D1 (Lac-D1ae) and/or D4 (Lac-D4ae) in protection against Aeromonas hydrophila in tilapia (Oreochromis niloticus).
    Matched MeSH terms: Bacterial Toxins/genetics*
  6. Mat Azis N, Pung HP, Abdul Rachman AR, Amin Nordin S, Sarchio SNE, Suhaili Z, et al.
    J Infect Public Health, 2017 Mar-Apr;10(2):156-164.
    PMID: 27033676 DOI: 10.1016/j.jiph.2016.02.013
    The aim of the present study was to assess and compare the antimicrobial susceptibility pattern against a panel of antibiotics and molecular and methicillin resistance-associated genotypes of 120 carriage S. aureus isolates previously isolated from a student population at two isolation events within a one-month interval. The antibiotic susceptibility of isolates was determined using the Kirby-Bauer disc-diffusion method (cefoxitin by Etest). The MRSA was screened using polymerase chain reaction for the presence of the mecA gene. The mecA-positive isolates were subjected to staphylococcal cassette chromosome (SCC) mec typing, multilocus sequence typing (MLST) and eBURST analysis. All isolates were characterized for the presence of the Panton-Valentine leukocidin (PVL) gene, an enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) pattern and the spa type. For the two occasions where S. aureus was isolated, the highest frequency of resistance was observed for penicillin (70% and 65%, respectively), with a lower rate against erythromycin and tetracycline (<12%). All isolates were susceptible to ciprofloxacin and gentamycin. As for methicillin resistance, eight isolates had minimum inhibitory concentrations (MIC) of resistant categories, but 10 isolates (8.33%) were positive for the mecA gene. The mecA-positive isolates belonged to SCCmec types I (n=9) and V (n=1). MLST was resolved for only three MRSAs, ST508 (n=1), ST88 (n=1) and ST96 (n=1). The results of the eBURST analysis showed that the MRSA isolates analyzed in the present study were potentially related to MRSA identified in other countries. Approximately half of the persistent S. aureus carriers harbored S. aureus of a similar spa type in the respective individuals during both isolation events. A persistent antimicrobial pattern and limited distinct MRSAs were observed over the short study period. The latter frequently exhibited SCCmec type I, commonly associated with hospital-acquired (HA) characteristics, but further delineation is needed to justify the origins of these bacteria.
    Matched MeSH terms: Bacterial Toxins/genetics
  7. Riley TV, Collins DA, Karunakaran R, Kahar MA, Adnan A, Hassan SA, et al.
    J Clin Microbiol, 2018 Jun;56(6).
    PMID: 29563206 DOI: 10.1128/JCM.00170-18
    Accumulating evidence shows a high prevalence of Clostridium difficile in Southeast Asia associated with a range of clinical presentations. However, severe infections are rarely reported. We investigated C. difficile infection (CDI) across four hospitals in Kuala Lumpur and Kota Bharu, Malaysia. Enzyme immunoassays for glutamate dehydrogenase (GDH) and toxin A or B were performed on diarrheal stool specimens collected from patients in 2015 and 2016. Specimens were also cultured and isolates of C. difficile characterized by PCR ribotyping and detection of toxin genes. In total, 437 specimens were collected and fecal toxin was detected in 3.0%. A further 16.2% of specimens were GDH positive and toxin negative. After culture, toxigenic strains were isolated from 10.3% and nontoxigenic strains from 12.4% of specimens. The most prevalent PCR ribotypes (RTs) were RT 017 (20.0%) and RT 043 (10.0%). The high prevalence of RT 017 and nontoxigenic strains in Malaysia and in neighboring Thailand and Indonesia suggests that they localize to the region of Southeast Asia, with an implication that they may mediate the burden of CDI in the region.
    Matched MeSH terms: Bacterial Toxins/genetics*
  8. Stegger M, Wirth T, Andersen PS, Skov RL, De Grassi A, Simões PM, et al.
    mBio, 2014 Aug 26;5(5):e01044-14.
    PMID: 25161186 DOI: 10.1128/mBio.01044-14
    Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized in Europe and worldwide in the late 1990s. Within a decade, several genetically and geographically distinct CA-MRSA lineages carrying the small SCCmec type IV and V genetic elements and the Panton-Valentine leukocidin (PVL) emerged around the world. In Europe, the predominant CA-MRSA strain belongs to clonal complex 80 (CC80) and is resistant to kanamycin/amikacin and fusidic acid. CC80 was first reported in 1993 but was relatively rare until the late 1990s. It has since been identified throughout North Africa, the Middle East, and Europe, with recent sporadic reports in sub-Saharan Africa. While strongly associated with skin and soft tissue infections, it is rarely found among asymptomatic carriers. Methicillin-sensitive S. aureus (MSSA) CC80 strains are extremely rare except in sub-Saharan Africa. In the current study, we applied whole-genome sequencing to a global collection of both MSSA and MRSA CC80 isolates. Phylogenetic analyses strongly suggest that the European epidemic CA-MRSA lineage is derived from a PVL-positive MSSA ancestor from sub-Saharan Africa. Moreover, the tree topology suggests a single acquisition of both the SCCmec element and a plasmid encoding the fusidic acid resistance determinant. Four canonical SNPs distinguish the derived CA-MRSA lineage and include a nonsynonymous mutation in accessory gene regulator C (agrC). These changes were associated with a star-like expansion into Europe, the Middle East, and North Africa in the early 1990s, including multiple cases of cross-continent imports likely driven by human migrations.

    IMPORTANCE: With increasing levels of CA-MRSA reported from most parts of the Western world, there is a great interest in understanding the origin and factors associated with the emergence of these epidemic lineages. To trace the origin, evolution, and dissemination pattern of the European CA-MRSA clone (CC80), we sequenced a global collection of strains of the S. aureus CC80 lineage. Our study determined that a single descendant of a PVL-positive methicillin-sensitive ancestor circulating in sub-Saharan Africa rose to become the dominant CA-MRSA clone in Europe, the Middle East, and North Africa. In the transition from a methicillin-susceptible lineage to a successful CA-MRSA clone, it simultaneously became resistant to fusidic acid, a widely used antibiotic for skin and soft tissue infections, thus demonstrating the importance of antibiotic selection in the success of this clone. This finding furthermore highlights the significance of horizontal gene acquisitions and underscores the combined importance of these factors for the success of CA-MRSA.

    Matched MeSH terms: Bacterial Toxins/genetics
  9. Bakar FA, Yeo CC, Harikrishna JA
    BMC Biotechnol, 2015;15:26.
    PMID: 25887501 DOI: 10.1186/s12896-015-0138-8
    Bacterial toxin-antitoxin systems usually comprise of a pair of genes encoding a stable toxin and its cognate labile antitoxin and are located in the chromosome or in plasmids of several bacterial species. Chromosomally-encoded toxin-antitoxin systems are involved in bacterial stress responses and activation of the toxins usually leads to cell death or dormancy. Overexpression of the chromosomally-encoded YoeB toxin from the yefM-yoeB toxin-antitoxin locus of the Gram-positive bacterium Streptococcus pneumoniae has been shown to cause cell death in S. pneumoniae as well as E. coli.
    Matched MeSH terms: Bacterial Toxins/genetics
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