Browsing by Author "Putthapoom Lumjiaktase"

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    Development of Multiplex PCR for detection of methicillin resistance and MLSB resistance genes in Staphylococcus aureus
    (Mahidol University. Mahidol University Library and Knowledge Center, 2015) Netiluk Tantavutt; Pitak Santanirand; Putthapoom Lumjiaktase
    Nosocomial infection caused by multidrug resistant staphylococci such as methicillin or macrolide-lincosamide-streptogramins B (MLSB) resistance is a growing problem for many health care institutions. Of all species of staphylococci, Staphylococcus aureus (S. aureus) has the greatest pathogenic potential. Methicillin-resistant Staphylococcus aureus (MRSA) infections are associated with increased morbidity and mortality. Rapid identification of the organism as well as drug resistance is crucial for infected patients. Therefore, in this study, a new multiplex PCR for identification of S. aureus and detection of certain antimicrobial resistant genes was developed, in order to improve the speed of detection from suspected bacterial colonies. New specific primers of five target genes, femA (for S. aureus identification), mecA (for oxacillin or methicillin resistance), ermA, B and C (for MLSB resistance) were designed and tested against 250 clinical isolates of Staphylococcus spp. comparing with the conventional identification and susceptibility test in routine process. All five primers revealed 100% specificity to their target genes and the results showed 100% concordance with the phenotypic testings. All methicillin resistant isolates contained the mecA gene. The prevalence of the ermA, ermB and ermC genes in erythromycin resistant S aureus were 53.4%, 1.1% and 12.6% respectively while prevalence of the ermA, ermB, and ermC in coagulase negative staphylococci (CoNS) were 6.6%, 1.3%, and 46.1% respectively . In contrast to S. aureus, the ermC was found to be predominated among erythromycin resistant CoNS isolates. With this specific multiplex PCR, the identification of S. aureus and CoNS as well as two groups of most important resistant genes could be performed rapidly and reduced approximately 24 hr of turnaround time comparing to the routine process.
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    Efficient short-term expansion of human peripheral blood regulatory T cells for co-culture suppression assay
    (2019-11-02) Korawit Kanjana; Karan Paisooksantivatana; Ponpan Matangkasombut; Parawee Chevaisrakul; Putthapoom Lumjiaktase; Faculty of Medicine, Ramathibodi Hospital, Mahidol University; Mahidol University
    © 2019, © 2019 The Author(s). Published with license by Taylor & Francis Group, LLC. Regulatory T cells (Tregs) are a small population of CD4+ lymphocytes and play a key role as suppressors of the immune system, a role that can be identified by employing a co-culture suppression assay. Conventional protocol requires a long period of in vitro expansion of Treg numbers; hence, this study describes an establishment of a co-culture suppression assay using a short-term expansion of peripheral blood (PB) Tregs and autologous T cells (Tconvs) IL-2-pre-cultured in parallel for the same length of time, thereby obviating the need of freeze/thawed autologous Tconvs. Tregs and Tconvs were isolated from PB mononuclear cells employing magnetic bead-aided depletion of CD8+ cells followed by cell sorting of CD4+ CD25high+CD127low- (Treg) and CD4+ CD25-CD127+ (Tconv) cell populations. Following a 3-day co-cultivation period under optimized conditions, Treg suppression activity was monitored by comparing using flow cytometry the number of carboxyfluorescein succinimidyl ester-labeled Tconvs to that of Treg-minus control. The assay allowed significant differentiation between Treg suppression activity of patients with active rheumatoid arthritis and those in remission. This method should be more convenient and time-saving than the conventional Treg suppression assay in current use.
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    Functional Genetic Analysis Reveals a 2-Alkyl-4-Quinolone Signaling System in the Human Pathogen Burkholderia pseudomallei and Related Bacteria
    (2006-07-01) Stephen P. Diggle; Putthapoom Lumjiaktase; Francesca Dipilato; Klaus Winzer; Mongkol Kunakorn; David A. Barrett; Siri Ram Chhabra; Miguel Cámara; Paul Williams; University of Nottingham; Mahidol University
    Pseudomonas aeruginosa synthesizes diverse 2-alkyl-4(1H)-quinolones (AHQs), including the signaling molecule 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), via the pqsABCDE locus. By examining the genome databases, homologs of the pqs genes were identified in other bacteria. However, apart from P. aeruginosa, only Burkholderia pseudomallei and B. thailandensis contained a complete pqsA-E operon (termed hhqA-E). By introducing the B. pseudomallei hhqA and hhqE genes into P. aeruginosa pqsA and pqsE mutants, we show that they are functionally conserved and restore virulence factor and PQS production. B. pseudomallei, B. thailandensis, B. cenocepacia, and P. putida each produced 2-heptyl-4(1H)-quinolone (HHQ), but not PQS. Mutation of hhqA in B. pseudomallei resulted in the loss of AHQ production, altered colony morphology, and enhanced elastase production, which was reduced to parental levels by exogenous HHQ. These data reveal a role for AHQs in bacterial cell-to-cell communication beyond that seen in P. aeruginosa. © 2006 Elsevier Ltd. All rights reserved.
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    Identification and characterization of quorum sensing and quinolone sensing systems in Burkholderia pseudomallei
    (Mahidol University. Mahidol University Library and Knowledge Center, 2023) Putthapoom Lumjiaktase; Mongkol Kunakorn
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    Identification of the quorum sensing genes in Burkholderia Pseudomallei
    (Mahidol University. Mahidol University Library and Knowledge Center, 2002) Putthapoom Lumjiaktase; Mongkol Kunakorn; Sumalee Tungpradabkul
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    Regulatory T Cell Suppressive Activity Predicts Disease Relapse During Disease-Modifying Anti-rheumatic Drug Dose Reduction in Rheumatoid Arthritis: A Prospective Cohort Study
    (2020-02-04) Korawit Kanjana; Parawee Chevaisrakul; Ponpan Matangkasombut; Karan Paisooksantivatana; Putthapoom Lumjiaktase; Faculty of Medicine, Ramathibodi Hospital, Mahidol University; Mahidol University; Harvard Medical School
    © Copyright © 2020 Kanjana, Chevaisrakul, Matangkasombut, Paisooksantivatana and Lumjiaktase. When the dose of conventional disease-modifying anti-rheumatic drugs (cDMARDs) is tapered in rheumatoid arthritis (RA) patients who achieve sustained remission, biomarkers for predicting disease relapse may be needed. A prospective, unblinded cohort study was conducted in nine RA patients with remission. Peripheral blood samples were collected at baseline and at 6, 12, and 24 weeks after cDMARD dose reduction (dose of combination regimens reduced to 50%) to determine the number of regulatory Foxp3+T cells (Tregs) and other T cell subpopulations as well as Treg suppressive activity. Additionally, plasma levels of 14 cytokines at each time-point were measured via flow cytometry. Univariate and multivariate analyses were performed to identify the factor(s) associated with RA relapse during the observational period. In univariate analysis, Treg suppression and DAS28 and VAS scores were associated with RA relapse after cDMARD dose tapering. However, in multivariate analysis, only Treg suppressive activity (<42%) was found to be an independent factor associated with RA relapse after cDMARD dose reduction to 50%. Of all patients who had ≥42% Treg suppressive activity during cDMAD reduction, three-fourth patients remained in the remission stage for 24 weeks. Treg suppressive activity (<42%) in RA patients with remission could be a potential biomarker for predicting RA relapse after cDMARD dose reduction, especially over a short-term period (24 weeks).