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Search Results: 1 - 6 of 6 matches for " Aunchalee Thanwisai "
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Identification and isolation of insecticidal oxazoles from Pseudomonas spp.
Florian Grundmann,Veronika Dill,Andrea Dowling,Aunchalee Thanwisai
Beilstein Journal of Organic Chemistry , 2012, DOI: 10.3762/bjoc.8.85
Abstract: Two new and five known oxazoles were identified from two different Pseudomonas strains in addition to the known pyrones pseudopyronine A and B. Labeling experiments confirmed their structures and gave initial evidence for a novel biosynthesis pathway of these natural oxazoles. In order to confirm their structure, they were synthesized, which also allowed tests of their bioactivity. Additionally, the bioactivities of the synthesis intermediates were also investigated revealing interesting biological activities for several compounds despite their overall simple structures.
Effect of colony morphology variation of Burkholderia pseudomallei on intracellular survival and resistance to antimicrobial environments in human macrophages in vitro
Sarunporn Tandhavanant, Aunchalee Thanwisai, Direk Limmathurotsakul, Sunee Korbsrisate, Nicholas PJ Day, Sharon J Peacock, Narisara Chantratita
BMC Microbiology , 2010, DOI: 10.1186/1471-2180-10-303
Abstract: Morphotype was associated with survival in the presence of H2O2 and antimicrobial peptide LL-37, but not with susceptibility to acid, acidified sodium nitrite, or resistance to lysozyme, lactoferrin, human neutrophil peptide-1 or human beta defensin-2. Incubation under anaerobic conditions was a strong driver for switching of type III to an alternative morphotype. Differences were noted in the survival and replication of the three types following uptake by human macrophages, but marked strain-to strain-variability was observed. Uptake of type III alone was associated with colony morphology switching.Morphotype is associated with phenotypes that alter the ability of B. pseudomallei to survive in adverse environmental conditions.Burkholderia pseudomallei is an environmental Gram-negative bacterium that causes a severe and often fatal disease called melioidosis. This is an important cause of sepsis in south-east Asia and northern Australia, a geographic distribution that mirrors the presence of B. pseudomallei in the environment [1]. Melioidosis may develop following bacterial inoculation or inhalation and occurs most often in people with regular contact with contaminated soil and water [1]. Clinical manifestations of melioidosis are highly variable and range from fulminant septicemia to mild localized infection. The overall mortality rate is 40% in northeast Thailand (rising to 90% in patients with severe sepsis) and 20% in northern Australia [1,2].A major feature of melioidosis is that bacterial eradication is difficult to achieve. Fever clearance time is often prolonged (median 8 days), antimicrobial therapy is required for 12-20 weeks, and relapse occurs in around 10% of patients despite an appropriate course of antimicrobial therapy [3,4]. The basis for persistence in the infected human host is unknown, although several observations made to date may be relevant to the clinical behaviour of this organism [2,5]. B. pseudomallei can resist the action of bactericidal
Diversity of Xenorhabdus and Photorhabdus spp. and Their Symbiotic Entomopathogenic Nematodes from Thailand
Aunchalee Thanwisai,Sarunporn Tandhavanant,Natnaree Saiprom,Nick R. Waterfield,Phan Ke Long,Helge B. Bode,Sharon J. Peacock,Narisara Chantratita
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043835
Abstract: Xenorhabdus and Photorhabdus spp. are bacterial symbionts of entomopathogenic nematodes (EPNs). In this study, we isolated and characterized Xenorhabdus and Photorhabdus spp. from across Thailand together with their associated nematode symbionts, and characterized their phylogenetic diversity. EPNs were isolated from soil samples using a Galleria-baiting technique. Bacteria from EPNs were cultured and genotyped based on recA sequence. The nematodes were identified based on sequences of 28S rDNA and internal transcribed spacer regions. A total of 795 soil samples were collected from 159 sites in 13 provinces across Thailand. A total of 126 EPNs isolated from samples taken from 10 provinces were positive for Xenorhabdus (n = 69) or Photorhabdus spp. (n = 57). Phylogenetic analysis separated the 69 Xenorhabdus isolates into 4 groups. Groups 1, 2 and 3 consisting of 52, 13 and 1 isolates related to X. stockiae, and group 4 consisting of 3 isolates related to X. miraniensis. The EPN host for isolates related to X. stockiae was S. websteri, and for X. miraniensis was S. khoisanae. The Photorhabdus species were identified as P. luminescens (n = 56) and P. asymbiotica (n = 1). Phylogenenic analysis divided P. luminescens into five groups. Groups 1 and 2 consisted of 45 and 8 isolates defined as subspecies hainanensis and akhurstii, respectively. One isolate was related to hainanensis and akhurstii, two isolates were related to laumondii, and one isolate was the pathogenic species P. asymbiotica subsp. australis. H. indica was the major EPN host for Photorhabdus. This study reveals the genetic diversity of Xenorhabdus and Photorhabdus spp. and describes new associations between EPNs and their bacterial symbionts in Thailand.
Genetic Diversity and Microevolution of Burkholderia pseudomallei in the Environment
Narisara Chantratita equal contributor,Vanaporn Wuthiekanun equal contributor,Direk Limmathurotsakul,Mongkol Vesaratchavest,Aunchalee Thanwisai,Premjit Amornchai,Sarinna Tumapa,Edward J. Feil,Nicholas P. Day,Sharon J. Peacock
PLOS Neglected Tropical Diseases , 2008, DOI: 10.1371/journal.pntd.0000182
Abstract: Background The soil dwelling Gram-negative pathogen Burkholderia pseudomallei is the cause of melioidosis. The diversity and population structure of this organism in the environment is poorly defined. Methods and Findings We undertook a study of B. pseudomallei in soil sampled from 100 equally spaced points within 237.5 m2 of disused land in northeast Thailand. B. pseudomallei was present on direct culture of 77/100 sampling points. Genotyping of 200 primary plate colonies from three independent sampling points was performed using a combination of pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Twelve PFGE types and nine sequence types (STs) were identified, the majority of which were present at only a single sampling point. Two sampling points contained four STs and the third point contained three STs. Although the distance between the three sampling points was low (7.6, 7.9, and 13.3 meters, respectively), only two STs were present in more than one sampling point. Each of the three samples was characterized by the localized expansion of a single B. pseudomallei clone (corresponding to STs 185, 163, and 93). Comparison of PFGE and MLST results demonstrated that two STs contained strains with variable PFGE banding pattern types, indicating geographic structuring even within a single MLST-defined clone. Conclusions We discuss the implications of this extreme structuring of genotype and genotypic frequency in terms of micro-evolutionary dynamics and ecology, and how our results may inform future sampling strategies.
Factors Predicting and Reducing Mortality in Patients with Invasive Staphylococcus aureus Disease in a Developing Country
Emma K. Nickerson, Vanaporn Wuthiekanun, Gumphol Wongsuvan, Direk Limmathurosakul, Pramot Srisamang, Weera Mahavanakul, Janjira Thaipadungpanit, Krupal R. Shah, Arkhom Arayawichanont, Premjit Amornchai, Aunchalee Thanwisai, Nicholas P. Day, Sharon J. Peacock
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0006512
Abstract: Background Invasive Staphylococcus aureus infection is increasingly recognised as an important cause of serious sepsis across the developing world, with mortality rates higher than those in the developed world. The factors determining mortality in developing countries have not been identified. Methods A prospective, observational study of invasive S. aureus disease was conducted at a provincial hospital in northeast Thailand over a 1-year period. All-cause and S. aureus-attributable mortality rates were determined, and the relationship was assessed between death and patient characteristics, clinical presentations, antibiotic therapy and resistance, drainage of pus and carriage of genes encoding Panton-Valentine Leukocidin (PVL). Principal Findings A total of 270 patients with invasive S. aureus infection were recruited. The range of clinical manifestations was broad and comparable to that described in developed countries. All-cause and S. aureus-attributable mortality rates were 26% and 20%, respectively. Early antibiotic therapy and drainage of pus were associated with a survival advantage (both p<0.001) on univariate analysis. Patients infected by a PVL gene-positive isolate (122/248 tested, 49%) had a strong survival advantage compared with patients infected by a PVL gene-negative isolate (all-cause mortality 11% versus 39% respectively, p<0.001). Multiple logistic regression analysis using all variables significant on univariate analysis revealed that age, underlying cardiac disease and respiratory infection were risk factors for all-cause and S. aureus-attributable mortality, while one or more abscesses as the presenting clinical feature and procedures for infectious source control were associated with survival. Conclusions Drainage of pus and timely antibiotic therapy are key to the successful management of S. aureus infection in the developing world. Defining the presence of genes encoding PVL provides no practical bedside information and draws attention away from identifying verified clinical risk factors and those interventions that save lives.
Synthesis, Isolation of Phenazine Derivatives and Their Antimicrobial Activities
Walailak Journal of Science and Technology , 2009, DOI: 10.2004/vol6iss1pp79-91
Abstract: Antimicrobial activity of natural phenazine-1-carboxylic acid (PCA) from Pseudomonas aeruginosa TISTR 781 and synthetic phenazine-5,10-dioxide (PDO), prepared by oxidation of the phenazine, were evaluated by in vitro disc diffusion and minimal inhibitory concentration (MIC) methods. The results indicated that both phenazine derivatives differed clearly in their antimicrobial activity. PCA showed better efficacy against growth of Acidovorax avenae subsp. citrulli, Bacillus subtilis, Candida albicans, Escherichia coli and Xanthomonas campestris pv. vesicatoria than PDO at low concentrations of PCA (MIC; 17.44 - 34.87 ppm) as an antimicrobial agent. In contrast, PDO acted as a stronger inhibitor than PCA when tested against Pseudomonas syringae and Enterobacter aerogenes. The last bacterial strain, Ralstonia solanacearum, can be suppressed by the same concentration of PCA and PDO (MIC; 62.50 ppm). The data provided beneficial information for choosing phenazine types to inhibit some general strains and plant pathogenic bacteria.
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