Wijit Wonglumsom | Mahidol University (original) (raw)

Papers by Wijit Wonglumsom

Food Science and Biotechnology, 2016

เวชสารแพทย์ทหารบก, 2012

It is recognized that clinical laboratory service plays an important role in patient care managem... more It is recognized that clinical laboratory service plays an important role in patient care management and clinical laboratory service differs from other medical service. The unique role of clinical laboratory is producing the quality test results of individual patient. Therefore, to achieve the quality test result, one must understand the whole process of clinical laboratory testing. Clinical laboratory process is composed of two main phases; the non-analytical phase and analytical phase. The non-analytical phase is subdivided into pre-analytical and post-analytical phases. Nowadays, the analytical phase of clinical laboratory testing is very well controlled. Since it is the most concerned of medical technologist

Microcantilever chip fabricated by Micro-Electro-Mechanical System (MEMS) technology was proved t... more Microcantilever chip fabricated by Micro-Electro-Mechanical System (MEMS) technology was proved to develop as a biosensor device. This chip contains four microfabricated beams of cantilever with gold-coated surface and embedding polysilicon wire. Polysilcon wire acts as a piezoresistor which resistance change indicates microcantilever deflection. Relationship between original resistance and microcantilever deflection shows the detection range of this device within 0-1.1 kΩ. The examination of microcantilever response to avidin immobilization demonstrated that resistance change inducing by avidin absorption could be detected and reaches to level of amount independence at avidin concentration higher 80 µg/ml. The results indicated the possibility to develop this device as a piezoresistive-based biosensor.

Study on extraction of membrane fragments from Escherichia coli and Psuedomonas aeruginosa were d... more Study on extraction of membrane fragments from Escherichia coli and Psuedomonas aeruginosa were determined for using to support Campylobacter cultivation under normal atmosphere. Crude membrane fragments were extracted from 45 strains of E. coli and 44 strains of P. aeruginosa. Strains that provided highest efficiency of oxygen reduction were selected to purify membrane fragments by French pressure cell and ultracentrifugation. The purified membrane fragments were characterized and investigated for supporting Campylobacter jejuni growth in Mueller-Hinton broth. The broth supplemented with and without membrane fragments was incubated under normal atmosphere at 37°C or 42°C. Campylobacter growth in the broth containing purified membrane fragments was initially observed within 6 to 12 hours of incubation while the media without supplemented with membrane fragments showed no growth of the bacteria. Therefore, oxygen reducing membrane fragments prepared from the selected strains could su...

Journal of the Medical Association of Thailand = Chotmaihet thangphaet, 2010

To become a quality clinical laboratory, personnel development is the most important factor. In o... more To become a quality clinical laboratory, personnel development is the most important factor. In order to achieve this goal, it should emphasize that clinical laboratory is not only a testing laboratory; it must be a knowledge-based service laboratory. A smart model for clinical laboratory personnel development under the Human Asset Development (HAD) program had been launched since 2003. To strengthen the competency of clinical laboratory personnel, an appropriate model was developed and apply to the clinical laboratory personnel. Medical technologist who currently worked in clinical laboratory participated in this study. The proposed model consisted of 3 phases. 1) The knowledge providing via update and refresher courses. 2) Application of learned knowledge to practice under close supervision. 3) Training on special topic and self oriented research activity. The outcome of 5 years project was evaluated. After the first phase, they were able to identify and solve their own troublesom...

The Southeast Asian journal of tropical medicine and public health, 2007

Escherichia coli was used to investigate quinolone resistance and mutations in gyrA gene of E. co... more Escherichia coli was used to investigate quinolone resistance and mutations in gyrA gene of E. coli isolated from pet (dog and cat), human (pet's owner), vegetable and edible ice in Bangkok and vicinity. Susceptibility test for nalidixic acid (NA) showed similar percent resistance among the sample sources but a lower ciprofloxacin (CIP) resistance was found particularly in human source. Mutations within quinolone resistance determining region of gyrA gene analyzed using non-radioactive single-strand conformation polymorphism (SSCP) and sequencing showed 10 different SSCP patterns. E. coli isolates from pet, vegetable and ice showed more variety of patterns than strains isolated from human. Four out of 10 SSCP patterns were identified as having mutations in amino acids positions 83 (Ser to Leu) and position 87 (Asp to Asn). These mutations were observed only in NA-resistant strains and combined mutations were observed only in E. coli isolated from humans and pets. As only 24% of ...

The Southeast Asian journal of tropical medicine and public health, 2007

A retrospective study of the patterns of antimicrobial susceptibility and phage types of 111 Salm... more A retrospective study of the patterns of antimicrobial susceptibility and phage types of 111 Salmonella typhi strains isolated in 1996 from Vietnam was carried out. The strains were tested for susceptibility to chloramphenicol, ampicillin, tetracycline, trimethoprim-sulfamethoxazole, nalidixic acid, ceftazidime, ceftriaxone and ciprofloxacin. Simultaneous resistance to chloramphenicol, ampicillin, tetracycline and trimethoprim-sulfamethoxazole were present in 84 strains (75.7%). Nalidixic acid resistance was only observed in 2 multidrug-resistant strains (1.8%). Twenty-one strains (18.9%) were completely susceptible to all drugs tested. All 111 strains were susceptible to ceftazidime, ceftriaxone and cipropfloxacin. The MIC values for chloramphenicol, ampicillin and trimethoprim-sulfamethoxazole corresponded with the results by disk diffusion method. On Vi phage-typing, 5 different phage types (28, A, D1, E1 and M1) were found in 12 strains (10.8%). However, most S. typhi strains we...

Biosensors and Bioelectronics, 2015

Cite this article as: Numfon Khemthongcharoen, Wijit Wonglumsom, Assawapong Suppat, Kata Jaruwong... more Cite this article as: Numfon Khemthongcharoen, Wijit Wonglumsom, Assawapong Suppat, Kata Jaruwongrungsee, Adisorn Tuantranont and Chamras Promptmas, Piezoresistive microcantilever-based DNA sensor for sensitive detection of pathogenic Vibrio cholera O1 in food sample, Biosensors and Bioelectronic, http://dx.

PLoS ONE, 2011

The ethanolic extract from Rhodomyrtus tomentosa leaf exhibited good antibacterial activities aga... more The ethanolic extract from Rhodomyrtus tomentosa leaf exhibited good antibacterial activities against both methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus ATCC 29213. Its minimal inhibitory concentration (MIC) values ranged from 31.25-62.5 µg/ml, and the minimal bactericidal concentration (MBC) was 250 µg/ml. Rhodomyrtone, an acylphloroglucinol derivative, was 62.5-125 times more potent at inhibiting the bacteria than the ethanolic extract, the MIC and MBC values were 0.5 µg/ml and 2 µg/ml, respectively. To provide insights into antibacterial mechanisms involved, the effects of rhodomyrtone on cellular protein expression of MRSA have been investigated using proteomic approaches. Proteome analyses revealed that rhodomyrtone at subinhibitory concentration (0.174 µg/ml) affected the expression of several major functional classes of whole cell proteins in MRSA. The identified proteins involve in cell wall biosynthesis and cell division, protein degradation, stress response and oxidative stress, cell surface antigen and virulence factor, and various metabolic pathways such as amino acid, carbohydrate, energy, lipid, and nucleotide metabolism. Transmission electron micrographs confirmed the effects of rhodomyrtone on morphological and ultrastructural alterations in the treated bacterial cells. Biological processes in cell wall biosynthesis and cell division were interrupted. Prominent changes including alterations in cell wall, abnormal septum formation, cellular disintegration, and cell lysis were observed. Unusual size and shape of staphylococcal cells were obviously noted in the treated MRSA. These pioneer findings on proteomic profiling and phenotypic features of rhodomyrtone-treated MRSA may resolve its antimicrobial mechanisms which could lead to the development of a new effective regimen for the treatment of MRSA infections.

Journal of Rapid Methods & Automation in Microbiology, 2009

... in enterococci isolated from fish ponds, which use the manure from animal husbandry as fertil... more ... in enterococci isolated from fish ponds, which use the manure from animal husbandry as fertilizers (Petersen and Dalsgaard 2003). ... tetA conferring resistance to tetracycline by efflux (Chopra and Roberts 2001), cat1 encoding chloramphenicol resistance gene (Maynard et al. ...

Journal of Rapid Methods and Automation in Microbiology, 2001

with Oxyrase @ , sheep blood, hemin or yeast extract for recovery of Campylobacter was evaluated.... more with Oxyrase @ , sheep blood, hemin or yeast extract for recovery of Campylobacter was evaluated. Five strains of C. jejuni and one strain of C. coli were cultured in HB with or without Oxyrase ? NFB with or without Oxyrase @ , NFB without hemin, and NFB plus yeast extract without hemin. The HB without Oxyrase@ was evacuated and flushed three times with mixed gas (5% O,, 10% CO,, and 85% NJ prior to incubation. The effect of blood in HB supplemented with Oxyrase @ on the growth of Campylobacter was also examined. Hunt broth showed significantly better performance than NFB @ < 0.05). Supplementation of 0.2% hemin and 0.6% yeast extract stimulated growth by up to 2 log CFU/mL. depending on strains. Addition of 7% lysed blood enhanced growth of C. jejuni, and differences were significant at 6 h and 24 h of incubation. At 20 h of incubation, broth containing 0.6 units/ml of Oxyrase@ yielded Campylobacter counts of 8.6 to 10.9 log CFU/mL, and the broth flushed with mixed gas provided counts of 9.4 to 11.0 log CFU/mL. No statistical difference 0, > 0.05) was found between the Oxyrase @method and gas replacement method at incubation times of 12 h, 20 h, 28 h, and 36 h for all strains tested. Dissolved oxygen levels of all enrichment media were less than I . 5 rng/L. Using Oxyrase @supplemented HB without the cumbersome gassing step provides a simple and time-saving procedure for culturing Campylobacter jejuni and C. coli.

Journal of Rapid Methods & Automation in Microbiology, 2009

ABSTRACT ABSTRACTA multiplex polymerase chain reaction (PCR) assay has been developed for the ide... more ABSTRACT ABSTRACTA multiplex polymerase chain reaction (PCR) assay has been developed for the identification of the four thermophilic Campylobacter commonly associated with human gastroenteritis including C. jejuni, C. coli, C. lari and C. upsaliensis. The best combination of primers and the annealing temperature of multiplex PCR were examined. Detection limit was 2 × 105 cfu and 100 ng of DNA or whole-cell suspension. The multiplex PCR was applied for the direct detection and differentiation of Campylobacter species in 33 human and 45 chicken caeca isolates. Of the 78 specimens evaluated by the multiplex PCR, 55 (70.5%) were identified as C. jejuni, 18 (23.0%) as C. coli and 5 (6.41%) as a mixed infection with both species. Comparison of hippurate test and multiplex PCR demonstrated five (6.41%) isolates with false-positive hippurate enzymic activity and three (3.85%) with false-negative activity. cdtB gene was detected in 100% and 38.9% of C. jejuni and C. coli, respectively. This multiplex PCR was found to be rapid, easy to perform and had a high sensitivity and specificity, even with mixed cultures. The system is useful for the detection of the presence of cdtB gene that is responsible for toxin activity in Campylobacter.PRACTICAL APPLICATIONSOur multiplex polymerase chain reaction (PCR) allows in a single tube PCR, the identification of the four clinically important Campylobacter species, with a simultaneous detection of the cdtB gene. The PCR works well in our hands with both purified genomic DNA and whole-cell suspension. This should greatly speed up identification by replacing the current biochemical phenotypic schemes. In addition, the system can detect the presence of cdtB gene that encodes the cytolethal-distending toxin activity.

Journal of Microbiological Methods, 2009

Conventional procedures for isolation of thermophilic Campylobacter spp. from chicken are complex... more Conventional procedures for isolation of thermophilic Campylobacter spp. from chicken are complex, labor intensive, and time-consuming. The objective of this study was to create a novel Campylobacter culturing apparatus. A main concept of the device was based on the ability of Campylobacter to pass through a 0.45 μm pore size filter in viscous media. Preliminary study demonstrated that only viable Campylobacter moved through the membrane filter and could multiply in the enrichment culture. C. jejuni, C. coli, C. lari, and C. upsaliensis in the chicken samples were detected at cell concentrations as low as 10 cfu/g, after 24 h incubation at 42°C. In total, 84 retail chicken samples were comparatively studied using both conventional method and apparatus. Sixteen samples (19.05%) were positive by the apparatus method; 14 (16.66%) of these positive samples contained C. coli and 2 (2.38%) contained C. jejuni. With the conventional method, 7 (8.33%) samples were positive 7 (8.33%) with C. coli. In conclusion, the apparatus detected more positive samples than did the conventional culture method.

Journal of Microbiological Methods, 2010

The effects of chemotactic stimuli on motility ability of viable Campylobacter to pass through a ... more The effects of chemotactic stimuli on motility ability of viable Campylobacter to pass through a 0.45 microm pore size filter in viscous condition were investigated. Reference strains including C. jejuni ATCC 33291, C. coli MUMT 18407, C. lari ATCC 43675, and C. upsaliensis DMST 19055 were used. The initial numbers of artificially-inoculated viable cells per g of chicken meat were approximately 10 to 10(4). Constituents of mucin plus bile (1:1), varieties of amino acids, and sodium salts were added into a soft-agar-coated membrane filter and incubated at both 37 degrees C and 42 degrees C for 24h. The drop plate method was used to determine numbers of viable Campylobacter at 6, 12, 18, and 24h. After 6h, constituents of mucin plus bile at the concentrations of 1, 5, and 10% demonstrated significant increases in numbers of viable cells (p&amp;amp;amp;amp;lt;0.05). The numbers of the organisms at 42 degrees C were higher than those at 37 degrees C. In contrast, no significant difference in cell numbers was observed by adding amino acids or sodium salts. In addition, the role of starvation on chemotactic responses was also studied. Starved cells showed lower chemotactic response than non-starved cells. This method permitted rapid detection of viable thermophilic Campylobacter.

Piezoresistive microcantilever-based DNA chip has been developed for cholera toxin gene detection... more Piezoresistive microcantilever-based DNA chip has been developed for cholera toxin gene detection. This sensor consisted of gold-coated rectangular microcantilever embedding with polysilicon wire as a piezoresistive material. The immobilized ssDNA probe on microcantilever surface worked as a sensing device for cholera toxin gene. The product from polymerase chain reaction (PCR) with designed primer hybridized specifically to ssDNA probe on microcantilever. The interaction between those reaction partners induced structural stress on microcantilever beam and then caused the alteration of its resistance. The DNA sensor chip was examined with PCR product from V. cholerae. The result demonstrated that the resistance of microcantilever increased from 1.3 Ω to 4.9 Ω after the hybridization of PCR product to specific probe.

Food Science and Biotechnology, 2016

เวชสารแพทย์ทหารบก, 2012

It is recognized that clinical laboratory service plays an important role in patient care managem... more It is recognized that clinical laboratory service plays an important role in patient care management and clinical laboratory service differs from other medical service. The unique role of clinical laboratory is producing the quality test results of individual patient. Therefore, to achieve the quality test result, one must understand the whole process of clinical laboratory testing. Clinical laboratory process is composed of two main phases; the non-analytical phase and analytical phase. The non-analytical phase is subdivided into pre-analytical and post-analytical phases. Nowadays, the analytical phase of clinical laboratory testing is very well controlled. Since it is the most concerned of medical technologist

Microcantilever chip fabricated by Micro-Electro-Mechanical System (MEMS) technology was proved t... more Microcantilever chip fabricated by Micro-Electro-Mechanical System (MEMS) technology was proved to develop as a biosensor device. This chip contains four microfabricated beams of cantilever with gold-coated surface and embedding polysilicon wire. Polysilcon wire acts as a piezoresistor which resistance change indicates microcantilever deflection. Relationship between original resistance and microcantilever deflection shows the detection range of this device within 0-1.1 kΩ. The examination of microcantilever response to avidin immobilization demonstrated that resistance change inducing by avidin absorption could be detected and reaches to level of amount independence at avidin concentration higher 80 µg/ml. The results indicated the possibility to develop this device as a piezoresistive-based biosensor.

Study on extraction of membrane fragments from Escherichia coli and Psuedomonas aeruginosa were d... more Study on extraction of membrane fragments from Escherichia coli and Psuedomonas aeruginosa were determined for using to support Campylobacter cultivation under normal atmosphere. Crude membrane fragments were extracted from 45 strains of E. coli and 44 strains of P. aeruginosa. Strains that provided highest efficiency of oxygen reduction were selected to purify membrane fragments by French pressure cell and ultracentrifugation. The purified membrane fragments were characterized and investigated for supporting Campylobacter jejuni growth in Mueller-Hinton broth. The broth supplemented with and without membrane fragments was incubated under normal atmosphere at 37°C or 42°C. Campylobacter growth in the broth containing purified membrane fragments was initially observed within 6 to 12 hours of incubation while the media without supplemented with membrane fragments showed no growth of the bacteria. Therefore, oxygen reducing membrane fragments prepared from the selected strains could su...

Journal of the Medical Association of Thailand = Chotmaihet thangphaet, 2010

To become a quality clinical laboratory, personnel development is the most important factor. In o... more To become a quality clinical laboratory, personnel development is the most important factor. In order to achieve this goal, it should emphasize that clinical laboratory is not only a testing laboratory; it must be a knowledge-based service laboratory. A smart model for clinical laboratory personnel development under the Human Asset Development (HAD) program had been launched since 2003. To strengthen the competency of clinical laboratory personnel, an appropriate model was developed and apply to the clinical laboratory personnel. Medical technologist who currently worked in clinical laboratory participated in this study. The proposed model consisted of 3 phases. 1) The knowledge providing via update and refresher courses. 2) Application of learned knowledge to practice under close supervision. 3) Training on special topic and self oriented research activity. The outcome of 5 years project was evaluated. After the first phase, they were able to identify and solve their own troublesom...

The Southeast Asian journal of tropical medicine and public health, 2007

Escherichia coli was used to investigate quinolone resistance and mutations in gyrA gene of E. co... more Escherichia coli was used to investigate quinolone resistance and mutations in gyrA gene of E. coli isolated from pet (dog and cat), human (pet's owner), vegetable and edible ice in Bangkok and vicinity. Susceptibility test for nalidixic acid (NA) showed similar percent resistance among the sample sources but a lower ciprofloxacin (CIP) resistance was found particularly in human source. Mutations within quinolone resistance determining region of gyrA gene analyzed using non-radioactive single-strand conformation polymorphism (SSCP) and sequencing showed 10 different SSCP patterns. E. coli isolates from pet, vegetable and ice showed more variety of patterns than strains isolated from human. Four out of 10 SSCP patterns were identified as having mutations in amino acids positions 83 (Ser to Leu) and position 87 (Asp to Asn). These mutations were observed only in NA-resistant strains and combined mutations were observed only in E. coli isolated from humans and pets. As only 24% of ...

The Southeast Asian journal of tropical medicine and public health, 2007

A retrospective study of the patterns of antimicrobial susceptibility and phage types of 111 Salm... more A retrospective study of the patterns of antimicrobial susceptibility and phage types of 111 Salmonella typhi strains isolated in 1996 from Vietnam was carried out. The strains were tested for susceptibility to chloramphenicol, ampicillin, tetracycline, trimethoprim-sulfamethoxazole, nalidixic acid, ceftazidime, ceftriaxone and ciprofloxacin. Simultaneous resistance to chloramphenicol, ampicillin, tetracycline and trimethoprim-sulfamethoxazole were present in 84 strains (75.7%). Nalidixic acid resistance was only observed in 2 multidrug-resistant strains (1.8%). Twenty-one strains (18.9%) were completely susceptible to all drugs tested. All 111 strains were susceptible to ceftazidime, ceftriaxone and cipropfloxacin. The MIC values for chloramphenicol, ampicillin and trimethoprim-sulfamethoxazole corresponded with the results by disk diffusion method. On Vi phage-typing, 5 different phage types (28, A, D1, E1 and M1) were found in 12 strains (10.8%). However, most S. typhi strains we...

Biosensors and Bioelectronics, 2015

Cite this article as: Numfon Khemthongcharoen, Wijit Wonglumsom, Assawapong Suppat, Kata Jaruwong... more Cite this article as: Numfon Khemthongcharoen, Wijit Wonglumsom, Assawapong Suppat, Kata Jaruwongrungsee, Adisorn Tuantranont and Chamras Promptmas, Piezoresistive microcantilever-based DNA sensor for sensitive detection of pathogenic Vibrio cholera O1 in food sample, Biosensors and Bioelectronic, http://dx.

PLoS ONE, 2011

The ethanolic extract from Rhodomyrtus tomentosa leaf exhibited good antibacterial activities aga... more The ethanolic extract from Rhodomyrtus tomentosa leaf exhibited good antibacterial activities against both methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus ATCC 29213. Its minimal inhibitory concentration (MIC) values ranged from 31.25-62.5 µg/ml, and the minimal bactericidal concentration (MBC) was 250 µg/ml. Rhodomyrtone, an acylphloroglucinol derivative, was 62.5-125 times more potent at inhibiting the bacteria than the ethanolic extract, the MIC and MBC values were 0.5 µg/ml and 2 µg/ml, respectively. To provide insights into antibacterial mechanisms involved, the effects of rhodomyrtone on cellular protein expression of MRSA have been investigated using proteomic approaches. Proteome analyses revealed that rhodomyrtone at subinhibitory concentration (0.174 µg/ml) affected the expression of several major functional classes of whole cell proteins in MRSA. The identified proteins involve in cell wall biosynthesis and cell division, protein degradation, stress response and oxidative stress, cell surface antigen and virulence factor, and various metabolic pathways such as amino acid, carbohydrate, energy, lipid, and nucleotide metabolism. Transmission electron micrographs confirmed the effects of rhodomyrtone on morphological and ultrastructural alterations in the treated bacterial cells. Biological processes in cell wall biosynthesis and cell division were interrupted. Prominent changes including alterations in cell wall, abnormal septum formation, cellular disintegration, and cell lysis were observed. Unusual size and shape of staphylococcal cells were obviously noted in the treated MRSA. These pioneer findings on proteomic profiling and phenotypic features of rhodomyrtone-treated MRSA may resolve its antimicrobial mechanisms which could lead to the development of a new effective regimen for the treatment of MRSA infections.

Journal of Rapid Methods & Automation in Microbiology, 2009

... in enterococci isolated from fish ponds, which use the manure from animal husbandry as fertil... more ... in enterococci isolated from fish ponds, which use the manure from animal husbandry as fertilizers (Petersen and Dalsgaard 2003). ... tetA conferring resistance to tetracycline by efflux (Chopra and Roberts 2001), cat1 encoding chloramphenicol resistance gene (Maynard et al. ...

Journal of Rapid Methods and Automation in Microbiology, 2001

with Oxyrase @ , sheep blood, hemin or yeast extract for recovery of Campylobacter was evaluated.... more with Oxyrase @ , sheep blood, hemin or yeast extract for recovery of Campylobacter was evaluated. Five strains of C. jejuni and one strain of C. coli were cultured in HB with or without Oxyrase ? NFB with or without Oxyrase @ , NFB without hemin, and NFB plus yeast extract without hemin. The HB without Oxyrase@ was evacuated and flushed three times with mixed gas (5% O,, 10% CO,, and 85% NJ prior to incubation. The effect of blood in HB supplemented with Oxyrase @ on the growth of Campylobacter was also examined. Hunt broth showed significantly better performance than NFB @ < 0.05). Supplementation of 0.2% hemin and 0.6% yeast extract stimulated growth by up to 2 log CFU/mL. depending on strains. Addition of 7% lysed blood enhanced growth of C. jejuni, and differences were significant at 6 h and 24 h of incubation. At 20 h of incubation, broth containing 0.6 units/ml of Oxyrase@ yielded Campylobacter counts of 8.6 to 10.9 log CFU/mL, and the broth flushed with mixed gas provided counts of 9.4 to 11.0 log CFU/mL. No statistical difference 0, > 0.05) was found between the Oxyrase @method and gas replacement method at incubation times of 12 h, 20 h, 28 h, and 36 h for all strains tested. Dissolved oxygen levels of all enrichment media were less than I . 5 rng/L. Using Oxyrase @supplemented HB without the cumbersome gassing step provides a simple and time-saving procedure for culturing Campylobacter jejuni and C. coli.

Journal of Rapid Methods & Automation in Microbiology, 2009

ABSTRACT ABSTRACTA multiplex polymerase chain reaction (PCR) assay has been developed for the ide... more ABSTRACT ABSTRACTA multiplex polymerase chain reaction (PCR) assay has been developed for the identification of the four thermophilic Campylobacter commonly associated with human gastroenteritis including C. jejuni, C. coli, C. lari and C. upsaliensis. The best combination of primers and the annealing temperature of multiplex PCR were examined. Detection limit was 2 × 105 cfu and 100 ng of DNA or whole-cell suspension. The multiplex PCR was applied for the direct detection and differentiation of Campylobacter species in 33 human and 45 chicken caeca isolates. Of the 78 specimens evaluated by the multiplex PCR, 55 (70.5%) were identified as C. jejuni, 18 (23.0%) as C. coli and 5 (6.41%) as a mixed infection with both species. Comparison of hippurate test and multiplex PCR demonstrated five (6.41%) isolates with false-positive hippurate enzymic activity and three (3.85%) with false-negative activity. cdtB gene was detected in 100% and 38.9% of C. jejuni and C. coli, respectively. This multiplex PCR was found to be rapid, easy to perform and had a high sensitivity and specificity, even with mixed cultures. The system is useful for the detection of the presence of cdtB gene that is responsible for toxin activity in Campylobacter.PRACTICAL APPLICATIONSOur multiplex polymerase chain reaction (PCR) allows in a single tube PCR, the identification of the four clinically important Campylobacter species, with a simultaneous detection of the cdtB gene. The PCR works well in our hands with both purified genomic DNA and whole-cell suspension. This should greatly speed up identification by replacing the current biochemical phenotypic schemes. In addition, the system can detect the presence of cdtB gene that encodes the cytolethal-distending toxin activity.

Journal of Microbiological Methods, 2009

Conventional procedures for isolation of thermophilic Campylobacter spp. from chicken are complex... more Conventional procedures for isolation of thermophilic Campylobacter spp. from chicken are complex, labor intensive, and time-consuming. The objective of this study was to create a novel Campylobacter culturing apparatus. A main concept of the device was based on the ability of Campylobacter to pass through a 0.45 μm pore size filter in viscous media. Preliminary study demonstrated that only viable Campylobacter moved through the membrane filter and could multiply in the enrichment culture. C. jejuni, C. coli, C. lari, and C. upsaliensis in the chicken samples were detected at cell concentrations as low as 10 cfu/g, after 24 h incubation at 42°C. In total, 84 retail chicken samples were comparatively studied using both conventional method and apparatus. Sixteen samples (19.05%) were positive by the apparatus method; 14 (16.66%) of these positive samples contained C. coli and 2 (2.38%) contained C. jejuni. With the conventional method, 7 (8.33%) samples were positive 7 (8.33%) with C. coli. In conclusion, the apparatus detected more positive samples than did the conventional culture method.

Journal of Microbiological Methods, 2010

The effects of chemotactic stimuli on motility ability of viable Campylobacter to pass through a ... more The effects of chemotactic stimuli on motility ability of viable Campylobacter to pass through a 0.45 microm pore size filter in viscous condition were investigated. Reference strains including C. jejuni ATCC 33291, C. coli MUMT 18407, C. lari ATCC 43675, and C. upsaliensis DMST 19055 were used. The initial numbers of artificially-inoculated viable cells per g of chicken meat were approximately 10 to 10(4). Constituents of mucin plus bile (1:1), varieties of amino acids, and sodium salts were added into a soft-agar-coated membrane filter and incubated at both 37 degrees C and 42 degrees C for 24h. The drop plate method was used to determine numbers of viable Campylobacter at 6, 12, 18, and 24h. After 6h, constituents of mucin plus bile at the concentrations of 1, 5, and 10% demonstrated significant increases in numbers of viable cells (p&amp;amp;amp;amp;lt;0.05). The numbers of the organisms at 42 degrees C were higher than those at 37 degrees C. In contrast, no significant difference in cell numbers was observed by adding amino acids or sodium salts. In addition, the role of starvation on chemotactic responses was also studied. Starved cells showed lower chemotactic response than non-starved cells. This method permitted rapid detection of viable thermophilic Campylobacter.

Piezoresistive microcantilever-based DNA chip has been developed for cholera toxin gene detection... more Piezoresistive microcantilever-based DNA chip has been developed for cholera toxin gene detection. This sensor consisted of gold-coated rectangular microcantilever embedding with polysilicon wire as a piezoresistive material. The immobilized ssDNA probe on microcantilever surface worked as a sensing device for cholera toxin gene. The product from polymerase chain reaction (PCR) with designed primer hybridized specifically to ssDNA probe on microcantilever. The interaction between those reaction partners induced structural stress on microcantilever beam and then caused the alteration of its resistance. The DNA sensor chip was examined with PCR product from V. cholerae. The result demonstrated that the resistance of microcantilever increased from 1.3 Ω to 4.9 Ω after the hybridization of PCR product to specific probe.