The performance of the graphene-based field-effect transistor (FET) as a biosensor is based on th... more The performance of the graphene-based field-effect transistor (FET) as a biosensor is based on the output drain current (Id). In this work, the signal-to-noise ratio (SNR) was investigated to obtain a high-performance device that produces a higher Id value. Using the finite element method, a novel top-gate FET was developed in a three-dimensional (3D) simulation model with the titanium dioxide-reduced graphene oxide (TiO2-rGO) nanocomposite as the transducer material, which acts as a platform for biosensing application. Using the Taguchi mixed-level method in Minitab software (Version 16.1.1), eighteen 3D models were designed based on an orthogonal array L18 (6134), with five factors, and three and six levels. The parameters considered were the channel length, electrode length, electrode width, electrode thickness and electrode type. The device was fabricated using the conventional photolithography patterning technique and the metal lift-off method. The material was synthesised usin...
Infectious diseases are the world’s greatest killers, accounting for millions of deaths worldwide... more Infectious diseases are the world’s greatest killers, accounting for millions of deaths worldwide annually, especially in low-income countries. As the risk of emerging infectious diseases is increasing, it is critical to rapidly diagnose infections in the early stages and prevent further transmission. However, current detection strategies are time-consuming and have exhibited low sensitivity. Numerous studies revealed the advantages of point-of-care testing, such as those which are rapid, user-friendly and have high sensitivity and specificity, and can be performed at a patient’s bedside. The Lateral Flow Immunoassay (LFIA) is the most popular diagnostic assay that fulfills the POCT standards. However, conventional AuNPs-LFIAs are moderately sensitive, meaning that rapid detection remains a challenge. Here, we review quantum dot (QDs)-based LFIA for highly sensitive rapid diagnosis of infectious diseases. We briefly describe the principles of LFIA, strategies for applying QDs to enh...
Pembangunan vaksin yang berkesan adalah dianggap satu kaedah utama dalam kawalan terhadap tuberku... more Pembangunan vaksin yang berkesan adalah dianggap satu kaedah utama dalam kawalan terhadap tuberkulosis di seluruh dunia. Fokus utama projek ini ialah protein MTP40 pada M. tuberculosis yang telah di/aporkan sebelum ini mengandungi keduadua epitop sel S dan sel T. Dalam kajian ini gerak balas keimunan terhadap 7 peptida yang diterbitkan daripada protein MTP40 dalam M. tuberculosis telah diuji dengan kaedah "enzyme linked immunosorbent assay" (ELISA) dan "Iymphoblastic transformation test" (L TT) menggunakan spesimen pesakit TS (TS), individu yang terdedah kepada TS tanpa gejala (HC) dan individu kawalan (NC). Gerak balas antibodi terhadap peptida MTP40 secara umumnya didapati lebih tinggi dalam kumpulan TS berbanding dengan kumpulan HC tetapi hanya peptida P1 dan P2 yang memberikan perbezaan yang signifikan pada kedua-dua kumpulan tersebut. Di samping itu, gerak balas limfosit terhadap peptida tersebut adalah lebih tinggi di kalangan individu kumpulan HC berbandin...
Melioidosis is an infectious disease caused by the environmental bacterium <i>Burkholderia ... more Melioidosis is an infectious disease caused by the environmental bacterium <i>Burkholderia pseudomallei </i>(<i>B. pseudomallei</i>). Although the culture method is the gold standard, it cannot apply to fast on-site testing because it requires a long time. Therefore, a rapid, sensitive, and cost-effective method is highly desirable to develop for the detection of <i>B. pseudomallei</i>. In recent years, aptasensor has been widely used to detect pathogens as it is a rapid, sensitive, precise, and low-cost detection technique. We aimed to use an <i>in-silico </i>approach to overcome the inevitable shortcoming of SELEX and predict DNA aptamers with high affinity and selectivity against <i>Burkholderia </i>invasion protein D (BipD) for the detection of <i>B. pseudomallei</i>. The complex secondary structure of DNA aptamers was discovered with minimum Gibbs free energy via the mFold webserver to generate a stable ter...
Schistosomiasis caused by water related trematode Schistosoma mansoni is a serious public health ... more Schistosomiasis caused by water related trematode Schistosoma mansoni is a serious public health problem in tropical and subtropical countries. It is associated with considerable morbidity and mortality in developing and underdeveloped countries. This study aims to develop Linear-After-The-ExponentialPolymerase Chain Reaction (LATE-PCR) dipstick for the detection of Schistosoma mansoni in stool samples. In an effort to establish and enhance accurate diagnosis of Schistosoma mansoni infection, LATE-PCR dipstick was used to detect the parasite in stool samples due to the test being highly sensitive and specific, relatively simple, rapid, easy to perform. Primers and probes targeting for gene cytochrome oxidase were designed for species specific amplification of Schistosoma mansoni. In this study, the LATE-PCR dipstick parameters were optimized and detection of PCR products was performed on 2% agarose gel electrophoresis and the nitrocellulose membrane was coated with biotinylated anti...
Melioidosis and leptospirosis, caused by two different bacteria, Burkholderia pseudomallei and Le... more Melioidosis and leptospirosis, caused by two different bacteria, Burkholderia pseudomallei and Leptospira spp., are potentially fatal infections that share a very similar spectrum of clinical features and cause significant mortality and morbidity in humans and livestock. Early detection is important for better clinical consequences. To our knowledge, there is no diagnostic tool available to simultaneously detect and differentiate melioidosis and leptospirosis in humans and animals. In this study, we described a duplex TaqMan probe-based qPCR for the detection of B. pseudomallei and Leptospira spp. DNA. The performance of the assay was evaluated on 20 B. pseudomallei isolates, 23 Leptospira strains, and 39 other microorganisms, as well as two sets of serially diluted reference strains. The duplex qPCR assay was able to detect 0.02 pg (~ 4 copies) Leptospira spp. DNA and 0.2 pg (~ 25.6 copies) B. pseudomallei DNA. No undesired amplification was observed in other microorganisms. In con...
Since 2000, the widespread adoption of pneumococcal conjugate vaccines (PCVs) has had a major imp... more Since 2000, the widespread adoption of pneumococcal conjugate vaccines (PCVs) has had a major impact in the prevention of pneumonia. Limited access to international financial support means some middle-income countries (MICs) are trailing in the widespread use of PCVs. We review the status of PCV implementation, and discuss any needs and gaps related to low levels of PCV implementation in MICs, with analysis of possible solutions to strengthen the PCV implementation process in MICs. We searched PubMed, PubMed Central, Ovid MEDLINE, and SCOPUS databases using search terms related to pneumococcal immunization, governmental health policy or programmes, and MICs. Two authors independently reviewed the full text of the references, which were assessed for eligibility using pre-defined inclusion and exclusion criteria. The search terms identified 1,165 articles and the full texts of 21 were assessed for suitability, with eight articles included in the systematic review. MICs are implementin...
The development of rapid, accurate, and efficient detection methods for Salmonella can significan... more The development of rapid, accurate, and efficient detection methods for Salmonella can significantly control the outbreak of salmonellosis that threatens global public health. Despite the high sensitivity and specificity of the microbiological, nucleic-acid, and immunological-based methods, they are impractical for detecting samples outside of the laboratory due to the requirement for skilled individuals and sophisticated bench-top equipment. Ideally, an electrochemical biosensor could overcome the limitations of these detection methods since it offers simplicity for the detection process, on-site quantitative analysis, rapid detection time, high sensitivity, and portability. The present scoping review aims to assess the current trends in electrochemical aptasensors to detect and quantify Salmonella. This review was conducted according to the latest Preferred Reporting Items for Systematic review and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. A literature s...
Recently, CRISPR-Cas system-based assays for bacterial detection have been developed. The aim of ... more Recently, CRISPR-Cas system-based assays for bacterial detection have been developed. The aim of this scoping review is to map existing evidence on the utilization of CRISPR-Cas systems in the development of bacterial detection assays. A literature search was conducted using three databases (PubMed, Scopus, and Cochrane Library) and manual searches through the references of identified full texts based on a PROSPERO-registered protocol (CRD42021289140). Studies on bacterial detection using CRISPR-Cas systems that were published before October 2021 were retrieved. The Critical Appraisal Skills Programme (CASP) qualitative checklist was used to assess the risk of bias for all the included studies. Of the 420 studies identified throughout the search, 46 studies that met the inclusion criteria were included in the final analysis. Bacteria from 17 genera were identified utilising CRISPR-Cas systems. Most of the bacteria came from genera such as Staphylococcus, Escherichia, Salmonella, Lis...
International Journal of Environmental Research and Public Health
Water- and food-related health issues have received a lot of attention recently because food-pois... more Water- and food-related health issues have received a lot of attention recently because food-poisoning bacteria, in particular, are becoming serious threats to human health. Currently, techniques used to detect these bacteria are time-consuming and laborious. To overcome these challenges, the colorimetric strategy is attractive because it provides simple, rapid and accurate sensing for the detection of Salmonella spp. bacteria. The aim of this study is to review the progress regarding the colorimetric method of nucleic acid for Salmonella detection. A literature search was conducted using three databases (PubMed, Scopus and ScienceDirect). Of the 88 studies identified in our search, 15 were included for further analysis. Salmonella bacteria from different species, such as S. Typhimurium, S. Enteritidis, S. Typhi and S. Paratyphi A, were identified using the colorimetric method. The limit of detection (LoD) was evaluated in two types of concentrations, which were colony-forming unit ...
The development of precise and efficient diagnostic tools enables early treatment and proper isol... more The development of precise and efficient diagnostic tools enables early treatment and proper isolation of infected individuals, hence limiting the spread of coronavirus disease 2019 (COVID-19). The standard diagnostic tests used by healthcare workers to diagnose severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection have some limitations, including longer detection time, the need for qualified individuals, and the use of sophisticated bench-top equipment, which limit their use for rapid SARS-CoV-2 assessment. Advances in sensor technology have renewed the interest in electrochemical biosensors miniaturization, which provide improved diagnostic qualities such as rapid response, simplicity of operation, portability, and readiness for on-site screening of infection. This review gives a condensed overview of the current electrochemical sensing platform strategies for SARS-CoV-2 detection in clinical samples. The fundamentals of fabricating electrochemical biosensors, suc...
Introduction: Methylation of promoter region of p16 leading to gene silencing has been implicated... more Introduction: Methylation of promoter region of p16 leading to gene silencing has been implicated in a wide range of malignancies including lymphomas. In diffuse large B cell lymphoma (DLBCL) particularly, a varying percentage of epigenetic inactivation of p16 promoter region was observed ranging from 16 - 54%. However, quantitative analysis of p16 promoter methylation in DLBCL has not been extensively studied in Malaysia. Objective: This study aims to quantitatively analyse p16 methylation in DLBCL samples using pyrosequencing technique. Methods: Genomic DNA was extracted from 16 formalin-fixed paraffin-embedded lymphoma tissue blocks from patients diagnosed with DLBCL. Samples were retrieved from Hospital Tengku Ampuan Afzan, Pahang and Hospital Universiti Sains Malaysia, Kelantan. Primers were designed to amplify bisulfite-treated DNA targeting p16 promoter region. Methylation status of 7 CpG sites was determined by pyrosequencing. Results: All the 16 samples studied showed promo...
Avian influenza (AI), caused by the avian strain of influenza A virus (AIV) is one of the signifi... more Avian influenza (AI), caused by the avian strain of influenza A virus (AIV) is one of the significant health concerns globally. Human infections with AI viruses were reported sporadically and often exhibited high mortality and morbidity rate. AI outbreaks also influenced the safety of the food supply and caused significant economic losses. Immediate control measures are required during AI outbreaks in poultry to prevent further viruses spreading. Hence, accurate, sensitive, and rapid detection methods are pivotal for decision making. Traditional methods of detection, such as virus isolation in embryonated chicken eggs, immuno-based methods, and nucleic acid amplification method, pose different limitations. These always grab the attention of researchers to improve existing methods or invent novel diagnostic approaches to compensate for the shortcoming of current methods applied. However, the method of choice is highly dependent on the availability of facilities and resources. Among the detection methods, reverse transcription-polymerase chain reaction (RT-PCR) is the most favourable method used for detecting AIV. However, a constant review of the virus genome is crucial to maintain the assay's sensitivity. More comprehensive research and evaluation study are needed for new diagnostic approaches.
The Gram-negative pathogenic spirochetal bacteria Leptospira spp. cause leptospirosis in humans a... more The Gram-negative pathogenic spirochetal bacteria Leptospira spp. cause leptospirosis in humans and livestock animals. Leptospira kmetyi strain LS 001/16 was isolated from a soil sample associated with a leptospirosis patient in Kelantan, which is among the states in Malaysia with a high reported number of disease cases. Here, we report the complete genome sequence of Leptospira kmetyi strain LS 001/16.
Melioidosis is a severe disease caused by Burkholderia pseudomallei (B. pseudomallei), a Gram-neg... more Melioidosis is a severe disease caused by Burkholderia pseudomallei (B. pseudomallei), a Gram-negative environmental bacterium. It is endemic in Southeast Asia and Northern Australia, but it is underreported in many other countries. The principal routes of entry for B. pseudomallei are skin penetration, inhalation, and ingestion. It mainly affects immunocompromised populations, especially patients with type 2 diabetes mellitus. The laboratory diagnosis of melioidosis is challenging due to its non-specific clinical manifestations, which mimic other severe infections. The culture method is considered an imperfect gold standard for the diagnosis of melioidosis due to its low sensitivity. Antibody detection has low sensitivity and specificity due to the high seropositivity among healthy people in endemic regions. Antigen detection using various proteins has been tested for the rapid determination of B. pseudomallei; however, it presents certain limitations in terms of its sensitivity an...
In this paper, a novel oscillating flow polymerase chain reaction ͑PCR͒ device was designed and f... more In this paper, a novel oscillating flow polymerase chain reaction ͑PCR͒ device was designed and fabricated to amplify SPPS150 and salmonella typhi. In this new design, the samples are shuttled ͑oscillating flow͒ inside a microfluidic chip to three different temperature zones required for DNA amplification. The amplification cycle time has markedly been reduced as the reagent volume used was only about 25% of that used in conventional PCRs. Bubble formation and adsorption issues commonly associated to chip based PCR were also eliminated. Based on the performance evaluated, it is demonstrated that this oscillating flow PCR has the advantages of both the stationary chamber and continuous flow PCR devices.
International Journal of Environmental Research and Public Health
This study is a cross-sectional, observational analysis of the COVID-19 pandemic in Africa, to un... more This study is a cross-sectional, observational analysis of the COVID-19 pandemic in Africa, to understand the progression of the disease across the continent. Published data on COVID-19 from 20 January 2020 to 21 June 2021 were obtained and analyzed. Case fatality ratios, as well as case growth rates and other indices were computed. On 21 June 2021, a total of 178,210,532 confirmed cases and 3,865,978 deaths had been recorded worldwide. While the Americas recorded the highest number of cases, Southern Africa recorded the majority of African cases. Fatality rate since from 20 February 2020 to 21 June 2021 was highest in the Americas (2.63%) and low in the South Eastern Asia region (1.39%), globally increasing from 2.17% at the end of January to 6.36% in May 2020 and decreasing to a range between 2.14% to 2.30% since January 2021. In Africa, the infection rate per 100,000 persons was up to 3090.18, while deaths per 100,000 and case fatality ratio were as high as 119.64 and 5.72%, resp...
Large-scale food-borne outbreaks caused by Salmonella are rarely seen nowadays, thanks to the adv... more Large-scale food-borne outbreaks caused by Salmonella are rarely seen nowadays, thanks to the advanced nature of the medical system. However, small, localised outbreaks in certain regions still exist and could possess a huge threat to the public health if eradication measure is not initiated. This review discusses the progress of Salmonella detection approaches covering their basic principles, characteristics, applications, and performances. Conventional Salmonella detection is usually performed using a culture-based method, which is time-consuming, labour intensive, and unsuitable for on-site testing and high-throughput analysis. To date, there are many detection methods with a unique detection system available for Salmonella detection utilising immunological-based techniques, molecular-based techniques, mass spectrometry, spectroscopy, optical phenotyping, and biosensor methods. The electrochemical biosensor has growing interest in Salmonella detection mainly due to its excellent ...
A multiplex rapid detection system, based on a PCR-lateral flow biosensor (mPCR-LFB) was develope... more A multiplex rapid detection system, based on a PCR-lateral flow biosensor (mPCR-LFB) was developed to identify Salmonella Typhi and Salmonella Paratyphi A from suspected carriers. The lower detection limit for S. Typhi and S. Paratyphi A was 0.16 and 0.08 ng DNA equivalent to 10 and 102 CFU/mL, respectively. Lateral flow biosensor was used for visual detection of mPCR amplicons (stgA, SPAint, ompC, internal amplification control) by labeling forward primers with fluorescein-isothiocyanate (FITC), Texas Red, dinitrophenol (DNP) and digoxigenin (DIG) and reverse primers with biotin. Binding of streptavidin-colloidal gold conjugate with the amplicons resulted in formation of a red color dots on the strip after 15–20 min of sample exposure. The nucleic acid lateral flow analysis of the mPCR-LFB was better in sensitivity and more rapid than the conventional agarose gel electrophoresis. Moreover, the mPCR-LFB showed 100% sensitivity and specificity when evaluated with stools spiked with 1...
Typhoid fever, also known as typhoid, is a life-threatening bacterial infection that remains a gl... more Typhoid fever, also known as typhoid, is a life-threatening bacterial infection that remains a global health concern. The infection is associated with a significant morbidity and mortality rate, resulting in an urgent need for specific and rapid detection tests to aid prevention and management of the disease. The present review aims to assess the specificity and sensitivity of the available literature on the immunodiagnostics of typhoid fever. A literature search was conducted using three databases (PubMed, ProQuest and Scopus) and manual searches through the references of identified full texts to retrieve relevant literature published between 1 January 2011 and 31 December 2020. Of the 577 studies identified in our search, 12 were included in further analysis. Lipopolysaccharides (LPS) and hemolysin E (HlyE) were the most frequently studied antigens. The specimens examined in these studies included serum and saliva. Using blood culture as the gold standard, anti-LPS IgA gave the hi...
The performance of the graphene-based field-effect transistor (FET) as a biosensor is based on th... more The performance of the graphene-based field-effect transistor (FET) as a biosensor is based on the output drain current (Id). In this work, the signal-to-noise ratio (SNR) was investigated to obtain a high-performance device that produces a higher Id value. Using the finite element method, a novel top-gate FET was developed in a three-dimensional (3D) simulation model with the titanium dioxide-reduced graphene oxide (TiO2-rGO) nanocomposite as the transducer material, which acts as a platform for biosensing application. Using the Taguchi mixed-level method in Minitab software (Version 16.1.1), eighteen 3D models were designed based on an orthogonal array L18 (6134), with five factors, and three and six levels. The parameters considered were the channel length, electrode length, electrode width, electrode thickness and electrode type. The device was fabricated using the conventional photolithography patterning technique and the metal lift-off method. The material was synthesised usin...
Infectious diseases are the world’s greatest killers, accounting for millions of deaths worldwide... more Infectious diseases are the world’s greatest killers, accounting for millions of deaths worldwide annually, especially in low-income countries. As the risk of emerging infectious diseases is increasing, it is critical to rapidly diagnose infections in the early stages and prevent further transmission. However, current detection strategies are time-consuming and have exhibited low sensitivity. Numerous studies revealed the advantages of point-of-care testing, such as those which are rapid, user-friendly and have high sensitivity and specificity, and can be performed at a patient’s bedside. The Lateral Flow Immunoassay (LFIA) is the most popular diagnostic assay that fulfills the POCT standards. However, conventional AuNPs-LFIAs are moderately sensitive, meaning that rapid detection remains a challenge. Here, we review quantum dot (QDs)-based LFIA for highly sensitive rapid diagnosis of infectious diseases. We briefly describe the principles of LFIA, strategies for applying QDs to enh...
Pembangunan vaksin yang berkesan adalah dianggap satu kaedah utama dalam kawalan terhadap tuberku... more Pembangunan vaksin yang berkesan adalah dianggap satu kaedah utama dalam kawalan terhadap tuberkulosis di seluruh dunia. Fokus utama projek ini ialah protein MTP40 pada M. tuberculosis yang telah di/aporkan sebelum ini mengandungi keduadua epitop sel S dan sel T. Dalam kajian ini gerak balas keimunan terhadap 7 peptida yang diterbitkan daripada protein MTP40 dalam M. tuberculosis telah diuji dengan kaedah "enzyme linked immunosorbent assay" (ELISA) dan "Iymphoblastic transformation test" (L TT) menggunakan spesimen pesakit TS (TS), individu yang terdedah kepada TS tanpa gejala (HC) dan individu kawalan (NC). Gerak balas antibodi terhadap peptida MTP40 secara umumnya didapati lebih tinggi dalam kumpulan TS berbanding dengan kumpulan HC tetapi hanya peptida P1 dan P2 yang memberikan perbezaan yang signifikan pada kedua-dua kumpulan tersebut. Di samping itu, gerak balas limfosit terhadap peptida tersebut adalah lebih tinggi di kalangan individu kumpulan HC berbandin...
Melioidosis is an infectious disease caused by the environmental bacterium <i>Burkholderia ... more Melioidosis is an infectious disease caused by the environmental bacterium <i>Burkholderia pseudomallei </i>(<i>B. pseudomallei</i>). Although the culture method is the gold standard, it cannot apply to fast on-site testing because it requires a long time. Therefore, a rapid, sensitive, and cost-effective method is highly desirable to develop for the detection of <i>B. pseudomallei</i>. In recent years, aptasensor has been widely used to detect pathogens as it is a rapid, sensitive, precise, and low-cost detection technique. We aimed to use an <i>in-silico </i>approach to overcome the inevitable shortcoming of SELEX and predict DNA aptamers with high affinity and selectivity against <i>Burkholderia </i>invasion protein D (BipD) for the detection of <i>B. pseudomallei</i>. The complex secondary structure of DNA aptamers was discovered with minimum Gibbs free energy via the mFold webserver to generate a stable ter...
Schistosomiasis caused by water related trematode Schistosoma mansoni is a serious public health ... more Schistosomiasis caused by water related trematode Schistosoma mansoni is a serious public health problem in tropical and subtropical countries. It is associated with considerable morbidity and mortality in developing and underdeveloped countries. This study aims to develop Linear-After-The-ExponentialPolymerase Chain Reaction (LATE-PCR) dipstick for the detection of Schistosoma mansoni in stool samples. In an effort to establish and enhance accurate diagnosis of Schistosoma mansoni infection, LATE-PCR dipstick was used to detect the parasite in stool samples due to the test being highly sensitive and specific, relatively simple, rapid, easy to perform. Primers and probes targeting for gene cytochrome oxidase were designed for species specific amplification of Schistosoma mansoni. In this study, the LATE-PCR dipstick parameters were optimized and detection of PCR products was performed on 2% agarose gel electrophoresis and the nitrocellulose membrane was coated with biotinylated anti...
Melioidosis and leptospirosis, caused by two different bacteria, Burkholderia pseudomallei and Le... more Melioidosis and leptospirosis, caused by two different bacteria, Burkholderia pseudomallei and Leptospira spp., are potentially fatal infections that share a very similar spectrum of clinical features and cause significant mortality and morbidity in humans and livestock. Early detection is important for better clinical consequences. To our knowledge, there is no diagnostic tool available to simultaneously detect and differentiate melioidosis and leptospirosis in humans and animals. In this study, we described a duplex TaqMan probe-based qPCR for the detection of B. pseudomallei and Leptospira spp. DNA. The performance of the assay was evaluated on 20 B. pseudomallei isolates, 23 Leptospira strains, and 39 other microorganisms, as well as two sets of serially diluted reference strains. The duplex qPCR assay was able to detect 0.02 pg (~ 4 copies) Leptospira spp. DNA and 0.2 pg (~ 25.6 copies) B. pseudomallei DNA. No undesired amplification was observed in other microorganisms. In con...
Since 2000, the widespread adoption of pneumococcal conjugate vaccines (PCVs) has had a major imp... more Since 2000, the widespread adoption of pneumococcal conjugate vaccines (PCVs) has had a major impact in the prevention of pneumonia. Limited access to international financial support means some middle-income countries (MICs) are trailing in the widespread use of PCVs. We review the status of PCV implementation, and discuss any needs and gaps related to low levels of PCV implementation in MICs, with analysis of possible solutions to strengthen the PCV implementation process in MICs. We searched PubMed, PubMed Central, Ovid MEDLINE, and SCOPUS databases using search terms related to pneumococcal immunization, governmental health policy or programmes, and MICs. Two authors independently reviewed the full text of the references, which were assessed for eligibility using pre-defined inclusion and exclusion criteria. The search terms identified 1,165 articles and the full texts of 21 were assessed for suitability, with eight articles included in the systematic review. MICs are implementin...
The development of rapid, accurate, and efficient detection methods for Salmonella can significan... more The development of rapid, accurate, and efficient detection methods for Salmonella can significantly control the outbreak of salmonellosis that threatens global public health. Despite the high sensitivity and specificity of the microbiological, nucleic-acid, and immunological-based methods, they are impractical for detecting samples outside of the laboratory due to the requirement for skilled individuals and sophisticated bench-top equipment. Ideally, an electrochemical biosensor could overcome the limitations of these detection methods since it offers simplicity for the detection process, on-site quantitative analysis, rapid detection time, high sensitivity, and portability. The present scoping review aims to assess the current trends in electrochemical aptasensors to detect and quantify Salmonella. This review was conducted according to the latest Preferred Reporting Items for Systematic review and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. A literature s...
Recently, CRISPR-Cas system-based assays for bacterial detection have been developed. The aim of ... more Recently, CRISPR-Cas system-based assays for bacterial detection have been developed. The aim of this scoping review is to map existing evidence on the utilization of CRISPR-Cas systems in the development of bacterial detection assays. A literature search was conducted using three databases (PubMed, Scopus, and Cochrane Library) and manual searches through the references of identified full texts based on a PROSPERO-registered protocol (CRD42021289140). Studies on bacterial detection using CRISPR-Cas systems that were published before October 2021 were retrieved. The Critical Appraisal Skills Programme (CASP) qualitative checklist was used to assess the risk of bias for all the included studies. Of the 420 studies identified throughout the search, 46 studies that met the inclusion criteria were included in the final analysis. Bacteria from 17 genera were identified utilising CRISPR-Cas systems. Most of the bacteria came from genera such as Staphylococcus, Escherichia, Salmonella, Lis...
International Journal of Environmental Research and Public Health
Water- and food-related health issues have received a lot of attention recently because food-pois... more Water- and food-related health issues have received a lot of attention recently because food-poisoning bacteria, in particular, are becoming serious threats to human health. Currently, techniques used to detect these bacteria are time-consuming and laborious. To overcome these challenges, the colorimetric strategy is attractive because it provides simple, rapid and accurate sensing for the detection of Salmonella spp. bacteria. The aim of this study is to review the progress regarding the colorimetric method of nucleic acid for Salmonella detection. A literature search was conducted using three databases (PubMed, Scopus and ScienceDirect). Of the 88 studies identified in our search, 15 were included for further analysis. Salmonella bacteria from different species, such as S. Typhimurium, S. Enteritidis, S. Typhi and S. Paratyphi A, were identified using the colorimetric method. The limit of detection (LoD) was evaluated in two types of concentrations, which were colony-forming unit ...
The development of precise and efficient diagnostic tools enables early treatment and proper isol... more The development of precise and efficient diagnostic tools enables early treatment and proper isolation of infected individuals, hence limiting the spread of coronavirus disease 2019 (COVID-19). The standard diagnostic tests used by healthcare workers to diagnose severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection have some limitations, including longer detection time, the need for qualified individuals, and the use of sophisticated bench-top equipment, which limit their use for rapid SARS-CoV-2 assessment. Advances in sensor technology have renewed the interest in electrochemical biosensors miniaturization, which provide improved diagnostic qualities such as rapid response, simplicity of operation, portability, and readiness for on-site screening of infection. This review gives a condensed overview of the current electrochemical sensing platform strategies for SARS-CoV-2 detection in clinical samples. The fundamentals of fabricating electrochemical biosensors, suc...
Introduction: Methylation of promoter region of p16 leading to gene silencing has been implicated... more Introduction: Methylation of promoter region of p16 leading to gene silencing has been implicated in a wide range of malignancies including lymphomas. In diffuse large B cell lymphoma (DLBCL) particularly, a varying percentage of epigenetic inactivation of p16 promoter region was observed ranging from 16 - 54%. However, quantitative analysis of p16 promoter methylation in DLBCL has not been extensively studied in Malaysia. Objective: This study aims to quantitatively analyse p16 methylation in DLBCL samples using pyrosequencing technique. Methods: Genomic DNA was extracted from 16 formalin-fixed paraffin-embedded lymphoma tissue blocks from patients diagnosed with DLBCL. Samples were retrieved from Hospital Tengku Ampuan Afzan, Pahang and Hospital Universiti Sains Malaysia, Kelantan. Primers were designed to amplify bisulfite-treated DNA targeting p16 promoter region. Methylation status of 7 CpG sites was determined by pyrosequencing. Results: All the 16 samples studied showed promo...
Avian influenza (AI), caused by the avian strain of influenza A virus (AIV) is one of the signifi... more Avian influenza (AI), caused by the avian strain of influenza A virus (AIV) is one of the significant health concerns globally. Human infections with AI viruses were reported sporadically and often exhibited high mortality and morbidity rate. AI outbreaks also influenced the safety of the food supply and caused significant economic losses. Immediate control measures are required during AI outbreaks in poultry to prevent further viruses spreading. Hence, accurate, sensitive, and rapid detection methods are pivotal for decision making. Traditional methods of detection, such as virus isolation in embryonated chicken eggs, immuno-based methods, and nucleic acid amplification method, pose different limitations. These always grab the attention of researchers to improve existing methods or invent novel diagnostic approaches to compensate for the shortcoming of current methods applied. However, the method of choice is highly dependent on the availability of facilities and resources. Among the detection methods, reverse transcription-polymerase chain reaction (RT-PCR) is the most favourable method used for detecting AIV. However, a constant review of the virus genome is crucial to maintain the assay's sensitivity. More comprehensive research and evaluation study are needed for new diagnostic approaches.
The Gram-negative pathogenic spirochetal bacteria Leptospira spp. cause leptospirosis in humans a... more The Gram-negative pathogenic spirochetal bacteria Leptospira spp. cause leptospirosis in humans and livestock animals. Leptospira kmetyi strain LS 001/16 was isolated from a soil sample associated with a leptospirosis patient in Kelantan, which is among the states in Malaysia with a high reported number of disease cases. Here, we report the complete genome sequence of Leptospira kmetyi strain LS 001/16.
Melioidosis is a severe disease caused by Burkholderia pseudomallei (B. pseudomallei), a Gram-neg... more Melioidosis is a severe disease caused by Burkholderia pseudomallei (B. pseudomallei), a Gram-negative environmental bacterium. It is endemic in Southeast Asia and Northern Australia, but it is underreported in many other countries. The principal routes of entry for B. pseudomallei are skin penetration, inhalation, and ingestion. It mainly affects immunocompromised populations, especially patients with type 2 diabetes mellitus. The laboratory diagnosis of melioidosis is challenging due to its non-specific clinical manifestations, which mimic other severe infections. The culture method is considered an imperfect gold standard for the diagnosis of melioidosis due to its low sensitivity. Antibody detection has low sensitivity and specificity due to the high seropositivity among healthy people in endemic regions. Antigen detection using various proteins has been tested for the rapid determination of B. pseudomallei; however, it presents certain limitations in terms of its sensitivity an...
In this paper, a novel oscillating flow polymerase chain reaction ͑PCR͒ device was designed and f... more In this paper, a novel oscillating flow polymerase chain reaction ͑PCR͒ device was designed and fabricated to amplify SPPS150 and salmonella typhi. In this new design, the samples are shuttled ͑oscillating flow͒ inside a microfluidic chip to three different temperature zones required for DNA amplification. The amplification cycle time has markedly been reduced as the reagent volume used was only about 25% of that used in conventional PCRs. Bubble formation and adsorption issues commonly associated to chip based PCR were also eliminated. Based on the performance evaluated, it is demonstrated that this oscillating flow PCR has the advantages of both the stationary chamber and continuous flow PCR devices.
International Journal of Environmental Research and Public Health
This study is a cross-sectional, observational analysis of the COVID-19 pandemic in Africa, to un... more This study is a cross-sectional, observational analysis of the COVID-19 pandemic in Africa, to understand the progression of the disease across the continent. Published data on COVID-19 from 20 January 2020 to 21 June 2021 were obtained and analyzed. Case fatality ratios, as well as case growth rates and other indices were computed. On 21 June 2021, a total of 178,210,532 confirmed cases and 3,865,978 deaths had been recorded worldwide. While the Americas recorded the highest number of cases, Southern Africa recorded the majority of African cases. Fatality rate since from 20 February 2020 to 21 June 2021 was highest in the Americas (2.63%) and low in the South Eastern Asia region (1.39%), globally increasing from 2.17% at the end of January to 6.36% in May 2020 and decreasing to a range between 2.14% to 2.30% since January 2021. In Africa, the infection rate per 100,000 persons was up to 3090.18, while deaths per 100,000 and case fatality ratio were as high as 119.64 and 5.72%, resp...
Large-scale food-borne outbreaks caused by Salmonella are rarely seen nowadays, thanks to the adv... more Large-scale food-borne outbreaks caused by Salmonella are rarely seen nowadays, thanks to the advanced nature of the medical system. However, small, localised outbreaks in certain regions still exist and could possess a huge threat to the public health if eradication measure is not initiated. This review discusses the progress of Salmonella detection approaches covering their basic principles, characteristics, applications, and performances. Conventional Salmonella detection is usually performed using a culture-based method, which is time-consuming, labour intensive, and unsuitable for on-site testing and high-throughput analysis. To date, there are many detection methods with a unique detection system available for Salmonella detection utilising immunological-based techniques, molecular-based techniques, mass spectrometry, spectroscopy, optical phenotyping, and biosensor methods. The electrochemical biosensor has growing interest in Salmonella detection mainly due to its excellent ...
A multiplex rapid detection system, based on a PCR-lateral flow biosensor (mPCR-LFB) was develope... more A multiplex rapid detection system, based on a PCR-lateral flow biosensor (mPCR-LFB) was developed to identify Salmonella Typhi and Salmonella Paratyphi A from suspected carriers. The lower detection limit for S. Typhi and S. Paratyphi A was 0.16 and 0.08 ng DNA equivalent to 10 and 102 CFU/mL, respectively. Lateral flow biosensor was used for visual detection of mPCR amplicons (stgA, SPAint, ompC, internal amplification control) by labeling forward primers with fluorescein-isothiocyanate (FITC), Texas Red, dinitrophenol (DNP) and digoxigenin (DIG) and reverse primers with biotin. Binding of streptavidin-colloidal gold conjugate with the amplicons resulted in formation of a red color dots on the strip after 15–20 min of sample exposure. The nucleic acid lateral flow analysis of the mPCR-LFB was better in sensitivity and more rapid than the conventional agarose gel electrophoresis. Moreover, the mPCR-LFB showed 100% sensitivity and specificity when evaluated with stools spiked with 1...
Typhoid fever, also known as typhoid, is a life-threatening bacterial infection that remains a gl... more Typhoid fever, also known as typhoid, is a life-threatening bacterial infection that remains a global health concern. The infection is associated with a significant morbidity and mortality rate, resulting in an urgent need for specific and rapid detection tests to aid prevention and management of the disease. The present review aims to assess the specificity and sensitivity of the available literature on the immunodiagnostics of typhoid fever. A literature search was conducted using three databases (PubMed, ProQuest and Scopus) and manual searches through the references of identified full texts to retrieve relevant literature published between 1 January 2011 and 31 December 2020. Of the 577 studies identified in our search, 12 were included in further analysis. Lipopolysaccharides (LPS) and hemolysin E (HlyE) were the most frequently studied antigens. The specimens examined in these studies included serum and saliva. Using blood culture as the gold standard, anti-LPS IgA gave the hi...
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Papers by Aziah Ismail