Publications by authors named "Toh Leong Tan"

11 Publications

  • Page 1 of 1

Methicillin-Resistant (MRSA) Clonal Replacement in a Malaysian Teaching Hospital: Findings from an Eight-Year Interval Molecular Surveillance.

Antibiotics (Basel) 2021 Mar 19;10(3). Epub 2021 Mar 19.

UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Kuala Lumpur 56000, Malaysia.

Periodical surveillance on nosocomial pathogens is important for antimicrobial stewardship and infection control. The first methicillin-resistant (MRSA) molecular surveillance in Hospital Canselor Tuanku Muhriz (HCTM), a Malaysian teaching hospital, was performed in 2009. The dominant clone was identified as an MRSA carrying SCC type III-SCC with and + toxin genes. In this study, we report the findings of the second HCTM MRSA surveillance carried out in 2017, after an interval of 8 years. Antibiotic susceptibility testing, SCC, toxin gene, and typing were performed for 222 MRSA strains isolated in 2017. Most strains were resistant to ciprofloxacin, erythromycin, clindamycin, cefoxitin, and penicillin ( = 126, 56.8%), belong to SCC type IV ( = 205, 92.3%), type t032 ( = 160, 72.1%) and harboured + toxin genes ( = 172, 77.5%). There was significant association between resistance of the aforementioned antibiotics with SCC type IV ( < 0.05), t032 ( < 0.001), and + carriage ( < 0.05). Results from this second MRSA surveillance revealed the occurrence of clonal replacement in HCTM during an interval of not more than 8 years. Investigation of the corresponding phenotype changes in this new dominant MRSA clone is currently on-going.
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http://dx.doi.org/10.3390/antibiotics10030320DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8003425PMC
March 2021

Advantages and Limitations of 16S rRNA Next-Generation Sequencing for Pathogen Identification in the Diagnostic Microbiology Laboratory: Perspectives from a Middle-Income Country.

Diagnostics (Basel) 2020 Oct 14;10(10). Epub 2020 Oct 14.

BioEasy Sdn. Bhd., Selangor 40170, Malaysia.

Bacterial culture and biochemical testing (CBtest) have been the cornerstone of pathogen identification in the diagnostic microbiology laboratory. With the advent of Sanger sequencing and later, next-generation sequencing, 16S rRNA next-generation sequencing (16SNGS) has been proposed to be a plausible platform for this purpose. Nevertheless, usage of the 16SNGS platform has both advantages and limitations. In addition, transition from the traditional methods of CBtest to 16SNGS requires procurement of costly equipment, timely and sustainable maintenance of these platforms, specific facility infrastructure and technical expertise. All these factors pose a challenge for middle-income countries, more so for countries in the lower middle-income range. In this review, we describe the basis for CBtest and 16SNGS, and discuss the limitations, challenges, advantages and future potential of using 16SNGS for bacterial pathogen identification in diagnostic microbiology laboratories of middle-income countries.
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http://dx.doi.org/10.3390/diagnostics10100816DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7602188PMC
October 2020

Molecular surveillance of methicillin-susceptible (MSSA) isolated over a one-year period from a Malaysian Teaching Hospital.

Germs 2020 Jun 2;10(2):104-111. Epub 2020 Jun 2.

PhD, UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Cheras, 56000 Kuala Lumpur, Malaysia.

Introduction: We report the results of a molecular surveillance study carried out on methicillin-susceptible (MSSA) isolated in a one-year duration from Hospital Canselor Tuanku Muhriz (HCTM), a tertiary hospital located in Kuala Lumpur, Malaysia.

Methods: The first strain isolated from each MSSA infection in HCTM during the year 2009 was included into the study. Antimicrobial susceptibility testing and agr group typing were carried out for all strains; virulence gene (, , TSST-1 and PVL) typing results of the strains were obtained from a previous study. Pulsed-field gel electrophoresis (PFGE) was done on selected strains from the orthopedic ward. Relationship(s) between different typing methods used in the study was investigated, where a p value of <0.05 indicated significant association between typing methods.

Results: A total of 880 MSSA strains were included into the study. The strains were generally susceptible to most antibiotics, with most of them carrying and -I (51.6%, n=454; 39.8%, n=350, respectively). A total of 17 PFGE pulsotypes were identified using an 80% similarity cut-off value, where the main pulsotype (pulsotype E) consisted of 24 isolates (23.5%). -III strains were found to be usually positive for both and (p<0.05). In addition, some PFGE pulsotypes were also characteristic of certain virulence genes or groups.

Conclusions: We did not identify a dominant MSSA clone circulating in HCTM in 2009. Nevertheless, results from this molecular surveillance will provide good baseline data for the hospital's second surveillance planned for the year 2020.
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http://dx.doi.org/10.18683/germs.2020.1191DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7330523PMC
June 2020

High sPLA2-IIA level is associated with eicosanoid metabolism in patients with bacterial sepsis syndrome.

PLoS One 2020 11;15(3):e0230285. Epub 2020 Mar 11.

Biochemistry Unit, Faculty of Medicine and Defence Health, National Defence University of Malaysia, Sungai Besi Camp, Kuala Lumpur, Malaysia.

The aim of this study was to determine the association between secretory phospholipase A2 group IIA (sPLA2-IIA) and eicosanoid pathway metabolites in patients with bacterial sepsis syndrome (BSS). Levels of sPLA2-IIA, eicosanoids prostaglandin (PG)E2, PGD synthase were quantified in the sera from patients confirmed to have bacterial sepsis (BS; N = 45), bacterial severe sepsis/septic shock (BSS/SS; N = 35) and healthy subjects (N = 45). Cyclooxygenase (COX)-1 and COX-2 activities were analyzed from cell lysate. Serum levels of sPLA2-IIA, PGE2, and PGDS increased significantly in patients with BS and BSS/SS compared to healthy subjects (p<0.05). COX-2 activity was significantly increased in patients with BS compared to healthy subjects (p<0.05), but not COX-1 activity. Binary logistic regression analysis showed that sPLA2-IIA and PGE2 were independent factors predicting BSS severity. In conclusion, high level of sPLA2-IIA is associated with eicosanoid metabolism in patients with BSS.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0230285PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7065791PMC
June 2020

Pulsed-field gel electrophoresis (PFGE): A review of the "gold standard" for bacteria typing and current alternatives.

Infect Genet Evol 2019 10 22;74:103935. Epub 2019 Jun 22.

Department of Emergency Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Malaysia.

Pulsed-field gel electrophoresis (PFGE) is considered the "gold standard" for bacteria typing. The method involves enzyme restriction of bacteria DNA, separation of the restricted DNA bands using a pulsed-field electrophoresis chamber, followed by clonal assignment of bacteria based on PFGE banding patterns. Various PFGE protocols have been developed for typing different bacteria, leading it to be one of the most widely used methods for phylogenetic studies, food safety surveillance, infection control and outbreak investigations. On the other hand, as PFGE is lengthy and labourious, several PCR-based typing methods can be used as alternatives for research purposes. Recently, matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) and whole genome sequencing (WGS) have also been proposed for bacteria typing. In fact, as WGS provides more information, such as antimicrobial resistance and virulence of the tested bacteria in comparison to PFGE, more and more laboratories are currently transitioning from PFGE to WGS for bacteria typing. Nevertheless, PFGE will remain an affordable and relevant technique for small laboratories and hospitals in years to come.
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http://dx.doi.org/10.1016/j.meegid.2019.103935DOI Listing
October 2019

Rapid Detection of Sepsis using CESDA: the Caenorhabditis elegans Sepsis Detection Assay.

Rev Soc Bras Med Trop 2019 Mar 14;52:e20180300. Epub 2019 Mar 14.

UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Malaysia.

Introduction: The nematode Caenorhabditis elegans was used as a biological sensor to detect the urine of sepsis patients (CESDA assay).

Methods: C. elegans was aliquoted onto the center of assay plates and allowed to migrate towards sepsis (T) or control (C) urine samples spotted on the same plate. The number of worms found in either (T) or (C) was scored at 10-minute intervals over a 60-minute period.

Results: The worms were able to identify the urine (<48 hours) of sepsis patients rapidly within 20 minutes (AUROC=0.67, p=0.012) and infection within 40 minutes (AUROC=0.80, p=0.016).

Conclusions: CESDA could be further explored for sepsis diagnosis.
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http://dx.doi.org/10.1590/0037-8682-0300-2018DOI Listing
March 2019

Comparison of Prognostic Accuracy of the quick Sepsis-Related Organ Failure Assessment between Short- & Long-term Mortality in Patients Presenting Outside of the Intensive Care Unit - A Systematic Review & Meta-analysis.

Sci Rep 2018 11 12;8(1):16698. Epub 2018 Nov 12.

UKM Medical Molecular Biology Institute (UMBI), Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.

The purpose of this meta-analysis was to compare the ability of the qSOFA in predicting short- (≤30 days or in-hospital mortality) and long-term (>30 days) mortality among patients outside the intensive care unit setting. Studies reporting on the qSOFA and mortality were searched using MEDLINE and SCOPUS. Studies were included if they involved patients presenting to the ED with suspected infection and usage of qSOFA score for mortality prognostication. Data on qSOFA scores and mortality rates were extracted from 36 studies. The overall pooled sensitivity and specificity for the qSOFA were 48% and 86% for short-term mortality and 32% and 92% for long-term mortality, respectively. Studies reporting on short-term mortality were heterogeneous (Odd ratio, OR = 5.6; 95% CI = 4.6-6.8; Higgins's I = 94%), while long-term mortality studies were homogenous (OR = 4.7; 95% CI = 3.5-6.1; Higgins's I = 0%). There was no publication bias for short-term mortality analysis. The qSOFA score showed poor sensitivity but moderate specificity for both short and long-term mortality, with similar performance in predicting both short- and long- term mortality. Geographical region was shown to have nominal significant (p = 0.05) influence on qSOFA short-term mortality prediction.
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http://dx.doi.org/10.1038/s41598-018-35144-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6232181PMC
November 2018

The role of group IIA secretory phospholipase A2 (sPLA2-IIA) as a biomarker for the diagnosis of sepsis and bacterial infection in adults-A systematic review.

PLoS One 2017 3;12(7):e0180554. Epub 2017 Jul 3.

Department of Emergency Medicine, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.

Introduction: This paper investigates the role of Group II Secretory Phospholipase A2 (sPLA2-IIA) as a biomarker for the diagnosis of sepsis and bacterial infection in adults. Sepsis and bacterial infection are common problems encountered by patients in the hospital and often carry adverse outcomes if not managed early.

Methods: Two independent reviewers conducted a comprehensive search using Ovid MEDLINE published from years 1993 to 2016 and SCOPUS published from year 1985 to 2017 to screen for relevant studies. The main inclusion criteria included adult subjects, patients with suspected or confirmed signs of infection and relevant outcomes which looked into the role of sPLA2-IIA in detecting the presence of sepsis and bacterial infection in the subjects.

Results And Discussion: Four studies met the inclusion criteria. SPLA2-IIA was found to be effective in detecting the presence of sepsis and bacterial infection in adults. The levels of serum sPLA2-IIA also correlated well with the presence of sepsis and bacterial infection.

Conclusion: This systematic review highlights the role of sPLA2-IIA as a reliable tool to diagnose sepsis and bacterial infection in adult patients. Nonetheless, further studies should be done in the future to provide more compelling evidence on its application in the clinical setting.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0180554PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5495423PMC
October 2017

Antimicrobial resistance profiling and molecular typing of methicillin-resistant Staphylococcus aureus isolated from a Malaysian teaching hospital.

J Med Microbiol 2016 Dec 7;65(12):1476-1481. Epub 2016 Nov 7.

Department of Medical Microbiology & Immunology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.

The annual prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in Malaysia has been estimated to be 30 % to 40 % of all S. aureus infections. Nevertheless, data on the antimicrobial resistance and genetic diversity of Malaysian MRSAs remain few. In 2009, we collected 318 MRSA strains from various wards of our teaching hospital located in Kuala Lumpur, the capital city of Malaysia, and performed antimicrobial susceptibility testing on these strains. The strains were then molecularly characterized via staphylococcal cassette chromosome (SCC) mec and virulence gene (cna, sea, seb, sec, sed, see, seg, seh, sei, eta, etb, Panton-Valentine leukocidin and toxic shock syndrome toxin-1) typing; a subset of 49 strains isolated from the intensive care unit was also typed using PFGE. Most strains were found to be resistant to ciprofloxacin (92.5 %), erythromycin (93.4 %) and gentamicin (86.8 %). The majority (72.0 %) of strains were found to harbour SCCmec type III-SCCmercury with the presence of ccrC, and carried the sea+cna gene combination (49.3 %), with cna as the most prevalent virulence gene (94.0 %) detected. We identified four PFGE clusters, with pulsotype C (n=19) as the dominant example in the intensive care unit, where this pulsotype was found to be associated with carriage of SCCmec type III and the sea gene (P=0.05 and P=0.02, respectively). In summary, the dominant MRSA circulating in our hospital in 2009 was a clone that was ciprofloxacin, erythromycin and gentamicin resistant, carried SCCmec type III-SCCmercury with ccrC and also harboured the sea+cna virulence genes. This clone also appears to be the dominant MRSA circulating in major hospitals in Kuala Lumpur.
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http://dx.doi.org/10.1099/jmm.0.000387DOI Listing
December 2016

CD64 and Group II Secretory Phospholipase A2 (sPLA2-IIA) as Biomarkers for Distinguishing Adult Sepsis and Bacterial Infections in the Emergency Department.

PLoS One 2016 22;11(3):e0152065. Epub 2016 Mar 22.

Department of Biochemistry, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.

Introduction: Early diagnosis of sepsis and bacterial infection is imperative as treatment relies on early antibiotic administration. There is a need to develop new biomarkers to detect patients with sepsis and bacterial infection as early as possible, thereby enabling prompt antibiotic treatment and improving the survival rate.

Methods: Fifty-one adult patients with suspected bacterial sepsis on admission to the Emergency Department (ED) of a teaching hospital were included into the study. All relevant cultures and serology tests were performed. Serum levels for Group II Secretory Phospholipase A2 (sPLA2-IIA) and CD64 were subsequently analyzed.

Results And Discussion: Sepsis was confirmed in 42 patients from a total of 51 recruited subjects. Twenty-one patients had culture-confirmed bacterial infections. Both biomarkers were shown to be good in distinguishing sepsis from non-sepsis groups. CD64 and sPLA2-IIA also demonstrated a strong correlation with early sepsis diagnosis in adults. The area under the curve (AUC) of both Receiver Operating Characteristic curves showed that sPLA2-IIA was better than CD64 (AUC = 0.93, 95% confidence interval (CI) = 0.83-0.97 and AUC = 0.88, 95% CI = 0.82-0.99, respectively). The optimum cutoff value was 2.13μg/l for sPLA2-IIA (sensitivity = 91%, specificity = 78%) and 45 antigen bound cell (abc) for CD64 (sensitivity = 81%, specificity = 89%). In diagnosing bacterial infections, sPLA2-IIA showed superiority over CD64 (AUC = 0.97, 95% CI = 0.85-0.96, and AUC = 0.95, 95% CI = 0.93-1.00, respectively). The optimum cutoff value for bacterial infection was 5.63μg/l for sPLA2-IIA (sensitivity = 94%, specificity = 94%) and 46abc for CD64 (sensitivity = 94%, specificity = 83%).

Conclusions: sPLA2-IIA showed superior performance in sepsis and bacterial infection diagnosis compared to CD64. sPLA2-IIA appears to be an excellent biomarker for sepsis screening and for diagnosing bacterial infections, whereas CD64 could be used for screening bacterial infections. Both biomarkers either alone or in combination with other markers may assist in decision making for early antimicrobial administration. We recommend incorporating sPLA2-IIA and CD64 into the diagnostic algorithm of sepsis in ED.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0152065PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4803226PMC
August 2016

Bitten by the "flying" tree snake, Chrysopelea paradisi.

J Emerg Med 2012 Apr 10;42(4):420-3. Epub 2011 Dec 10.

Department of Emergency Medicine, Universiti Kebangsaan Malaysia Medical Centre, Jalan Ya'acob Latiff, Bandar Tun Razak, Cheras, Kuala Lumpur, Malaysia.

Background: The paradise tree snake, Chrysopelea paradisi, is a rear-fanged colubrid. Like other members of the genus Chrysopelea, it is able to glide through the air, and thus, is commonly known as a "flying snake." There are few documented effects of its bite on humans.

Case Report: A 16-year-old military college student presented to the Emergency Department (ED) of an urban teaching hospital 2 h after being bitten by C. paradisi. There were multiple bite marks and the patient reported moderate pain on the left index finger. There was no evidence of significant local or systemic envenomation. A transient prolonged coagulation profile and raised creatine kinase level were noted.

Conclusion: The full effects of a bite from C. paradisi remain uncharacterized. This case featured only mild local effect. After the administration of first aid, non-sedating analgesia, anti-tetanus toxoid injection, and broad-spectrum antibiotic coverage, a short stay in the ED observation ward with regular monitoring of vital signs and serial wound inspection are recommended. More effort is required to increase awareness of the prevention and management of snakebite with equal emphasis on conservation of wildlife and their natural habitat.
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http://dx.doi.org/10.1016/j.jemermed.2011.03.038DOI Listing
April 2012