1.Detection of enteroviruses during a 2018 hand, foot and mouth disease outbreak in Malaysia
Lee, M.H.P. ; Chong, Y.M. ; Tay, C.G. ; Koh, M.T. ; Chem, Y.K. ; Noordin, N. ; Jahis, R. ; Sam, I.C. ; Chan, Y.F.
Tropical Biomedicine 2021;38(No.1):150-153
Hand, foot, and mouth disease (HFMD) is a common childhood disease caused by
enteroviruses. In 2018, a HFMD outbreak in Malaysia affected over 76,000 children. In this
study, we used RT-qPCR and CODEHOP PCR to detect the causative agents in 89 clinically
diagnosed HFMD patients in Kuala Lumpur and Selangor. Most (62.9%) of the children were
below 3 years old. PCR with either assay detected enteroviruses in 84.2% (75/89) and CODEHOP
PCR successfully typed 66.7% (50/75) of the enteroviruses. Sequencing of CODEHOP amplicons
showed co-circulation of multiple enteroviruses with coxsackievirus A6 (CV-A6) and A16 as
the predominant serotypes, but not the neurovirulent enterovirus A71. CV-A6 infection was
more common in children less than 12 months old (p=0.01) and was more likely to cause
vesicles in the gluteal area (p=0.01) compared to other enteroviruses. Establishing a robust
identification method during HFMD outbreaks is important for patient management and
public health responses.
2.Molecular detection of Salmonella enterica serovar Typhi by Vi-qPCR
Nik Noorul Shakira Mohamed Shakrin ; Siti Noor Adnalizawati Adnan ; Asmah Hani Abdul Wahab ; R. Pusparani Ramasamy ; Wan Noraini Wan Yussof ; Noorliza Noordin ; Khebir Verashahib ; Rohani Jahis
Malaysian Journal of Microbiology 2018;14(6):483-489
Aims:
To develop a real-time polymerase chain reaction system Vi-qPCR in the detection of Salmonella enterica serovar Typhi (S. Typhi), targeting the vexC gene encoding for Vi antigen (capsular polysaccharide antigen) and to evaluate its sensitivity and specificity performance using pure cultures of S. Typhi and other enteric pathogens.
Methodology and results:
Microbiological, biochemical and serotyping tests were conducted to determine the phenotypic characteristics of S. Typhi and other enteric pathogens in our collection. Primers were designed using Primer3 software and their in-silico specificity were analysed using Basic Local Alignment System Tool (BLAST). Optimisation of PCR annealing temperature was done prior to assessment of sensitivity and specificity performance against artificial serially diluted seeded stools. The primers were found to be 100% specific in the detection of S. Typhi towards 32 tested clinical strains. Verification of gene amplification by comparing the nucleotide sequences against reference genes in the GenBank database revealed high specificity to S. Typhi. Statistical analysis indicates that this method results in 100% sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). Moreover, Vi-qPCR allows the detection of S. Typhi as low as 131.4 CFU/g of stool sample.
Conclusion, significance and impact of study
A rapid and sensitive method for detection of Salmonella enterica serovar Typhi (S. Typhi) is desired as a diagnostic tool to improve typhoid management. The Vi-qPCR represent a promising non-invasive diagnostic tool for medical microbiology laboratories as a method for the detection of S. Typhi in both pure culture and stool specimens especially in chronic asymptomatic carriers where shedding of S. Typhi is intermittent and sometimes occurs in low level.