Dataset Information

Identification of Five Novel Salmonella Typhi-Specific Genes as Markers for Diagnosis of Typhoid Fever Using Single-Gene Target PCR Assays.

ABSTRACT: Salmonella Typhi (S. Typhi) causes typhoid fever which is a disease characterised by high mortality and morbidity worldwide. In order to curtail the transmission of this highly infectious disease, identification of new markers that can detect the pathogen is needed for development of sensitive and specific diagnostic tests. In this study, genomic comparison of S. Typhi with other enteric pathogens was performed, and 6 S. Typhi genes, that is, STY0201, STY0307, STY0322, STY0326, STY2020, and STY2021, were found to be specific in silico. Six PCR assays each targeting a unique gene were developed to test the specificity of these genes in vitro. The diagnostic sensitivities and specificities of each assay were determined using 39 S. Typhi, 62 non-Typhi Salmonella, and 10 non-Salmonella clinical isolates. The results showed that 5 of these genes, that is, STY0307, STY0322, STY0326, STY2020, and STY2021, demonstrated 100% sensitivity (39/39) and 100% specificity (0/72). The detection limit of the 5 PCR assays was 32?pg for STY0322, 6.4?pg for STY0326, STY2020, and STY2021, and 1.28?pg for STY0307. In conclusion, 5 PCR assays using STY0307, STY0322, STY0326, STY2020, and STY2021 were developed and found to be highly specific at single-gene target resolution for diagnosis of typhoid fever.

SUBMITTER: Goay YX

PROVIDER: S-EPMC5126401 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature

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Identification of Five Novel Salmonella Typhi-Specific Genes as Markers for Diagnosis of Typhoid Fever Using Single-Gene Target PCR Assays.

Goay Yuan Xin YX Chin Kai Ling KL Tan Clarissa Ling Ling CL Yeoh Chiann Ying CY Ja'afar Ja'afar Nuhu JN Zaidah Abdul Rahman AR Chinni Suresh Venkata SV Phua Kia Kien KK

BioMed research international 20161115

Salmonella Typhi (S. Typhi) causes typhoid fever which is a disease characterised by high mortality and morbidity worldwide. In order to curtail the transmission of this highly infectious disease, identification of new markers that can detect the pathogen is needed for development of sensitive and specific diagnostic tests. In this study, genomic comparison of S. Typhi with other enteric pathogens was performed, and 6 S. Typhi genes, that is, STY0201, STY0307, STY0322 ...[more]

PMID: 27975062

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Project description:Typhoid cases need to be diagnosed accurately for early antibiotic therapy and reducing mortality. Identification of Salmonella Typhi (S. Typhi) in blood culture is conclusive, but has poor sensitivity. Detection of S. Typhi by PCR from blood sample has shown promise. Real-time quantitative PCR (Q-PCR) has been widely used in diagnostics for its rapidity and reliability. In the present study, the performance of molecular methods like conventional PCR (C-PCR), nested PCR (N-PCR) and Q-PCR were investigated and compared by targeting S. Typhi specific flagellar fliC-d gene directly in blood samples for typhoid diagnosis.Analytical sensitivities and specificities of the PCR assays were determined under laboratory condition followed by diagnostic performances were demonstrated in 110 clinically diagnosed typhoid fever (CDTF) cases included as study subjects. The DNA detection limit of C-PCR was observed 3?×?10(4) copies/reaction; those of N-PCR and Q-PCR (cutoff Ct value, ?37) were 3 copies/reaction. The C-PCR was not further evaluated since it showed negative results with all clinical samples due to low sensitivity. Low isolation rate (21.8 %, 24/110) of S. Typhi by blood culture did not reflect the true burden of typhoid fever among the study subjects. Hence diagnostic performances of N-PCR and Q-PCR were determined considering CDTF cases positive by any of the diagnostic assay methods (n?=?81) as true positives. Laboratory confirmed non-typhoidal cases (n?=?29) were included as true negatives. On comparison, although both the assays were 100 % specific; sensitivity (91.4 % vs. 81.5 %) and efficiency (93.6 % vs. 86.4 %) of Q-PCR were better, but statistically not significant (p?>?0.1) than N-PCR. The positive and negative likelihood ratios of Q-PCR were ? and 0.09 which indicated the potential clinical utility of Q-PCR for typhoid diagnosis. Q-PCR was more rapid than N-PCR (2 h vs. 6 h) in obtaining test results.This study demonstrates for the first time that TaqMan-based Q-PCR assay performs more favorably than N-PCR for direct detection of S. Typhi DNA in blood samples. Direct and quantitative blood Q-PCR is a rapid and reliable method for diagnosis of typhoid fever.

Dataset Information

Identification of Five Novel Salmonella Typhi-Specific Genes as Markers for Diagnosis of Typhoid Fever Using Single-Gene Target PCR Assays.

Publications

Identification of Five Novel <i>Salmonella</i> Typhi-Specific Genes as Markers for Diagnosis of Typhoid Fever Using Single-Gene Target PCR Assays.

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