Abstract
Background: Though several reports of the resistance to first-choice antimicrobial for enteric fever i.e. Ceftriaxone emerge, empirical use of the same antimicrobial without diagnostic confirmation continues. The gold standard, blood culture has poor sensitivity and lacks rapidity. Culturing bone marrow though definitive, is invasive. It is mostly used as last resort to solving undifferentiated fever cases. Serology cannot be used to expand its scope to give information on antimicrobial resistance. This leads us to molecular diagnosis as alternative. Hence, this study was aimed to evaluate performance of the multiplex Real-time PCR using novel targets for early diagnosis of enteric fever on blood clot samples at a tertiary care center. Materials and Methods: In this retrospective non-randomized study, 116 patients with diagnosis of enteric fever were included and the DNA extracted from blood clot samples collected for routine WIDAL test were subjected to multiplex Real-time PCR assay targeting novel sequences of Salmonella ser. Typhi and Salmonella ser. Paratyphi A. The results of the new assay were compared to simultaneously requested blood culture, WIDAL tube agglutination tests and or final clinical impression. Results: The multiplex Real-time PCR assay using DNA extracted from clot sample gave an accuracy of 70.7% with an overall sensitivity of 50.9% and specificity of 82.1% against all 116 enteric fever cases with positive predictive value of 92.2% and negative predictive value of 28.8%. The performance of this PCR was statistically significant (p = 0.001) in 116 patients with diagnosis of enteric fever either by laboratory tests or clinically confirmed cases. Conclusion: To diagnose enteric fever using this test, further optimization is needed to improve the sensitivity by enrichment of clot samples and screening of additional sequences with a better detection limit could help to improve the overall performance of this diagnostic test.
Published Version
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