• Safiullah Khan Achakzai

• Zafar Ahmed

• Abdul Samad

• Muhammad Naeem

• Hamida

• Muhammad Ali

• Muhammad Rizwan

• Farah Sabeen Bugti

• Sania Ashraf

• Muhammad Tayyeb

• Olena Pokryshko

Abstract

Objective: The study aimed at investigating the validity of multiplex-PCR for S. typhi detection in blood specimens of Widal-positive typhoid patients and to compare the detection rate of PCR with blood culture. Methodology: Blood specimens were collected from 105 clinically suspected and Widal- positive typhoid patients. For the bacterial culture, the specimens were inoculated into Brain Heart Infusion (BHI) broth. The growth was subcultured on Xylose Lysine Deoxycholate (XLD) and Salmonella-Shigella (SS) agar. Obtained colonies were Gram-stained and subjected to biochemical tests. Multiplex-PCR was performed to amplify a 639-bp fragment of aroC gene specific for Salmonella and a 495-bp fragment of fliC gene for S. typhi. Results: Of 105 Widal-positive typhoid patients, 73 (69.6%) were positive by PCR for the presence of S. typhi and 24 (22.8%) by blood culture. PCR could also amplify S. typhi DNA from 49 (46.7%) culture-negative patients. Widal test with false-positive result was observed in 32 (30.4%) suspected cases. Conclusion: Our study suggests that PCR-based diagnosis of typhoid fever is distinctly useful in culture-negative cases and also false-positive cases as detected by Widal test.

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