Early Diagnosis of Typhoid By PCR For FliC-d Gene of Salmonella Typhi in Patients Taking Antibiotics.

OBJECTIVE: To compare PCR (Polymerase Chain Reaction) with blood culture, typhi-dot and Widal test for the diagnosis of typhoid in patients taking antibiotics. STUDY DESIGN: Cross-sectional, comparative study. PLACE AND DURATION OF STUDY: National University of Sciences and Technology, Islamabad, Pakistan, from April 2013 to August 2014. METHODOLOGY: One hundred and five patients were included in the study. Blood was collected and inoculated into tryptone soya broth for culture. Any growth obtained was identified by API 20 E and confirmed by Salmonella anti-sera. Typhi-dot and Widal test were also done on all the samples. DNA extraction was done and PCR was carried out. RESULTS: Among the 105 patients, 79 (75.2%) were males and 26 (24.8%) were females, with mean age of 20.64 ±14 years. Typhi-dot was positive in 58 (55.2%) and negative in 47 (44.8%) patients. Blood widal test was positive in 27 (25.7%) and negative in 78 (74.3%) patients. Salmonella Typhi was positive on blood culture in only one (1%) patient. PCR for Salmonella Typhi was positive in 102 (97.1%) and negative in 3 (2.9%) patients. Positive cases detected by PCR were significantly higher as compared to Typhi-dot (p < 0.001), blood Widal test (p < 0.001) and blood culture (p < 0.001). CONCLUSION: Positivity rate of PCR was significantly higher as compared to blood culture, Typhi-dot or Widal test for diagnosing typhoid in patients who were already taking antibiotics.