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.