Detection of Salmonella typhi by polymerase chain reaction: Implications in diagnosis of typhoid fever

The present study was conducted to detect Salmonella typhi by polymerase chain reaction (PCR) in a clinical setting. A group of 40 clinically suspected cases of typhoid fever, lasting for about 3-11 days, with or without chills and rigors and hepatosplenomegaly were selected. Of these, 20 were culture positive and the remaining 20 were found to be negative by conventional blood culture technique. Primary PCR was followed by nested PCR using two sets of primers corresponding to flagellar gene of S. typhi strain. Two bands of about 458 and 343 bp were detected in 20 blood culture positive cases and 12 of the 20 culture negative ones. In the simulated group of samples, no amplification was detected. Our results suggest that PCR-based diagnosis is particularly useful for all clinically suspected cases of typhoid fever. The sensitivity of PCR and its potential use in routine diagnosis and epidemiological studies of typhoid fever can be exploited to complement studies by including bone marrow culture, faeces and bile samples