Use of Urine with Nested PCR Targeting the Flagellin Gene (fliC) for Diagnosis of Typhoid Fever

This study was planned to evaluate the efficacy of the use of nested PCR with a large volume of easily available urine as an effort to devise a test that can meet the levels necessary to be considered a gold standard for the diagnosis of typhoid fever. A total of 60 subjects with suspected cases of typhoid fever and 20 apparently healthy control subjects were included in the study. The study period extended from March 2010 to June 2011. Blood, urine, and stool specimens were collected from the participating individuals. Nested PCR was done targeting the flagellin gene (fliC) of Salmonella enterica subspecies enterica serotype Typhi. Specimens in all three categories could be collected from 22 of the subjects with suspected cases of typhoid fever; 21 of the 22 urine samples (95.4%) yielded a desired amplicon of 343 bp, whereas none of the urine samples collected from the 20 control subjects (0%) yielded the amplicon. The analyses of blood and stool samples were found to be inferior to urine sample analysis in sensitivity, with detection rates of 90.9% and 68.1%, respectively. Culture isolation was observed to display very poor sensitivity (31.8%). A large volume of urine may be the ideal specimen for PCR-based detection of typhoid fever.