Detection of Salmonella typhi by nested polymerase chain reaction in blood, urine, and stool samples.

A nested polymerase chain reaction (PCR) specific for Salmonella enterica serovar Typhi was used for the detection of the pathogen in blood, urine, and stool samples from 131 patients with clinical suspicion of typhoid fever. The sensitivity of blood culture, the PCRs with blood, urine, and feces, and the Widal test were 61.8%, 84.5%, 69.3%, 46.9%, and 39.0%, respectively. The sensitivity of the PCRs with blood (P < 0.001) and urine (P = 0.01) were significantly higher, and the sensitivity of the PCR with feces (P > 0.05) was similar to that of blood culture. Combined, the PCRs on urine and feces showed positive results for 16 (70%) of 23 typhoid patients with negative results with blood culture and PCR with blood. These results show that the PCR with blood is a sensitive method for the diagnosis of typhoid fever, and that the PCRs with urine and feces could be useful complementary tests.