Early detection of typhoid by polymerase chain reaction

Background: Typhoid is a common problem in developing countries. Cultivation of bacteria and serology (especially Widal test) give unacceptable levels of false-negative and false-positive results, respectively. Patients and Methods: In this study, a recently introduced polymerase chain reaction-based technique (which has 100% specificity for Salmonella typhi) was compared with blood culture and Widal test during the first week of illness of 82 suspected cases of typhoid. Results: The respective figures of positivity for PCR, blood culture and Widal test were 71.95%, 34.1%, and 36.5%. A control group of 20 healthy persons gave figures of 0%, 0%, and 33.3%, respectively. Conclusion: We conclude that this PCR-based technique is not only absolutely specific, but also very sensitive and, therefore, much superior to blood culture and Widal test for the early diagnosis of typhoid.