Early and Rapid Detection of Typhoid Fever by Nested PCR in Blood

Typhoid fever caused by Salmonella typhi is one of the major health problems in developing countries including Bangladesh. Still now blood culture is gold standard method for diagnosing typhoid fever, but this method is laborious, requires several days and detection rate is low. Failure of early laboratory diagnosis often leads to increased morbidity and mortality. This study was intended to apply a nested PCR in blood for early diagnosis of typhoid fever. In this cross sectional study blood samples were collected from 200 suspected typhoid fever patients attending Mymensingh Medical College Hospital, Bangladesh. Nested Polymerase Chain Reaction (n PCR) of flagellin gene was done in all the blood samples. At the same time all blood samples were subjected to culture by lytic centrifugation method. Culture positive isolates were identified as S. typhi by biochemical tests. Among the 200 blood samples, 57 (28.5%) were positive for S. typhi on nested PCR where as blood culture was positive for S. typhi in 16 (8%) samples. Among the 57 PCR positive samples, only 15 (26.3%) samples were culture positive for S. typhi and rest 42 (73.7%) were culture negative. So, in culture negative cases PCR can be used as a rapid diagnostic test for diagnosing typhoid fever. Considering time requirement, PCR takes one day, whereas blood culture takes 3 or more days to confirm diagnosis.