Validation Of Polymerase Chain Reaction For Diagnosis Of Typhoid Fever In Egyptian Patients

Abstract

Background: Typhoid fever continues to be a major health problem in many parts of the
world, particularly the developing countries. The rate of typhoid fever is increasing in Egypt. Clinical
diagnosis of enteric fever is difficult, as the symptoms associated with enteric fever overlap with those
of other febrile illness. The objective of this study is to validate a PCR technique for the detection of
typhoid infection. So, we can differentiate between the true and current infections by this organism
from the falsely positive antibodies produced from previous or treated infections.
Methods: This study comprised 115 patients (88 males and 27 females) from different ages
experienced the clinical symptoms of typhoid fever. This study was carried out at Mansoura University
Hospitals. The blood samples collected were subjected to culture, Widal test and PCR targeting the hto
gene of S. Typhi.
Results: PCR standardized for hisJ (hto) gene result in specific amplicon of 495-bp. In
positive PCR cases of typhoid (total 15), a single band of 495bp corresponding to hisJ (hto) gene was
obtained. The PCR assay was found to be highly specific and the true positive typhoid cases (n = 9) are
positive of Widal test, blood culture and/or PCR. PCR was sensitive than blood culture for diagnosis of
typhoid fever.
Conclusion: We recommend using PCR as an alternative to blood culture for diagnosis of
typhoid fever. We also recommend performance of a large scale study to test this PCR technique for
screening for tyhoid fever in Egypt.