Multiplex PCR for differential diagnosis of emerging typhoidal pathogens directly from blood samples

Abstract

SUMMARYClassicallySalmonella entericaserovar Typhi (S. Typhi) is associated with typhoid, a major health problem in developing countries. However, in recent yearsS. Paratyphi A and Vi-negative variants ofS. Typhi have emerged rapidly. We have developed a nested multiplex PCR targeting five different genes for differential diagnosis of typhoidal pathogens which has been optimized to be directly applicable on clinical blood samples. Of 42 multiplex PCR-positive blood samples, 26, nine, and two were Vi-positiveS. Typhi, Vi-negativeS. Typhi andS. Paratyphi A, respectively, and five patients were found to have mixed infection. Seventeen patients grewSalmonellafrom blood culture and the remaining 25 were positive in theSalmonella-specific PCR. Tests with several common pathogens confirmed the specificity of the assay. We conclude that the proposed multiplex PCR is rapid, sensitive and specific for the diagnosis of typhoidal pathogens directly from blood samples.