Comparing the Accuracy Rate of Two Different Universal Primers in Enteric Pathogen Diagnosis in Blood

Background: Detecting enteric bacteria in blood by culture is a slow assay with low accuracy rate. PCR might be a suitable alternative assay but as several species can cause bacteremia, it is necessary to use universal primers. Objectives: In this study we evaluated and compared two pairs of universal primers in detecting four enteric bacteria in blood, which are common causes of bacteremia in human. Materials and Methods: Standard strains of E. faecalis, S. typhi, E. coli, and S. Aeruginosa, were used in this study. A serially diluted bacterial suspension of all strains was made for inoculation to four sets of defibrinated sheep blood which were used to prepare blood specimens with different bacterial contents for performing routine assay and PCR. PCR was performed using two different universal primers designed from two ribosomal genes, 16sr RNA and 23sr RNA. Results: PCR with 16sr RNA universal primer showed more accuracy rate than both blood culture and PCR with 23sr RNA universal primer. Mean time for performing PCR assay and blood culture was eight and 48 hours, respectively. Conclusions: Both PCR with 16sr RNA and 23sr RNA universal primers have more accuracy rate than blood culture and are faster in detection of bacteremia. PCR with 16sr RNA universal primer is more accurate than both PCR with 16sr RNA universal primer and blood culture for diagnosis of bacteremia.