Detection of Typhoidal and ParatyphoidalSalmonellain Blood by Real-time Polymerase Chain Reaction

Abstract

Based on lessons learned, we recommend that future field trials of this and other novel diagnostics that detect typhoidal and nontyphoidal Salmonella employ multiple methodologies to define a "positive" sample.

Clinical Significance of Molecular Diagnostic Tools for Bacterial Bloodstream Infections: A Systematic Review

“…Liesenfeld et al, 2014, added that the PCR technique seems to be superior to BC given its accuracy of detecting bacteria and fungi [12]. Tennant et al, 2015, investigated the development of quantitative PCR (q-PCR) and its application in detecting Salmonella species [13]. Jordana-Lluch et al, 2015, revealed the sensitivity improvement and clinical accuracy of PCR [14].…”

“…Some reviewed publications reported on BC as a good technique in diagnosis of bBSI but also presented its various disadvantages such as long turnaround time, easy contamination, and false negative and positive results [8, 13, 15–17, 19]. A total of 12 out of 18 reviewed papers explored the BC's performance and recommended different and improved molecular techniques to detect BSIs with a particular emphasis on bacteria.…”

“…However, when q-PCR positive specimens were considered to be true positives, blood culture only exhibited 28.57% sensitivity and a specificity of ≥90% for all comparisons. The q-PCR was significantly faster than blood culture in terms of detection of typhoid and paratyphoid infections [13]. …”

“…To overcome this challenge, molecular technique has to be used for rapid screening of bacteria. Tennant et al, 2015, investigated the use of gold standard method for diagnosis of enteric fever caused by Salmonella typhi or Salmonella paratyphi A or B in bone marrow culture [13]. However, because bone marrow aspiration is highly invasive, many hospitals and large health centers perform blood culture instead.…”

“…In this study, excluding results attributable to contaminants, SeptiFast showed a sensitivity of 85.0% and a specificity of 93.5% compared to blood culture; and the rate of positive results was significantly higher with SeptiFast, 14.6%, than blood culture, 10.3% [12]. In a related study conducted in Pakistan, real-time PCR was significantly faster at detecting and identifying Salmonella typhi or Salmonella paratyphi A than classical microbiological techniques; though this technique is more sensitive it has missed some microbes detected by BC [13]. PCR of bacterial DNA seems to be the most sensitive molecular technique nowadays; even though more has to be done to improve its sensitivity, PCR stands to be the future direction tool in bBSI diagnosis.…”