Real-time PCR as a Diagnostic Tool for Bacterial Diseases

Max Maurin


Expert Rev Mol Diagn. 2012;12(7):731-754. 

In This Article

Quantification of Bacterial Load Using qPCR

qPCR tests can be used to quantify the bacterial load in clinical samples. Because these tests quantify DNA from both viable and nonviable bacteria, results may be higher than those obtained by quantitative culture. A high correlation between both methods was reported for S. pneumoniae.[25] Such a correlation should be assessed for each clinical situation. qPCR tests allow quantification of fastidious and noncultivable microorganisms. In-house qPCR tests have been used for quantification of the bacterial load in clinical samples to differentiate infection from commensalism,[25] to determine disease severity and patients' prognosis[147,257–260] and to evaluate treatment efficacy.[261–264] A high bacterial load in clinical samples may correlate with true infection versus commensalism, high severity and poor outcome. The absence of reduction of bacterial load in a patient receiving antibiotics may indicate treatment failure, particularly due to acquired antibiotic resistances. Although these tests are not currently used on a routine basis, published data indicate that determination of the bacterial load in clinical samples using qPCR potentially represents a useful marker for evaluation of prognostic and treatment efficacy in patients with acute or chronic bacterial infections, as for many viral diseases.