Prospective Comparison of Eubacterial PCR and Measurement of Procalcitonin Levels with Blood Culture for Diagnosing Septicemia in Intensive Care Unit Patients

Rapid identification of infection has a major impact on the clinical course, management, and outcome of critically ill intensive care unit (ICU) patients. We compared the results of PCR and procalcitonin with blood culture for ICU patients suspected of having septicemia. Ninety patients (60 patients meeting the criteria for sepsis and 30 patients not meeting the criteria for sepsis) were evaluated. Compared with blood culture as the gold standard, the sensitivity, specificity, and positive and negative predictive values for PCR were 100%, 43.33%, 46.87%, and 100%, respectively, and for procalcitonin were 100%, 61.66%, 56.6%, and 100%, respectively. The average times required to produce a final result were as follows: PCR, 10 h; blood culture, 33 h; procalcitonin, 45 min. Both PCR and procalcitonin may be useful as rapid tests for detecting septicemia but compared with blood cultures lacked specificity.A rapid and reliable system to detect bacteria in the bloodstream would be clinically useful as it could guide early appropriate antibiotic treatment and result in improved patient survival (14). The gold standard for the diagnosis of infection is the isolation and identification of organisms by culture (27). This process usually requires 24 h or more. A large proportion of patients suspected of having septicemia have negative blood cultures (3) due to either previous antibiotic treatment, samples of small volume, transient bacteremias, or sepsis of nonbacterial origin (8, 30). Given the slowness and low sensitivity of blood culture, there is a need for more-rapid and more-sensitive techniques. PCR, which amplifies characteristic genes of microorganisms, is one such technique. In clinical conditions with diverse etiological agents in sterile sites, e.g., blood in sepsis, a broad-range bacterial PCR which uses a primer pair aimed at highly conserved DNA coding regions on bacterial rRNA can be used (8, 10, 11, 20). This is described as eubacterial PCR as well as broad-range bacterial PCR as it detects an rRNA gene component present in all bacteria. PCR cannot differentiate DNA sequences from viable and nonviable bacteria. The value of this test may be enhanced if it is coupled with a host response biomarker indicative of infection and systemic inflammation. Procalcitonin is one such marker and is gaining increasing importance in identification of sepsis (1, 15, 16). Procalcitonin levels are undetectable in healthy individuals but increase in patients with bacterial sepsis and correlate well with the severity of the illness (5, 19, 29).The aim of this study was to compare the results for eubacterial PCR and procalcitonin with blood culture in intensive care unit (ICU) patients suspected of having septicemia.