Annals of Clinical Microbiology, The official Journal of the Korean Society of Clinical Microbiology


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Indexed in KCI, KoreaMed, Synapse, DOAJ
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pISSN 2288-0585 eISSN 2288-6850

The Value of Serum Procalcitonin Level for Differentiation between Contaminants and Pathogens in Bacteremia

Original article

Annals of Clinical Microbiology (Ann Clin Microbiol) 2011 March, Volume 14, Issue 1, pages 7-12.

The Value of Serum Procalcitonin Level for Differentiation between Contaminants and Pathogens in Bacteremia

Hei Kyung Jin1, Jae Yun Jang1, Young Uh1, Ohgun Kwon1, Kap Jun Yoon1, Hyo Youl Kim2, Young Keun Kim2
Departments of 1Laboratory Medicine and 2Infectious Diseases, Yonsei University Wonju College of Medicine, Wonju, Korea


Background: Bacteremia is a life-threatening infection, and prognosis is highly dependent on early recognition and treatment with appropriate antimicrobial agents. We investigated the diagnostic performance of serum procalcitonin (PCT) for differentiation between contaminants and true pathogens in blood cultures. 

Methods: Serum PCT, C-reactive protein (CRP) and blood culture were performed for 473 patients between February 2008 and October 2008. We retrospectively reviewed the patients’ clinical characteristics and laboratory results based on medical records. 

Results: The mean concentration of PCT was significantly different between the two negative and positive blood culture groups (6.45 ng/mL vs 28.77 ng/ mL, P<0.001). Procalcitonin levels were found to be markedly higher in those with Gram-negative bacilli (mean±SD; 59.58±67.00 ng/mL) bacteremia than in those with Gram-positive cocci (mean±SD; 17.75±42.88 ng/mL) bacteremia (P<0.001). The areas under the receiver operating characteristic curves (95% confidence interval) for PCT and CRP were 0.880 (0.820∼ 0.940) and 0.637 (0.538∼0.736), respectively. The use of a PCT level of 2 ng/mL as a cutoff value yielded an 83.6% positive predictive value and a 77.4% negative predictive value for the detection of bacteremia pathogens. 

Conclusion: Serum PCT is a helpful diagnostic marker for rapidly and accurately distinguishing between contaminants and pathogens in blood cultures. (Korean J Clin Microbiol 2011;14:7-12)


Procalcitonin, Blood culture, Bacteremia, Contamination