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. 2011 Nov;5(6):398-403.
doi: 10.1111/j.1750-2659.2011.00244.x. Epub 2011 Mar 30.

Role of procalcitonin and C-reactive protein in differentiation of mixed bacterial infection from 2009 H1N1 viral pneumonia

Shin Ahn  1 , Won Young Kim, Sung-Han Kim, SangBum Hong, Chae-Man Lim, YounSuck Koh, Kyung Soo Lim, Won Kim
Affiliations

Role of procalcitonin and C-reactive protein in differentiation of mixed bacterial infection from 2009 H1N1 viral pneumonia

Shin Ahn et al. Influenza Other Respir Viruses. 2011 Nov.

Abstract

Background: Mixed bacterial infection is an important contributor to morbidity and mortality during influenza pandemics. We evaluated procalcitonin (PCT) and C-reactive protein (CRP) in differentiating pneumonia caused by mixed bacterial and 2009 H1N1 influenza infection from 2009 H1N1 influenza infection alone.

Methods: Data were collected retrospectively over a 7-month period during the 2009 H1N1 influenza pandemic. Patients visiting emergency department and diagnosed as community-acquired pneumonia caused by 2009 H1N1 infection were included (n = 60).

Results: Mixed bacterial and viral infection pneumonia (n = 16) had significantly higher PCT and CRP levels than pneumonia caused by 2009 H1N1 influenza alone (n = 44, P = 0·019, 0·022 respectively). The sensitivity and specificity for detection of mixed bacterial infection pneumonia was 56% and 84% for PCT > 1·5 ng/ml, and 69% and 63% for CRP > 10 mg/dl. Using PCT and CRP in combination, the sensitivity and specificity were 50% and 93%, respectively.

Conclusion: Procalcitonin and CRP alone and their combination had a moderate ability to detect pneumonia of mixed bacterial infection during the 2009 H1N1 pandemic. Considering high specificity, combination of low CRP and PCT result may suggest that pneumonia is unlikely to be caused by mixed bacterial infection.

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Figures

Figure 1
Figure 1
Receiver‐operating characteristics curve for discriminating between 2009 H1N1 pneumonia and mixed infection pneumonia for procalcitonin and C‐reactive protein (CRP) on initial emergency department visit [Area under curve 0·698 (95% confidence interval 0·523–0·873) for procalcitonin, 0·696 (95% confidence interval 0·539–0·852) for CRP].
Figure 2
Figure 2
Box plot of procalcitonin and C‐reactive protein levels on initial emergency department visit between 2009 H1N1 pneumonia and mixed infection pneumonia. ○: minor outliers; *: extreme outliers.
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