976. Procalcitonin as an Indicator of Bacterial Infection in Seasonal and Pandemic Influenza
Session: Poster Abstract Session: Clinical Studies of Bacterial Infection
Saturday, October 22, 2011
Room: Poster Hall B1
Background: Respiratory tract infections (RTI) are a frequent cause of hospitalization during the influenza season. Currently there exist no reliable indicators to distinguish between viral and bacterial causes, nor to predict who may develop secondary bacterial infection. Procalcitonin (PCT) is a 114 amino acid precursor converted into calcitonin in thryroid C-cells, and undetectable in healthy patients (pts). Released 2-3 hours (h) after bacterial infection, it peaks at 6-8h and remains elevated for 24h. It is attenuated by cytokines released by viral infection, and has been shown to be a good predictor of viral versus bacterial infection. The purpose of this study was (1) to determine if PCT can distinguish bacterial versus viral causes of RTI in Influenza pts and (2) to predict bacterial infection with concomitant influenza.

Methods: We prospectively followed serum PCT (miniVidas, BioMerieux, Durham, NC) on pts with Influenza A+ rapid TruFlu® (Meridian Bioscience Inc, Cincinnati, OH) on hospital day 0, 2, 5, and 7 using an enzyme linked fluorescent immunoassay. Charts were reviewed for epidemiologic data. On-line statistical predictive value calculator was used to determine test characteristics. PCT was stratified into low (<0.25 ng/mL) and high (>0.25 ng/mL) values.

Results: Of 34 pts tested during 2010-11 influenza season, 29 (85.3%) had negative (<0.05) or low (>0.05 - <0.25) PCTs on day 0. Five pts had high PCTs. Initial Chest XRays (CXR) were done on 29 pts. 1 showed an infiltrate on day 0, and another pt on day 2. Of pts with a high admission PCT, only 1/5 had an infiltrate on CXR. Eight pts had serial PCTs: 4 remained level, 3 markedly increased (from <0.05 to high) and 1 decreased. Test characteristics revealed a sensitivity of 33.3%, specificity of 87.1%, and a negative predictive value of 93.1%.

Conclusion: Our results indicate that PCT, with a good specificity and negative predictive value may be useful in ruling out bacterial infection, either a concomitant pneumonia or secondary sepsis in influenza pts. Additionally, trending PCT may be a useful marker of progression or resolution of bacterial illness, and warrants larger scale evaluation.

Subject Category: D. Diagnostic microbiology

Marnie Rosenthal, DO, MPH, Internal Medicine/Infectious Diseases, Jersey Shore University Medical Center, Neptune, NJ, Andreea Nagy, Jersey Shore University Medical Center, Neptune, NJ and Albert Rojtman, MD, Microbiology, Jersey Shore University Medical Center, Neptune, NJ


M. Rosenthal, BioMerieux: Product Support, Reseach Assay and Study Reagent

A. Nagy, None

A. Rojtman, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.