%0 Journal Article
%T CRP under 130 mg/L rules out the diagnosis of Legionella pneumophila serogroup 1 (URINELLA Study).
%A Klopfenstein T
%A Zayet S
%A Poloni S
%A Gendrin V
%A Fournier D
%A Vuillemenot JB
%A Selles P
%A Dussaucy A
%A Coureau G
%A Avalos-Fernandez M
%A Toko L
%A Royer PY
%A Lavoignet CE
%A Amari B
%A Puyraveau M
%A Chirouze C
%J Eur J Clin Microbiol Infect Dis
%V 43
%N 6
%D 2024 Jun 26
%M 38530466
%F 5.103
%R 10.1007/s10096-024-04814-x
%X <B>BACKGROUND: </B>In case of pneumonia, some biological findings are suggestive for Legionnaire's disease (LD) including C-reactive protein (CRP). A low level of CRP is predictive for negative Legionella Urinary-Antigen-Test (L-UAT).<BR><B>METHODS: </B>Observational retrospective study in Nord-Franche-Comté Hospital with external validation in Besançon University Hospital, France which included all adults with L-UAT performed during January 2018 to December 2022. The objective was to determine CRP optimal threshold to predict a L-UAT negative result.<BR><B>RESULTS: </B>URINELLA included 5051 patients (83 with positive L-UAT). CRP optimal threshold was 131.9 mg/L, with a negative predictive value (NPV) at 100%, sensitivity at 100% and specificity at 58.0%. The AUC of the ROC-Curve was at 88.7% (95% CI, 86.3-91.1). External validation in Besançon Hospital patients showed an AUC at 89.8% (95% CI, 85.5-94.1) and NPV, sensitivity and specificity was respectively 99.9%, 97.6% and 59.1% for a CRP threshold at 131.9 mg/L; after exclusion of immunosuppressed patients, index sensitivity and NPV reached also 100%.<BR><B>CONCLUSIONS: </B>In case of pneumonia suspicion with a CRP level under 130 mg/L (independently of the severity) L-UAT is useless in immunocompetent patients with a NPV at 100%. We must remain cautious in patients with symptoms onset less than 48 h before CRP dosage.