Methods: Patients presenting with LRTI were prospectively enrolled in 16 primary care networks in 11 European countries. Blood, sputum and NP flocked swabs, CRP and PCT were obtained at presentation and CXR was obtained within 7 days. Microbiological etiology was obtained using bacterial culture, PCR and serology, as appropriate.
Results: Microbiological, CRP and/or PCT results were available for 1832 subjects (84 with radiographically-proven CAP). 8 respiratory viruses and 5 bacterial pathogens were recovered. 38 (48%), 11 (14%), 31(39%) of CAP subjects had CRP <20, 20-50, >50mg/L, respectively. 88% of CAP subjects had PCT <0.5 μg/L. Most non-CAP subjects had low biomarker values with CRP <20 mg/L (75%) and PCT <0.1 μg/L (92%). Mixed infection were the most common etiology for CAP subjects with CRP <20 mg/L (21%) and >50 mg/L (48%) followed by H. influenzae (13%) and rhinovirus (13%), respectively. Mixed infection was also the most common finding in CAP subjects with PCT <0.5 μg/L (23-50%); for those with PCT ≥0.5μg/L, rhinovirus was most common (66.6%). Influenza was not recovered in CAP subjects with CRP >50m/L or PCT >0.5 μg/L. Subjects with CRP 20-50mg/L (16.4%) and those with PCT 0.25-0.5 μg/L (28.6%) had the greatest proportion of influenza cases. In those with PCT ≥0.5 μg/L, rhinovirus was most common.
Conclusion: Mixed infections were the most common finding across biomarker concentrations. Most influenza cases did not occur in subjects with the highest biomarker levels, regardless of whether they had CAP. Further elucidation of the role of mixed infection in primary care patients with LRTI and the utility of biomarkers to differentiate between respiratory viruses in these patients is needed.
C. Lammens, None
S. Coenen, None
C. Butler, None
P. Little, None
T. Verheij, None
H. Goossens, None