INTRODUCTION

1. INTRODUCTION RESULTS Objectives: The microbial etiology and especially the role of viruses in adult lower respiratory tract infections (LRTI) in the community is not well known. We therefore investigated the viral etiology in LRTI at the GP’s office in the European GRACE primary care network (PCN) using sensitive real-time PCR (RT-PCR). TABLE I. Most viruses were present at significantly higher rates in V1 samples when compared to V0 and V2. Boca, WU and KI presentation rates however, did not differ between V0, V1 and V2. This finding, added to the extremely low number of samples positive for these viruses raises doubt to their qualification as respiratory pathogens. TABLE II. DNA viruses presented with significantly lower viral loads (average CT 37) when compared to RNA viruses (average CT 30; CT 27 for INF B and the various COR’s). Significant differences between patients, versus controls and follow up samples, were detected for RSV, COR (as a group), COR OC43, PIV1, PIV3 and HRV. TABLE III. PIV – in particular PIV3 and PIV4 - positive patients were most prone to a positive follow up. For PIV3, significant associations were detected with Cor 229E (P value = 0.03) and Cor OC43 (P = 0.004) as secundary pathogens. Also INF A, PIV4, HRV and hMPV are frequently followed by secundary viral infections. All other combinations (empty cells in Table III, as well as non-depicted combinations) did not shown any association. KI and ADE are significantly the most persistent (found in the same patient within a 4-week interval) viruses (P = 0.017 and 0.009, resp.). Double infections (not shown). Despite the fact that DNA viruses are detected substantially in respiratory specimen, their overall impact is overestimated since these viruses are largely present in V0 samples, V1-double infections, or V2 samples. WU (26.7%) and KI (21.8%) were most frequently involved in double infections. Of all positive V1 patients, 6.4% was double-infected, in V0 and V2 double infections reached 7.3 and 6.5%, resp. MATERIALS & METHODS Figure 1. Primary Care Networks in GRACE. Patients: From October 2007 through May 2010, a total of 3,018 adult patients (V1) with LRTI in the community were enrolled in a prospective study in 14 PCNs in 12 European countries (Figure 1). Samples: Nasopharyngeal flocked swabs (COPAN) were collected and analyzed for the presence of influenzavirus (INF) A/B, respiratory syncytial virus (RSV), parainfluenzavirus (PIV) 1-4, human rhinoviruses (HRV), human metapneumovirus (hMPV), Bocavirus (Boca), coronaviruses (COR) OC43, NL63, 229E, adenovirus (ADE), as well as the novel polyomaviruses KI and WU. V0 samples (1185) were taken from age-, sex-, and geographically-matched controls; V2 samples (2544) were collected from the same patients – 4 weeks after V1. Here, we present primary etiological data and report on the relative importance of quantitative measurements (Ct values), as well as the aetiology of double infections. Analysis:Specimens were transported to the central lab in Antwerp for nucleic acid extraction by the NucliSensEasyMAG (bioMerieux); isolates were analyzed by RT-PCR either directly (DNA viruses) or after cDNA synthesis by using a Multiscribe reverse transcriptase kit together with random hexamers (Applied Biosystems). Viral loads were determined by the number of amplification cycles needed for a positive TaqManrealtime PCR test (cycle treshold, CT). Samples were counted positive for CT<40. CONCLUSIONS The relative importance of respiratory viruses in lower respiratory tract infections in primary care. [P1581] F. Coenjaerts1, C. Lammens2, M. Viveen1, L. Tan1, K. Loens2, H. Goossens2 , P. Zuithoff3, M. Ieven2, A. van Loon1, and E. Claas4 on behalf of the GRACE study team 1 Univ. Med. Centre Utrecht – Dept. of Med. Microbiology, The Netherlands; 2 University of Antwerp, Belgium; 3 UMC Utrecht – Julius Center; 4 UMC Leiden, the Neth. * Differing significantly from V1 Presentation rates of respiratory pathogens in V1 samples significantly exceed those found in controls (V0) and follow up (V2) samples; this does not hold true for Boca-, WU and KI virus, which might question them as true respiratory pathogens. The availability of quantitative viral load data is unlikely to affect individual patient management. Double infections do not affect patient presentation rates; even in control patients follow up visits double infections do occur. This project is supported through Priority 1 (Life Sciences, Genomics and Biotechnology for Health) of European Union's FP6, Contract number: LSHM-CT-2005-518226 www.grace-lrti.org Correspondence: f.e.j.coenjaerts@umcutrecht.nl Positive follow up (V2; columns) after specific V1 pathogens (rows); depicted P values indicating strong trends (P values <0.10) or significant associations (P values < 0.05).