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. 2010 Jan 15;50(2):202-9.
doi: 10.1086/648678.

Etiology of community-acquired pneumonia: increased microbiological yield with new diagnostic methods

Niclas Johansson  1 , Mats Kalin, Annika Tiveljung-Lindell, Christian G Giske, Jonas Hedlund
Affiliations

Etiology of community-acquired pneumonia: increased microbiological yield with new diagnostic methods

Niclas Johansson et al. Clin Infect Dis. .

Abstract

Background: The microbial etiology of community-acquired pneumonia (CAP) is still not well characterized. During the past few years, polymerase chain reaction (PCR)-based methods have been developed for many pathogens causing respiratory tract infections. The aim of this study was to determine the etiology of CAP among adults-especially the occurrence of mixed infections among patients with CAP-by implementing a new diagnostic PCR platform combined with conventional methods.

Methods: Adults admitted to Karolinska University Hospital were studied prospectively during a 12-month period. Microbiological testing methods included culture from blood, sputum, and nasopharyngeal secretion samples; sputum samples analyzed by real-time quantitative PCR for Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis; nasopharyngeal specimens analyzed by use of PCR; serological testing for Mycoplasma pneumoniae, Chlamydophila pneumoniae, and viruses common in the respiratory tract; and urine antigen assays for detection of pneumococcal and Legionella pneumophila antigens.

Results: A microbial etiology could be identified for 67% of the patients (n = 124). For patients with complete sampling, a microbiological agent was identified for 89% of the cases. The most frequently detected pathogens were S. pneumoniae (70 patients [38%]) and respiratory virus (53 patients [29%]). Two or more pathogens were present in 43 (35%) of 124 cases with a determined etiology.

Conclusions: By supplementing traditional diagnostic methods with new PCR-based methods, a high microbial yield was achieved. This was especially evident for patients with complete sampling. Mixed infections were frequent (most commonly S. pneumoniae together with a respiratory virus).

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Figures

Figure 1
Figure 1
Percentage of patients with complete samples collected (n = 38) whose case of infection was etiologically determined and percentage of mixed infections. H. influenzae, Haemophilus influenzae; M. catarrhalis, Moraxella catarrhalis; M. pneumoniae, Mycoplasma pneumoniae; N. cyriacigeorgica, Nocardia cyriacigeorgica; RSV, respiratory syncytial virus; S. pneumoniae, Streptococcus pneumoniae.
See this image and copyright information in PMC

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