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Researchers Identify Characteristics of Patients With Legionella Spp. Community-Acquired Pneumonia: Presented at ECCMID-ICC

By Chris Berrie

MUNICH, GERMANY -- April 10, 2007 -- Legionella spp. is the second most frequently identified pathogen causing community-acquired pneumonia (CAP) in Germany, and it is associated with a serious clinical course, according to a study presented here on April 2^nd at the joint 17^th European Congress of Clinical Microbiology and Infectious Diseases and 25^th International Congress on Chemotherapy (ECCMID-ICC).

Heike von Baum, MD, coordinator of central study unit and head, infection control unit, Ulm University Clinic, Ulm, Germany, presented this study on behalf of the Competence Network for Community-Acquired Pneumonia (CAPNETZ).

To determine the role of Legionella spp. in the development of CAP in Germany, full demographic, clinical and diagnostic data from 2,503 patients with CAP in 10 centres across Germany were recorded and analysed.

The analysis included Gram-stain culturing of respiratory samples using polymerase chain reaction (PCR) for Legionella spp., Mycoplasma spp. and Clamydia spp., as well as viral pathogens. Urine samples were analysed for Legionella spp. and for pneumococci, as were serum samples for Legionella spp., Mycoplasma spp. and Clamydia spp.

Starting from 2,503 patient samples, culture of respiratory material from 479 of these was positive for Legionella spp. infection in 3 patients (0.12%), while PCR analysis of 904 samples from respiratory material gave 69 (2.8%) positives. Similarly, urinary antigen tests on 2,232 samples were positive for 49 (2.2%), and serology of 2,495 samples were positive for 34 (1.4%).

Overall, the researchers confirmed that CAP was caused by Legionella spp. Infection in 4.2% of patients in the sample, which indicating that this is the second most frequently identified pathogen causing CAP in Germany, Dr. von Baum said.

"Our next question was whether we could identify specific clinical characteristics in these patients with CAP," she said.

The researchers identified the clinical characteristics associated with pneumococci infection as follows: age; outpatient care; high score on the Confusion Respiratory rate Blood Pressure 65 (CRB 65) scale; current smoking; packyears smoked; altered mental status; patient death. Among patients whose sputum was obtained, it was more likely to be purulent in patients with pneumococcal infection.

Patient characteristics identified as being associated with Legionella infection were: age; male gender; high CRB 65 score; current smoking; packyears smoked; diabetes; patient death. Despite the dry cough associated with Legionella spp. infection, sputum was obtained more often in patients with this infection (47% vs 27%), and it was purulent less often than in those who did not have this bacterium (48% vs 58%).

The mean number of antibiotic therapies used in patients with Legionella and Pneumococci infections were equal (1.4), and included: aminopenicillins (5% vs 4%); aminopenicillins plus inhibitor (31% vs 30%); cephalosporins (second/third: 14%/19% vs 16%/25%); macrolides and ketolides (47% vs 38%); and fluoroquinolones (24% vs 21%). Patients with Legionella infection received slightly more atypical active substances (69% vs 60%).

Dr. von Baum stressed the role of Legionella spp. as a serious cause, and as the second most frequent cause of CAP in Germany. She noted that these patients with Legionella pneumonia share no significant distinct clinical characteristics that would aid in their immediate diagnosis. However, in comparison with patients with CAP caused by Pneumococci spp., there are more deaths with CAP caused by Legionella spp.


[Presentation title: Legionella Spp. Causing Community-Acquired Pneumonia in Germany. Data From the Competence Network for Community-Acquired Pneumonia (CAPNETZ). Abstract O271]

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