Prospective Study of Community-Acquired Pneumonia of Bacterial Etiology in Adults

Abstract

The aim of this study was to prospectively analyze the bacterial etiology of community-acquired pneumonia in adults in Spain. From May 1994 to February 1996, 392 episodes of CAP diagnosed in the emergency department of a 600-bed university hospital were studied. An etiological diagnosis based on noninvasive microbiological investigations was achieved in 228 cases (58%); 173 of these diagnoses were definitive and 55 probable. Streptococcus pneumoniae, which caused 23.9% of the episodes, was the predominant pathogen observed, followed by Chlamydia pneumoniae (13.5%) and Legionella pneumophila (12.5%). Other less frequent pathogens found were Haemophilus influenzae (2.3%), Pseudomonas aeruginosa (1.5%), Mycoplasma pneumoniae (1.3%), Coxiella burnetii (1%), Moraxella catarrhalis (2 cases), Nocardia spp. (2 cases), and Staphylococcus aureus (2 cases). Streptococcus pneumoniae was significantly more frequent in patients with underlying disease and/or age > or =60 years (28% vs. 13%, P = 0.002), while Legionella pneumophila was more frequent in patients below 60 years of age and without underlying disease (20% vs. 9%, P = 0.006). Likewise, Streptococcus pneumoniae and Legionella pneumophila were the most frequent etiologies in patients requiring admission to the intensive care unit, occurring in 29% and 26.3% of the patients, respectively. In addition to Streptococcus pneumoniae, other microorganisms such as Chlamydia pneumoniae and Legionella spp. should be seriously considered in adults with community-acquired pneumonia when initiating empiric treatment or ordering rapid diagnostic tests.

Atypical pathogen infection in community-acquired pneumonia

“…Global mortality at 28 days in severe CAP was 25% and that of L. Pneumophila was 33.3% (three of nine cases), but the difference was not significant with non-Legionella severe CAP mortality (33% vs 24.5%) (33). There is a relatively high incidence of L. Pneumophila in global CAP, particularly in the United States (14%) (12) and Spain (12.5%) (34). Even in Asia, the incidence is as high as 6.6% (32).…”

Feature Selection, Ranking of Each Feature and Classification for the Diagnosis of Community Acquired Legionella Pneumonia

“…LCAP pneumonia has a high prevalence among CAP pneumonias being considered as the third highest cause of CAP (18,4). In most studies early diagnosis of LCAP is difficult because other NLP pneumonias may present with a similar clinical picture and microbiologic CAP tests are not always available or have only retrospective value.…”

“…In Europe, Streptococcus pneumoniae is the most frequently identified pathogen, followed by different microorganisms according to the series reviewed. Although Legionella species has been considered as a rare cause of CAP, more recent series have implicated this pathogen in 8% -15% of the cases (2,3,4). Diagnosis of Legionella pneumonia is commonly performed retrospectively by serology study or tardy by isolation in special culture mediums from clinical samples.…”

Diagnosis and Treatment of Community‐Acquired Pneumonia

“…Based on these findings, other researchers 13 concluded that a positive blood culture had no correlation with the severity of the illness or outcome. Another prospective study 10 showed that blood cultures were positive in only 10.5 percent of patients with pneumonia. Despite these and …”

“…Furthermore, sputum samples are adequate in only 52.3 percent of patients with CAP, and only 44 percent of those samples contain pathogens. 10 Nonetheless, initial therapy often is guided by the assumption that the presenting disease is caused by a common bacterial pathogen. Findings 11 also cast doubt on the clinical utility of obtaining blood cultures from patients with suspected CAP.…”