Rapid Aetiological Diagnosis of Pneumonia Based on Routine Laboratory Features

Abstract

The values of some basic laboratory features on admission to hospital were recorded and compared in 418 adult patients with community-acquired pneumonia, namely erythrocyte sedimentation rate, C-reactive protein, white blood cell (WBC) count, serum lactate dehydrogenase (S-LD), serum alanine-aminotransferase, and serum sodium. Discriminant analysis was performed to obtain an aetiological diagnosis. WBC value of greater than 15 x 10(9)/l strongly indicated a bacterial and, especially a pneumococcal aetiology, whereas increased S-LD could imply a mycoplasmal infection. For patients less than 50 years of age the equation C2 = -1.788 + 0.204 x WBC-0.0909 X S-LD was constructed, in which C2 greater than 0 indicated a pneumococcal aetiology. This function correctly classified 31/33 (93.9%) patients with a mycoplasmal and 20/31 (64.5%) patients with a pneumococcal infection. Patients with viral, Haemophilus influenzae or chlamydial infection could not be discriminated from each other. The age of the patient, WBC and possibly S-LD on admission are easily accessible parameters and these results could therefore be of value in daily clinical practice in hospitals.

Usefulness of consecutive C-reactive protein measurements in follow-up of severe community-acquired pneumonia

“…Concerning the influence of the causative pathogen on the decay of CRP, a slower decline in CRP levels was observed in the first 3 days of follow-up in L. pneumophila than in other pathogens. This may be due to inappropriate empirical treatment; however, all patients had Legionella antigen test performed within 12 h and patients with a positive Legionella antigen test received treatment for Legionella infection within 12 h. Another explanation may be that L. pneumophila, as an intracellular pathogen, causes a different host response to infection, characterised by prolonged and greater increases of CRP [25,26]. According to these results, the causative pathogens need to be taken into account in order to interpret CRP levels in follow-up correctly.…”

C-reactive protein levels in community-acquired pneumonia

“…Pneumonia due to C. burnetii, C. psitacci, C. pneumoniae, M. pneumoniae and respiratory viruses is usually mild, though L. pneumophila pneumonia may be severe and its detection can be of epidemiological importance. Regarding the aetiological diagnosis of pneumonia, clinical and chest radiographical findings lack accuracy [14,15] cultures take at least 24 h to produce a positive result and specific rapid tests based on the detection of soluble antigens of S. pneumoniae or L. pneumophila in body fluids are not always available. Therefore, initial antibiotic therapy is usually chosen on an empirical basis [16].…”

Assessment of the Usefulness of Sputum Culture for Diagnosis of Community-Acquired Pneumonia Using the PORT Predictive Scoring System

“…A causative agent is identified in 30% to 40% of cases, and the most common is Streptococcus pneumoniae. The clinical and radiographic microbiological diagnoses of pneumonia lack accuracy, 1,2 cultures take at least 24 hours to produce a positive result, and specific rapid tests based on the detection of soluble antigens of S pneumoniae or Legionella pneumophila in body fluids are not always available. Therefore, initial antibiotic therapy is usually empirically chosen.…”