Noninvasive methods for the diagnosis of pneumonia

Despite the proliferation of diagnostic procedures, pneumonia remains a clinical and therapeutic challenge. The approach to the patient is directed toward identifying aetiological agents and instituting the treatment of choice for the infection. However, the initial treatment is often empirical due to the difficulties in obtaining a precise aetiological diagnosis and the potential severity of the illness. Noninvasive methods for aetiological diagnosis of pneumonia still represent the cornerstone of microbiological diagnosis. The time-honoured but criticized Gram's stain and sputum culture are now supported by newer techniques such as antigen detection, molecular biology etc. that improve the sensitivity and specificity of pathogen identification. This paper reviews new and old noninvasive techniques with respect to accuracy, reliability and clinical relevance in the etiological diagnosis of pneumonia.