Last updated: Friday, 24, December, 2010
Sputum - microscopy and culture; blood culture. If indicated: FBC, blood film, differential WCC; electrolytes, creatinine, urea; blood gases. Non-infective processes may also be responsible for radiological changes, eg carcinomatosis, lymphoma, systemic necrotising vasculitis.
Lobar and bronchopneumonia
Occasionally, in severe pneumonia unresponsive to initial therapy, investigations may include bronchial brush, wash; bronchoalveolar lavage, FNAB or endoscopic lung biopsy, including microscopy and culture. Pleural fluid examination may be indicated if pleural effusion is present.
Predisposing conditions include unconsciousness, alcohol intoxication.
Mixed bacterial infection, including anaerobic organisms
The clinical signs are not typical of pneumonia and consolidation appears diffuse or unusual on diagnostic imaging.
Chlamydia pneumoniae antibodies.
Influenza virus antibodies, adenovirus antibodies. Viral culture, detection only indicated for severe pneumonia, eg immunocompromised patients, patients requiring ICU admission, or in an outbreak setting, eg SARS 2003, avian influenza 2004, in defined at-risk patients.
Opportunistic infections may occur in immunocompromised or normal hosts and this possibility should be considered when there is failure to respond to initial antibiotic therapy. If appropriate: HIV antibodies, assessment of immune function.See also Infection (increased susceptibility)
The common pathogens are the most likely cause of pneumonia, but unusual pathogens should be considered early, especially when the illness is severe or when the initial response to therapy is unsatisfactory. Investigation may include: sputum microscopy and culture, bronchial brush, wash; bronchoalveolar lavage, FNAB or endoscopic lung biopsy - microscopy, culture (including mycobacterial and fungal). Open lung biopsy may be required.
See Neonatal sepsis
Viral pneumonia, especially
Virus detection, culture - nasopharyngeal aspirate.
Chlamydia trachomatis infection
Bacterial pneumonia, especially
Pneumonia with abscess
Microscopy and culture of pus obtained at bronchoscopy, FNAB.
Aspiration pneumonia, especially
Examination of expectorated sputum may be of little value.
Particularly in infants.
Secondary to bronchial obstruction
Bronchial brushings for cytology; lesion biopsy.
Patients with bronchiectasis and/or cystic fibrosis
See also cough - chronic