Pneumonia

Keywords: Psittacosis

Causes

Appropriate Tests

 

See pneumonia requiring hospital admission in the Guideline on Pathology testing in the Emergency department: Appendix 2.

MCS sputum; Blood culture. If indicated: Full blood count, Blood film, White cell count differential; Electrolytes, Creatinine, Urea; Blood gas arterial.

Consider MCS sputum, respiratory virus PCR and relevant serology.

Non-infective processes may also be responsible for radiological changes, eg carcinomatosis, lymphoma, systemic necrotising vasculitis.

Urine antigen for streptococci (adults) and Legionella pneumophila serogroup 1 Ag.

Lobar and bronchopneumonia

Occasionally, in severe pneumonia unresponsive to initial therapy, investigations may include MCS Bronchoalveolar lavage (bronchial brush, wash; bronchoalveolar lavage), Fine needle aspiration biopsy or endoscopic lung biopsy, including microscopy and culture. Pleural fluid examination may be indicated if pleural effusion is present.

Streptococcus pneumoniae

 

Legionella pneumophila

See Legionella infection

Haemophilus influenzae

See Haemophilus influenzae infection

Klebsiella pneumoniae

 

Burkholderia pseudomallei

 

Aspiration pneumonia

Predisposing conditions include unconsciousness, alcohol intoxication.

Mixed bacterial infection, including anaerobic organisms

 

'Atypical' pneumonia

The clinical signs are not typical of pneumonia and consolidation appears diffuse or unusual on diagnostic imaging.

Mycoplasma pneumoniae

See Mycoplasma infection

Legionella spp

See Legionella infection

Chlamydia psittaci

 

Chlamydia Ab.

Chlamydia pneumoniae

Chlamydia pneumoniae Ab.

Viral infection

  • Influenza A, B
  • Adenovirus
  • Coronavirus, including SARS agent

Influenza virus Ab, Adenovirus Ab. 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' pneumonia

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)

Immunocompromised host

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: MCS sputum, MCS Bronchoalveolar lavage (bronchial brush, wash; bronchoalveolar lavage), Fine needle aspiration biopsy or endoscopic lung biopsy - microscopy, culture (including mycobacterial and fungal). Open lung biopsy may be required.

Mycobacterial infection

  • Tuberculosis
  • Non-tuberculous mycobacteria

Sputum culture for M tuberculosis, Quantiferon Gold serological test, Mantoux test if not immunocompromised or kn0wn active TB.

Pneumocystis jiroveci

See Pneumocystis infection

Nocardia spp

 

Cytomegalovirus

See Cytomegalovirus infection

Gram-negative bacilli

 

Fungal infection

 

  • Cryptococcus neoformans

See Cryptococcal infection

  • Aspergillus spp

See Aspergillosis

Neonates/Infants

See Neonatal sepsis

Viral pneumonia, especially

  • Respiratory syncytial virus

Virus detection; Culture - Nasopharyngeal swab/aspirate.

  • Cytomegalovirus

See Cytomegalovirus infection

Chlamydia trachomatis infection

 

Bacterial pneumonia, especially

  • Staphylococcus aureus

 

Pneumonia with abscess

MCS pus obtained at bronchoscopy, Fine needle aspiration biopsy.

Aspiration pneumonia, especially

Examination of expectorated sputum may be of little value.

  • Staphylococcal infection

Particularly in infants.

Secondary to bronchial obstruction

  • Tumour
  • Foreign body

Bronchial brushings for cytology; lesion biopsy.

Patients with Bronchiectasis and/or Cystic fibrosis

 

Staphylococcus aureus

 

Pseudomonas aeruginosa

 

Burkholderia cepacia

 

Interstitial pneumonia

See Interstitial lung disease