Chest infections

What is Chest infection ?

A chest infection, also known as a respiratory infection, refers to an infection of the respiratory tract by a pathogen (viral, bacterial, mycobacterial or fungal). Here we will refer to infection of the lower respiratory tract, which is also termed lung infection. 

The infection can involve the large airways (e.g. bronchitis), the small airways (e.g. bronchiolitis) or the lung tissue (e.g. pneumonia). 

Infections are also drivers of exacerbations of underlying lung disease, also referred to as flare-ups. For example, infections can lead to exacerbations of COPD, asthma, bronchiectasis and interstitial lung disease.

Chest infection covid

What are the common causes of a chest infection?

Gram-positive bacteria

  • Streptococcus pneumoniae
  • Staphylococcus aureus

Gram-negative bacteria

  • Haemophilus influenzae
  • Moraxella catarrhalis
  • Mycoplasma pneumoniae
  • Pseudomonas aeruginosa
  • Klebsiella pneumoniae
  • Acinetobacter baumanii
  • Stenotrophomonas maltophilia
  • Escherichia coli

Viruses

  • Respiratory syncytial virus
  • Rhinovirus
  • Adenoviruses
  • Human Metapneumovirus
  • Influenza viruses
  • Parainfluenza viruses
  • Coronaviruses (including SARS-CoV-2)

Mycobacterium

  • Mycobacterium tuberculosis

Non-tuberculous mycobacterium

  • M. Avium
  • M. Fortuitum
  • M. Chelonae
  • M. Kansasii
  • M. Abscessus
  • M. Xenopii
  • M. Szulgai
  • M. Malmoense

Fungal

  • Aspergillus species
  • Cryptococcus species
  • Pneumocystis Jirovecii
  • Endemic mycoses
chest infection bacteria
Medication

What are the symptoms of chest infection?

 

What are the risk factors for a chest infection?

  • Respiratory disease (e.g. bronchiectasis, COPD, asthma, interstitial lung disease)
  • Smoking
  • Advanced age
  • Immunodeficiency (e.g. Primary immunodeficiency, HIV, cancer, immunosuppressant medication)
  • Malnutrition
  • Neurological conditions affecting swallow (e.g. Stroke)

What investigations are needed for chest infections?

  • Radiological  – Chest x-ray or Computed Tomography (CT) scan of the chest
  • Microbiological investigations – Sputum cultures for bacteria, mycobacteria and fungi, PCR for viruses
  • Blood tests – markers of inflammation and assessment of immune function
  • Other investigations may be needed if co-existing co-morbidities are identified (e.g. video fluoroscopy if history of aspiration)

How are chest infections treated?

The treatment will depend on the cause. 

General measures include resting and taking analgesics or anti-inflammatory medication to reduce fever and pain are helpful.

Viral infections usually resolve on their own and don’t require specific treatment other than general measures. In specific cases antiviral medication can be used (e.g. Oseltamivir for Influenza virus and Remdesivir for SARS-CoV-2).

Bacterial infections are treated with antibiotics. The type of antibiotic and duration of the treatment will depend on the suspected or identified pathogen as well as associated. co-morbidities. 

Mycobacterial infections are treated with a combination of antimicrobials. The duration of treatment depends on the identified mycobacterium (e.g. 6 months for pulmonary tuberculosis and 18-24 months for non-tuberculous mycobacteria). 

Fungal infections are treated with anti-fungal drugs (e.g. itraconazole, voriconazole, posaconazole, caspofungin, micafungin, amphotericin, terbenefine).

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