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.

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

What are the symptoms of chest infection?

A cough productive of phlegm (mucus)
Coughing blood (haemoptysis)
Shortness of breath
Wheeze
Chest pain
Fever
Muscle aches
Fatigue

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).

Dr Jose is a chest specialist with specialist expertise in the management of chest infections.