Atypical pneumonia is an infection of the lungs caused by a variety of bacteria, viruses, or fungi that typically show atypical symptoms compared to other types of pneumonia. The most common causes of atypical pneumonia are Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, and Coxiella burnetii.
Mycoplasma pneumoniae is an organism found in the upper respiratory tract and is responsible for up to 30% of all cases of atypical pneumonia. This bacterium is spread through airborne droplets from coughing or sneezing and is more common in children and young adults. Symptoms of Mycoplasma pneumoniae include fever, chills, chest pain, dry cough, headache, and fatigue.
Chlamydophila pneumoniae is a bacterium that is spread through contact with infected secretions, such as saliva or nasal mucus. This organism is the most common cause of atypical pneumonia in adults and typically causes milder symptoms than other forms of pneumonia. Symptoms of Chlamydophila pneumoniae include fever, chills, chest pain, dry cough, headache, and fatigue.
Legionella pneumophila is a bacterium commonly found in water, soil, and air. This organism can be spread through contaminated mist, such as from air conditioning systems or showers. Symptoms of Legionella pneumophila include fever, chills, chest pain, dry cough, headache, and fatigue.
Coxiella burnetii is a bacterium found in livestock, which can be spread through contact with infected animals, such as sheep or cattle, or through inhalation of contaminated dust particles. Symptoms of Coxiella burnetii include fever, chills, chest pain, dry cough, headache, and fatigue.
Other potential causes of atypical pneumonia include viruses and fungi. Viral pneumonia is typically milder than bacterial pneumonia and is caused by a variety of viruses, including influenza and respiratory syncytial virus. Fungal pneumonia is caused by a variety of fungi and is more common in people with weakened immune systems, such as those with chronic illnesses or those taking immunosuppressive medications. Symptoms of both viral and fungal pneumonia include fever, chills, chest pain, dry cough, headache, and fatigue.