by Rosalyn Carson-DeWitt, MD
En Espaol (Spanish Version) Atypical pneumonia is a lung infection.
Typical pneumonia is a severe illness. It is usually caused by bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, or Klebsiella pneumoniae . Typical pneumonia tends to strike older individuals, especially those with heart or lung conditions.
In contrast, atypical pneumonia tends to be a milder illness. It is caused by a different assortment of bacteria or viruses, and it usually strikes healthy young people.
All types of pneumonia are potentially serious conditions that require care from your doctor.

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Atypical pneumonia is usually caused by:
- Bacteria
- Mycoplasma pneumoniae
- Chlamydia bacteria
- Coxiella burnetii
- Legionella
- Viruses
The following factors increase your chance of developing atypical pneumonia:
- Being a child, adolescent, or young adult
- Living in closed communities, such as dormitories in boarding schools or colleges, and military barracks
- Cigarette smoking
- Lung disease
- Weakened immune system
If you experience any of these symptoms, do not assume the cause is due to pneumonia. These symptoms may be caused by other, less serious health conditions.
Fever (mild)Enlarged lymph nodesRed eyesChillsCough, often drySore throatPhlegm (sputum) productionMuscle aches and painsDecreased appetiteHeadacheChest painShortness of breathFast breathingIntense fatigueWeaknessVomitingDiarrheaSkin rash Diagnosis Your doctor will ask about your symptoms and medical history, and perform a physical exam. Tests may include the following: Chest x-ray looking at your lungs with a chest x-ray may reveal pneumonia Blood teststesting your white blood cells can determine whether you are experiencing a bacterial or a viral infection. Other blood tests (eg, cold agglutinins) can identify the presence of certain bacteria or viruses.Blood culturesbacteria or viruses may be grown from samples of your blood in a laboratory. The specific type of bacteria or virus can then be identified, so that you can receive appropriate treatment.Sputum testif you are coughing up sputum, you may be asked to collect some in a sterile container for testing. This can reveal what type of bacteria is causing your illness, so the correct treatment can be started. TreatmentTalk with your doctor about the best treatment plan for you. Treatment options include the following: AntibioticsUsually, atypical pneumonia due to bacteria can be treated with oral antibiotics at home. However, more severe pneumonia may require intravenous antibiotics in the hospital. Some of the antibiotics used to treat atypical pneumonia include erythromycin, azithromycin, and clarithromycin.
Viral pneumonia will not respond to antibiotic treatment. OxygenIf you are severely ill from pneumonia, you may need extra oxygen. Prevention To help reduce your chances of getting pneumonia, take the following steps: Use good hand-washing techniques.Avoid contact with other ill people.Follow your doctors recommendations for treating any chronic conditions. RESOURCES: American Lung Associationhttp://www.lungusa.org National Institute for Allergies and Infectious Diseasehttp://www3.niaid.nih.gov CANADIAN RESOURCES: BC Childrens Hospitalhttp://www.bcchildrens.ca/default.htm The Canadian Lung Associationhttp://www.lung.ca References: Blasi F, Tarsia P, Aliberti S, et al. Chlamydia pneumoniae and mycoplasma pneumoniae. Semin Respir CritCare Med . 2005; 26:617-24. Cantu S. Mycoplasma pneumonia. eMedicine website. Available at: http://www.emedicine.com . Accessed February 26, 2006. Cunha BA. The atypical pneumonias: clinical diagnosis and importance. Clin Microbiol Infect . 2006;12 (Suppl)3:12-24. Donowitz GR, Mandell GL, eds. In: Principles and Practice of Infectious Diseases. 5th ed. London: Churchill Livingstone Inc; 2000.
Goetz MB, et al., eds. Pyogenic Bacterial Pneumonia, Lung Abscess, and Empyema. In: Mason R J, et al., eds. Murray & Nadels Textbook of Respiratory Medicine. 4th ed. London: Elsevier; 2005. Schlossberg D. Mycoplasmal Infection. In: Goldman L, et al., eds. Cecil Textbook of Medicine. 22nd ed. Philadelphia: WB Saunders Company; 2004. Thibodeau KP, Viera A.J. Atypical pathogens and challenges in community-acqiured pneumonia. Am Fam Physician . 2004;69:1699-706. Last reviewed January 2008 by David Juan, MDPlease be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.