What is atypical pneumonia?

Definition

Atypical pneumonia is a lung infection. It tends to be a mild illness in
comparison with typical pneumonia, which is a severe illness.
Typical pneumonia is usually caused by bacteria such as Streptococcus
pneumoniae, Haemophilus influenzae, or
Klebsiella pneumoniae, and it tends to strike older persons,
especially those with heart or lung conditions.

In contrast, atypical pneumonia 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 a doctor.

Causes

Atypical pneumonia is usually caused by bacteria such as Mycoplasma pneumoniae
, Chlamydia
, Coxiella burnetii
, and Legionella
, and by viruses.

Risk Factors

The following factors increase the 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 in military barracks; cigarette smoking; lung disease; and a weakened immune system.

Symptoms

The following symptoms are not necessarily caused by pneumonia and might be caused by other, less serious health conditions: fever (mild); enlarged lymph nodes; red eyes; chills; cough, often dry; sore throat; phlegm (sputum) production; muscle aches and pains; decreased appetite; headache; chest pain; shortness of breath; fast breathing; intense fatigue; weakness; vomiting; diarrhea; and skin rash.

Screening and Diagnosis

A doctor will ask about the infected person’s symptoms and medical history and
will perform a physical exam. Tests may include a chest X ray; blood tests
(testing white blood cells, which can determine if the person has a
bacterial or viral infection); other blood tests,
which might identify the presence of certain bacteria or viruses; blood cultures
(in which bacteria or viruses may be grown from blood samples); and a sputum test.
If the person is coughing up sputum, he or she may be asked to collect some of
that sputum in a sterile container for testing; this test can reveal what type of
bacterium is causing the illness.

Treatment and Therapy

If diagnosed with pneumonia, one should follow instructions from the doctor.
Usually, atypical pneumonia caused by bacteria can be treated with oral
antibiotics at home. However, more severe pneumonia may require intravenous
antibiotics in a hospital. Some of the antibiotics used to treat atypical
pneumonia include erythromycin, azithromycin, and clarithromycin.

Viral pneumonia will not respond to antibiotic treatment. If the person is severely ill from pneumonia, he or she may need extra oxygen.

Prevention and Outcomes

To help reduce the chances of getting pneumonia, one should use good handwashing technique, should avoid contact with other ill people, and should be treated for any chronic conditions.

Bibliography

Blasi, F., et al. “ Chlamydia pneumoniae and Mycoplasma pneumoniae.” Seminars in Respiratory and Critical Care Medicine 26 (2005): 617-624.

Cunha, B. A. “The Atypical Pneumonias: Clinical Diagnosis and Importance.” Clinical Microbiology and Infection 12, suppl. 3 (2006): 12-24.

_______. “Atypical Pneumonias: Current Clinical Concepts Focusing on Legionnaires’ Disease.” Current Opinion in Pulmonary Medicine 14 (2008): 183-194.

Goetz, M. B. “Pyogenic Bacterial Pneumonia, Lung Abscess, and Emphysema.” In Murray and Nadel’s Textbook of Respiratory Medicine, edited by Robert J. Mason et al. 5th ed. Philadelphia: Saunders/Elsevier, 2010.

Mandell, Gerald L., John E. Bennett, and Raphael Dolin, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases. 7th ed. New York: Churchill Livingstone/Elsevier, 2010.

Rosenow, E. “Walking Pneumonia: What Does It Mean?” Mayo Clinic. Available at http://www.mayoclinic.com.

Schlossberg, D. “Mycoplasmal Infection.” In Andreoli and Carpenter’s Cecil Essentials of Medicine, edited by Thomas E. Andreoli et al. 8th ed. Philadelphia: Saunders/Elsevier, 2010.

Thibodeau, K. P., and A. J. Viera. “Atypical Pathogens and Challenges in Community-Acquired Pneumonia.” American Family Physician 69 (2004): 1699-1706.

West, John B. Pulmonary Pathophysiology: The Essentials. 7th ed. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, 2008.