A 19 year old female with a history of sickle cell disease presents to the ED with fever, cough and chest pain. A chest xray shows a consolidation in the right lower lung. Which of the following is the most commonly identified pathogen in acute chest syndrome? (scroll down for the answer)

a) Chlamydia pneumoniae

b) Streptococcus pneumoniae

c) Staphylococcus aureus

d) Parainfluenza virus

e) Klebsiella pneumonia

The correct answer is a) Chlamydia pneumoniae

While streptococcus was previously the most frequent cause of infection in acute chest, more recently it has been surpassed by the atypical agents: chlamydia pneumonia and Mycoplasma pneumonia (with chlamydia being the more common of the two). This is thought to be due to the use of pneumonoccal immunization and prophylactic penicillin therapy.¹ All of the above organs can be associated with acute chest syndrome.

ACEP News published a clinical practice bulletin on Acute Chest Syndrome which can be found here: https://www.acep.org/Clinical---Practice-Management/Focus-On--Acute-Chest-Syndrome---The-Critical-Cough/#sm.00000sw33g8vywdpavr1t36o4bz67

References:

¹ Stapczynski, J. Stephan,, and Judith E. Tintinalli. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York, N.Y.: McGraw-Hill Education LLC., 2011. Page 1506-1508.

Vichinsky, EP., et al. Causes and Outcomes of the Acute Chest Syndrome in Sickle Cell Disease. N Engl J Med. 2000;342:1855-1865. http://www.nejm.org/doi/full/10.1056/NEJM200006223422502#t=abstract