Saturday, December 27, 2014

E. Staphylococcus epidermidis

Which of the following organisms is most likely to cause infection of a shunt implanted for the treatment of hydrocephalus?

A. Bacteroides fragilis
B. Corynebacterium diphtheriae
C. Escherichia coli
D. Staphylococcus aureus
E. Staphylococcus epidermidis

The answer is E. Probably because of its ubiquity and ability to stick to foreign
surfaces, Staphylococcus epidermidis is the most common cause of infections of central
nervous system shunts as well as an important cause of infections on artificial heart valves
and orthopedic prostheses.

Corynebacterium spp. (diphtheroids), similar to S. epidermidis,colonize the skin. When these organisms are isolated from cultures of shunts, it is often difficult to be sure if they are the cause of disease or simply contaminants. Leukocytosis in cerebrospinal fluid, consistent isolation of the same organism, and the character of a patient’s symptoms are all helpful in deciding whether treatment for infection is indicated.


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