View source for WBR0712

{{WBRQuestion
|QuestionAuthor=William J Gibson (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|MainCategory=Microbiology
|SubCategory=Endocrine, Infectious Disease
|MainCategory=Microbiology
|SubCategory=Endocrine, Infectious Disease
|MainCategory=Microbiology
|SubCategory=Endocrine, Infectious Disease
|MainCategory=Microbiology
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Endocrine, Infectious Disease
|MainCategory=Microbiology
|SubCategory=Endocrine, Infectious Disease
|MainCategory=Microbiology
|SubCategory=Endocrine, Infectious Disease
|MainCategory=Microbiology
|SubCategory=Endocrine, Infectious Disease
|MainCategory=Microbiology
|MainCategory=Microbiology
|SubCategory=Endocrine, Infectious Disease
|Prompt=A 19-year-old woman presents to the emergency department for sudden onset fatigue, fever, headache, and vomiting over the past 6 hours. Thirty minutes after presentation, she decompensates rapidly. Her temperature rises to 40 ˚C (104 ˚F), her blood pressure drops to 70/40 mmHg and she loses consciousness. Examination reveals diffuse petechiae, predominantly over the lower extremities. CT scan reveals bilateral adrenal hemorrhage. Which of the following is the most likely organism responsible for this patient's condition?
|Explanation=The patient in this vignette has [[Waterhouse–Friderichsen syndrome]] ([[WFS]]), in which a bacterial infection leads to massive hemorrhage into one or (usually) both adrenal glands. WFS is most commonly caused by overwhelming blood-borne infection with ''[[Neisseria meningitidis]]'', and is the most severe form of meningococcal septicemia. The onset of the illness is typically nonspecific with fever, rigors, vomiting, and headache. These symptoms are often followed by a macular rash that rapidly becomes petechial and purpuric with a dusky gray color. Hypotension develops and rapidly leads to septic shock. Extremities often become visibly cyanotic and patients can become comatose. Surprisingly, in this form of meningococcal disease, [[meningitis]] generally does not occur. [[Disseminated intravascular coagulation]] occurs along with the hallmark [[adrenal hemorrhage]] leading to [[adrenocortical insufficiency]] and often death. Other causes of WFS include ''Pseudomonas aeruginosa'', ''Streptococcus pneumoniae'', and ''Mycobacterium tuberculosis''.
|AnswerA=''Listeria monocytogenes''
|AnswerAExp=''[[Listeria monocytogenes]]'' can cause [[listeriosis]] and can be introduced to a host via oral exposure from spoiled food products like milk. It is not associated with WFS.
|AnswerB=''Neisseria meningitidis''
|AnswerBExp=''[[Neisseria meningitidis]]'' is the classical cause of [[Waterhouse–Friderichsen syndrome]].
|AnswerC=''Salmonella typhi''
|AnswerCExp=''[[Salmonella typhi]]'' causes [[typhoid fever]]. It is not associated with WFS.
|AnswerD=''Rickettsia prowazekii''
|AnswerDExp=''[[Rickettsia prowazekii]]'' causes [[endemic typhus]]. It is not associated with WFS.
|AnswerE=''Staphylococcus aureus''
|AnswerEExp=''[[Staphylococcus aureus]]'' causes staphylococcal scalded skin syndrome and [[toxic shock syndrome]]. Despite being associated with rare cases of WFS, it is not a major causative organism.
|EducationalObjectives=[[Waterhouse-Friderichsen syndrome]] is characterized by bilateral [[adrenal hemorrhage]] most commonly caused by ''[[Neisseria meningitidis]]'' septicemia.
|References=Warren HS, Gonzalez RG, Tian D. Case records of the Massachusetts General Hospital. Weekly clinicopathological exercises. Case 38-2003. A 12-year-old girl with fever and coma. N Engl J Med. 2003;349(24):2341-9.<br>
First Aid 2012 page 324
|RightAnswer=B
|WBRKeyword=Waterhouse-Friderichsen syndrome, Neisseria meningitidis, Neisseria, Sepsis, Adrenal insufficiency,
|Approved=Yes
}}