WBR0712

Author	PageAuthor::William J Gibson (Reviewed by Serge Korjian)
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::Endocrine, SubCategory::Infectious Disease
Prompt	[[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 causal organism?]]
Answer A	AnswerA::''Listeria monocytogenes''
Answer A Explanation	[[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.]]
Answer B	AnswerB::''Neisseria meningitidis''
Answer B Explanation	[[AnswerBExp::Neisseria meningitidis is the classical cause of Waterhouse–Friderichsen syndrome.]]
Answer C	AnswerC::''Salmonella typhi''
Answer C Explanation	[[AnswerCExp::Salmonella typhi causes typhoid fever. It is not associated with WFS.]]
Answer D	AnswerD::''Rickettsia prowazekii''
Answer D Explanation	[[AnswerDExp::Rickettsia prowazekii causes endemic typhus. It is not associated with WFS.]]
Answer E	AnswerE::''Staphylococcus aureus''
Answer E Explanation	[[AnswerEExp::Staphylococcus aureus causes staph scalded skin syndrome and toxic shock syndrome. Despite being associated with rare cases of WFS, it is not a major causative organism.]]
Right Answer	RightAnswer::B
Explanation	[[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. Educational Objective: Waterhouse-Friderichsen syndrome is characterized by bilateral adrenal hemorrhage most commonly caused by Neisseria meningitidis septicemia. References: Harris, P., & Bennett, A. (2001). Waterhouse-Friderichsen syndrome. N Engl J Med, 345(11), 841. First Aid 2012 page 324]]
Approved	Approved::Yes
Keyword	WBRKeyword::Waterhouse-Friderichsen syndrome, WBRKeyword::Neisseria meningitidis, WBRKeyword::Neisseria, WBRKeyword::Sepsis, WBRKeyword::Adrenal insufficiency
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