WBR0051

Author	PageAuthor::William J Gibson (Reviewed by Yazan Daaboul)
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::Genitourinary, SubCategory::General Principles, SubCategory::Infectious Disease
Prompt	[[Prompt::A 22-year-old woman presents to her primary care physician complaining of dysuria and mucopurulent urethral discharge for the past 3 days. She states that she had unprotected sexual encounter 2 weeks prior to presentation. Gram stain of the urethral swab reveals gram-negative diplococci. Which of the following media may be used to isolate organism causing this patient's condition?]]
Answer A	AnswerA::Thayer-Martin agar
Answer A Explanation	[[AnswerAExp::Neisseria gonorrhea is a gram-negative diploccocus whose infection constitutes the second most common sexually transmitted illness. Gonorrhea infection often presents as dysuria accompanied by purulent urethral discharge.]]
Answer B	AnswerB::MacConkey’s Agar
Answer B Explanation	[[AnswerBExp::MacConkey’s agar (MAC) is used to culture a variety of gram-negative organisms. Lactose-fermenting enterics (eg Escherichia coli) will appear as pink colonies.]]
Answer C	AnswerC::Tellurite Agar
Answer C Explanation	[[AnswerCExp::Tellurite agar may be use to culture Corynebacterium diptheriae.]]
Answer D	AnswerD::Bordet-Genou Agar
Answer D Explanation	[[AnswerDExp::Bordet-Genou agar is used to culture Bordetella pertussis.]]
Answer E	AnswerE::Sabouraud’s agar
Answer E Explanation	[[AnswerEExp::Sabouraud’s agar is used to culture fungi.]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::The patient in this vignette has been infected with Neisseria gonorrhea, a gram negative diplococcus. Neisseria gonorrhea is the second most common sexually transmitted infection after Chlamydia trachomatis. Because both organisms cause dysuria and urethral discharge, they may be difficult to differentiate without culture results. Nonetheless, ''N. gonorrhea'' is classically associated with a mucopurulent or purulent urethral discharge, Whereas Chlamydia trachomatis is associated with a more clear or mucoid discharge. N. gonorrhea may be cultured with Thayer-Martin media. Due to the high rate of co-infection when patients present with N. gonorrhea urethritis, proper treatment requires coverage for both N. gonorrhea and C. trachomatis using ceftriaxone and azithromycin to cover both organisms, respectively. Educational Objective: Neisseria gonorrhea is a sexually transmitted infection that often presents as dysuria accompanied by purulent urethral discharge. It grows on Thayer-Martin agar. Treatment consists of ceftriaxone to cover N. gonorrhea, along with azithromycin for concomitant coverage of a presumed Chlamydia trachomatis co-infection. References: First Aid 2014 page 137]]
Approved	Approved::Yes
Keyword	WBRKeyword::Sexually transmitted infection, WBRKeyword::STI, WBRKeyword::STD, WBRKeyword::Gonorrhea, WBRKeyword::Microbiology, WBRKeyword::Bacteria, WBRKeyword::Laboratory
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