WBR0051

Author	PageAuthor::William J Gibson
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 for the past 3 days with mild urethral discharge. Her last unprotected sexual encounter was 2 weeks ago. Gram stain of the urethral swab reveals gram-negative diplococci. Which of the following media could be used to isolate this organism?]]
Answer A	AnswerA::Thayer-Martin
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 discharge.]]
Answer B	AnswerB::Maconkey’s Agar
Answer B Explanation	[[AnswerBExp::Maconkey’s agar is used to culture a variety of organisms. Lactose-fermenting enterics (eg Escherichia coli) will appear as pink colonies.]]
Answer C	AnswerC::Tellurite Agar
Answer C Explanation	[[AnswerCExp::Tellurite agar can be use to culture Corynebacterium diptheria.]]
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 illness behind chlamydia. Because both organisms cause dysuria and discharge, they are hard to differentiate without culture results. Whereas Chlamydia trachomatis is usually detected with nucleic acid based assays, Neisseria gonorrhea can be cultured with Thayer-Martin media. Due to the high rate of co-infection and clinical difficulty in distinguishing the two organisms, proper treatment requires ceftriaxone (for gonorrhea coverage) and azithromycin (for chlamydia coverage). Educational Objective: Gonorrhea infection often presents as dysuria accompanied by purulent discharge. References: First Aid 2014 page 137 http://www.cdc.gov/nchhstp/newsroom/docs/STD-Trends-508.pdf]]
Approved	Approved::Yes
Keyword	WBRKeyword::Sexually transmitted infection, WBRKeyword::STI, WBRKeyword::STD, WBRKeyword::Gonorrhea, WBRKeyword::Microbiology, WBRKeyword::Bacteria, WBRKeyword::Laboratory
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::