WBR0062

Author	PageAuthor::William J Gibson
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology, MainCategory::Pharmacology
Sub Category	SubCategory::Dermatology, SubCategory::Infectious Disease
Prompt	[[Prompt::A 22 year old woman presents to your office. She developed the rash pictured below over the past four days. She describes it as extremely itchy but has applied some topical antihistamines and has experienced some relief. She reports no recent sick contacts, or contact with young children. She recalls having previously been infected with varicella zoster as a child. Two days ago, she returned from a vacation to South America where she stayed mostly at a resort where she and her friends had massages, swam, and enjoyed the hot tub. She denies using any new washing detergents nor any known allergies. What is the treatment of choice for the most likely causal organism?]]
Answer A	AnswerA::Acyclovir
Answer A Explanation	AnswerAExp::Incorrect - This is used to treat varicella zoster, which the woman has already been infected with and ought to be immune to.
Answer B	AnswerB::Piperacillin
Answer B Explanation	AnswerBExp::Correct - See Explanation
Answer C	AnswerC::Erythromycin
Answer C Explanation	AnswerCExp::Incorrect - Erythromycin is a macrolide antibiotic used to treat atypical pneumonias.
Answer D	AnswerD::Ciprofloxacin
Answer D Explanation	AnswerDExp::Incorrect - Ciprofloxacin is a fluoroquinolone antibiotic which blocks bacterial DNA topoisomerase. It is used primarily to treat UTIs and community acquired pneumonia.
Answer E	AnswerE::Ceftriaxone
Answer E Explanation	AnswerEExp::Incorrect - Ceftriaxone is a third generation cephalosporin which is also a beta-lactam based drug and inhibits cell wall synthesis. It is most commonly used against gram negative Neisseria Species.
Right Answer	RightAnswer::B
Explanation	[[Explanation::The patient in this vignette is presenting with a case of “hot tub folliculitis” caused by Pseudomonas Aeruginosa. A widespread, raised rash like the one seen in this patient should focus a differential between chicken pox, folliculitis and an allergic dermatitis. In this case, the patient’s history provides a clear clue by suggesting that the patient had been infected by pseudomonas while sitting in a hot tub. Pseudomonas aeruginosa is a gram negative rod which is oxidase positive. It is the cause of several water-bourne infections such as External otitis (swimmer’s ear) and hot tub folliculitis. Pseudomonas is known for producing a blue-green pigment called pyocyanin. The organism can also be identified by its distinct grape-like odor. Pseudomonal infections can be treated with aztreonam, or extended spectrum penicillins such as ticarcillin or piperacillin. Educational Objective: References: ]]
Approved	Approved::Yes
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