WBR0473

Author	[[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Microbiology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::A 67 year old female patient presents to the emergency department for unremitting high grade fever and left leg pain. The patient explains that she had a left total knee replacement done 5 months ago. Following appropriate management, cultures reveal infection with a non-motile organism. Which of the following pathogens is the most likely cause of the patient's symptoms?]]
Answer A	AnswerA::Streptococcus bovis
Answer A Explanation	AnswerAExp::Streptococcus bovis is usually infectious in patients who are found to have colon cancer.
Answer B	AnswerB::Streptococcus pyogenes
Answer B Explanation	AnswerBExp::Streptococcus pyogenes commonly cause impetigo and pharyngitis. They are not classically associated with prosthetic infections following total knee replacement.
Answer C	AnswerC::Neisseria gonorrhea
Answer C Explanation	AnswerCExp::N. gonorrhea is a sexually transmitted infection that can cause infectious arthritis in sexually active individuals.
Answer D	AnswerD::Pseudomonas aeroginosa
Answer D Explanation	AnswerDExp::P. aeruginosa may be an infectious cause of a complicated total knee replacement. P. aeroginosa however is motile organism.
Answer E	AnswerE::Staphylococcus epidermidis
Answer E Explanation	AnswerEExp::S. epidermidis is commonly associated with infections following prosthetic implants.
Right Answer	RightAnswer::E
Explanation	[[Explanation::Staphylococcus epidermidis is a gram positive coagulase-negative non-motile organism that causes biofilms that grow on surgical implants or catheters. Hip and knee procedures, such as total knee replacement. Educational Objective: Staphylococcal epidermidis causes biofilms that bind to prosthetic surgical implants or catheters. References: First Aid 2014 page 130]]
Approved	Approved::Yes
Keyword	WBRKeyword::staphylococcus, WBRKeyword::epidermidis, WBRKeyword::total, WBRKeyword::knee, WBRKeyword::replacement, WBRKeyword::prosthesis, WBRKeyword::prosthetic, WBRKeyword::staphylococcus epidermidis, WBRKeyword::total knee replacement, WBRKeyword::gram, WBRKeyword::positive, WBRKeyword::organism, WBRKeyword::bacteria, WBRKeyword::infection, WBRKeyword::fever
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::