WBR0945
| Author | [[PageAuthor::William J Gibson (Reviewed by Yazan Daaboul, M.D.)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Microbiology |
| Sub Category | SubCategory::Genitourinary |
| Prompt | [[Prompt::A sexually active 22-year-old woman presents to her primary care physician with complaints of burning sensation on urination for the past 2 days. Urine culture demonstrates colonies of catalase-positive, coagulase-negative, gram-positive cocci with novobiocin resistance. Which of the following pathogen's is most likely responsible for this patient's condition?]] |
| Answer A | AnswerA::''Escheria coli'' |
| Answer A Explanation | AnswerAExp::While ''E. coli'' is the leading cause of urinary tract infections among sexually active women, ''E.coli'' is a gram-negative rod. |
| Answer B | AnswerB::''Staphylococcus aureus'' |
| Answer B Explanation | AnswerBExp::While ''S. aureus'' is a catalase-positive, gram-positive coccus, it is coagulase-positive. |
| Answer C | AnswerC::''Staphylococcus epidermidis'' |
| Answer C Explanation | [[AnswerCExp::S. epidermidis is a catalase-positive, coagulase-negative, gram-positive coccus with novobiocin sensitivity. S. epidermidis is a component of the normal skin flora but can become pathogenic typically by infecting prosthetic devices. It is a common cause of endocarditis among patients with artificial valves.]] |
| Answer D | AnswerD::''Staphylococcus saprophyticus'' |
| Answer D Explanation | AnswerDExp::''S. Saprophyticus'' is a catalase-positive, coagulase-negative, gram-positive coccus with novobiocin resistance. It is the second most common cause of urinary tract infections among sexually active women, following ''E. coli''. |
| Answer E | AnswerE::''Streptococcus agalactiae'' |
| Answer E Explanation | AnswerEExp::''S agalactiae'' is a catalase-negative, beta-hemolytic, gram-positive coccus with bacitracin resistance. It is alternatively referred to as Group B streptococci and is a common cause of neonatal meningitis. |
| Right Answer | RightAnswer::D |
| Explanation | [[Explanation::The patient in this vignette has a urinary tract infection caused by Staphylococcus saprophyticus. S. saprophyticus is a catalase-positive, coagulase-negative, gram-positive coccus with novobiocin resistance. It is the second most common cause of urinary tract infections among sexually active women (10-20%) following E. coli. Educational Objective: S. Saprophyticus is a catalase-positive, coagulase-negative, gram-positive coccus with novobiocin resistance. It is the second most common cause of urinary tract infections among sexually active women. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Bacteria, WBRKeyword::Staphylococcus saprophyticus, WBRKeyword::Gram positive, WBRKeyword::Gram positive bacteria, WBRKeyword::UTI, WBRKeyword::Urinary tract infection, WBRKeyword::Laboratory classification, WBRKeyword::Catalase, WBRKeyword::Novobiocin, WBRKeyword::Coagulase |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |