WBR0892
| Author | [[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Will Gibson)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Microbiology |
| Sub Category | SubCategory::Infectious Disease |
| Prompt | [[Prompt::A 25 year old male patient, previously healthy, is brought to the emergency department after a motor vehicle collision. The patient suffered extensive abdominal trauma and requires splenectomy and pancreatectomy. During post-operative care in the intensive care unit (ICU), the patient is started on intravenous hyperalimentation fluids. On day 10 of hyperalimentation, he develops fever and endophthalmitis. Blood cultures are taken immediately and empirical antimicrobial therapy is initiated. Which of the following organisms is most likely to responsible for this patient's condition?]] |
| Answer A | AnswerA::Pseudohyphae and budding yeast |
| Answer A Explanation | AnswerAExp::''Candida albicans'' are pseudohyphae and budding yeast. |
| Answer B | AnswerB::Irregular, broad, non-septate hyphae that branch at right angles |
| Answer B Explanation | AnswerBExp::''Rhizopus'' species are irregular, broad, non-septate hyphae that branch at right angles. |
| Answer C | AnswerC::Aerobic, oxidase-positive, gram-negative rods that produce pyocyanin |
| Answer C Explanation | AnswerCExp::''Pseudomonas aeroginosa'' is an aerobic, oxidase-positive, gram-negative rod that produces pyocyanin. |
| Answer D | AnswerD::Catalase-positive gram-positive cocci in clusters |
| Answer D Explanation | AnswerDExp::''Staphylococcus aureus'' is a catalase-positive gram-positive coccus in clusters. |
| Answer E | AnswerE::Gram-negative bacilli that form mucoid colonies |
| Answer E Explanation | AnswerEExp::''Klebsiella'' species are gam-negative bacilli that form mucoid colonies. |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::The patient is most likely suffering from Candida albicans infection, which is strongly associated with intravenous (IV) hyperalimentation. IV hyperalimentation is used to provide sufficient calories for patients who undergo extensive surgery, such as the patient described in the vignette. Approximately 15-20% of patients with IV hyperalimentation develop systemic candidiasis after several days of hyperalimentation. It is important to note that Candida is difficult to grow in culture media and more than 50% of cultures do not yield positive results. Because Candida may spread hematogenously to the eyes, endophthalmitis is commonly occurs. Educational Objective: Systemic candidiasis with Candida albicans is associated with IV hyperalimentation. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Candida albicans, WBRKeyword::Hyperalimentation, WBRKeyword::Intensive care unit, WBRKeyword::Pseudohyphae, WBRKeyword::Budding, WBRKeyword::Yeasts, WBRKeyword::Fungi, WBRKeyword::Fungal, WBRKeyword::Infection, WBRKeyword::Microbiology, WBRKeyword::Nosocomial |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |