WBR281
| Author | PageAuthor::Gerald Chi |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Microbiology, MainCategory::Pharmacology |
| Sub Category | SubCategory::Dermatology |
| Prompt | [[Prompt::A 55-year-old male comes to the clinic after being bitten by his wife. On examination, there is a 3-inch-long, deep puncture wound on his arm that is lined by human teeth marks. Cultures obtained at surgical debridement reveals growth of a fastidious, gram-negative facultative anaerobic bacillus. If antibiotic therapy is indicated, which of the following drugs should be used in this case?]] |
| Answer A | AnswerA::Cefazolin |
| Answer A Explanation | AnswerAExp::Incorrect - Agents lacking activity against Eikenella corrodens should generally be avoided. These include erythromycin, clindamycin, beta-lactamase-resistant penicillins, and first-generation cephalosporins. |
| Answer B | AnswerB::Dicloxacillin |
| Answer B Explanation | AnswerBExp::Incorrect - Agents lacking activity against Eikenella corrodens should generally be avoided. These include erythromycin, clindamycin, beta-lactamase-resistant penicillins, and first-generation cephalosporins. |
| Answer C | AnswerC::Erythromycin |
| Answer C Explanation | AnswerCExp::Incorrect - Agents lacking activity against Eikenella corrodens should generally be avoided. These include erythromycin, clindamycin, beta-lactamase-resistant penicillins, and first-generation cephalosporins. |
| Answer D | AnswerD::Clindamycin |
| Answer D Explanation | AnswerDExp::Incorrect - Agents lacking activity against Eikenella corrodens should generally be avoided. These include erythromycin, clindamycin, beta-lactamase-resistant penicillins, and first-generation cephalosporins. |
| Answer E | AnswerE::Amoxicillin-Clavulanate |
| Answer E Explanation | AnswerEExp::Correct - Amoxicillin-Clavulanate may be used as the primary regimen for human bite wounds caused by E. corrodens infeciton. |
| Right Answer | RightAnswer::E |
| Explanation | [[Explanation::E. corrodens is a pleomorphic bacillus that sometimes appears coccobacillary and typically creates a depression in the agar on which it is growing. It grows in aerobic and anaerobic conditions, but requires an atmosphere enhanced by 3–10% carbon dioxide. E. corrodens is a commensal of the human mouth and upper respiratory tract. It is an unusual cause of infection and when it is cultured, it is most usually found mixed with other organisms. Infections most commonly occur in patients with cancers of the head and neck, but it is also common in human bite infections, especially "reverse bite" or "fight bite", or "clenched fist injuries". It also causes infections in insulin-dependent diabetics and intravenous drug users who lick their needles ("needle-licker's osteomyelitis"). It is one of the HACEK group of infections which are a cause of culture-negative endocarditis. E. corrodens infections are typically indolent (the infection does not become clinically evident until a week or more after the injury). They also mimic anaerobic infection in being extremely foul-smelling. Educational Objective: |
| Approved | Approved::No |
| Keyword | WBRKeyword::Eikenella corrodens |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |