ABEM Toxicology, Environmental & Infectious Diseases 2 — Questions and Answers
Question 1: A patient presents with bradycardia, hypotension, and hyperkalemia after ingesting a large quantity of sustained-release verapamil. Which antidote provides the most direct physiologic benefit?
- Calcium gluconate IV
- Glucagon IV
- Lipid emulsion therapy
- High-dose insulin with dextrose (Correct answer)
Correct answer: High-dose insulin with dextrose
High-dose insulin euglycemic therapy (HIET) improves myocardial carbohydrate metabolism and is the mainstay treatment for severe calcium channel blocker overdose.
Question 2: A hiker returns from the Appalachian Trail with fever, headache, and a petechial rash spreading centripetally from the wrists and ankles. What is the treatment of choice?
- Azithromycin
- Doxycycline (Correct answer)
- Ceftriaxone
- Amoxicillin-clavulanate
Correct answer: Doxycycline
Doxycycline is the drug of choice for Rocky Mountain Spotted Fever (Rickettsia rickettsii) in all age groups, including children.
Question 3: Which of the following is the MOST reliable antidote for methanol poisoning in the emergency setting when fomepizole is unavailable?
- N-acetylcysteine
- Ethanol IV infusion (Correct answer)
- Sodium bicarbonate bolus
- Pyridoxine IV
Correct answer: Ethanol IV infusion
Ethanol competitively inhibits alcohol dehydrogenase and prevents conversion of methanol to its toxic metabolite formic acid when fomepizole is unavailable.
Question 4: A 22-year-old is brought in with hyperthermia of 41.2°C, muscle rigidity, diaphoresis, and clonus after starting linezolid while taking sertraline. Which intervention is MOST important to reduce mortality?
- Dantrolene 2.5 mg/kg IV
- Lorazepam 2 mg IV and active cooling (Correct answer)
- Cyproheptadine 12 mg PO
- Bromocriptine 2.5 mg PO
Correct answer: Lorazepam 2 mg IV and active cooling
Serotonin syndrome treatment prioritizes benzodiazepines for neuromuscular agitation plus aggressive cooling; cyproheptadine is adjunctive but oral delivery is slower.
Question 5: A patient presents with respiratory failure, miosis, bradycardia, and excessive secretions after a farmworker exposure. What is the appropriate initial dose of atropine?
- 0.5 mg IV, titrate slowly
- 2–4 mg IV, repeat every 5–10 min until secretions dry (Correct answer)
- 10 mg IV single bolus
- 0.04 mg/kg IM as a single dose
Correct answer: 2–4 mg IV, repeat every 5–10 min until secretions dry
Organophosphate poisoning requires aggressive atropinization starting at 2–4 mg IV titrated to drying of secretions, which is the clinical endpoint.
Question 6: Which of the following correctly characterizes the Rumack-Matthew nomogram used in acetaminophen toxicity?
- It applies to all acetaminophen exposures regardless of time of ingestion
- It predicts hepatotoxicity risk based on serum level plotted against time post-ingestion (Correct answer)
- It is used to determine NAC dosing duration
- It is valid for extended-release acetaminophen formulations
Correct answer: It predicts hepatotoxicity risk based on serum level plotted against time post-ingestion
The Rumack-Matthew nomogram plots serum acetaminophen concentration against hours post-acute ingestion to predict risk of hepatotoxicity and guide NAC treatment.
Question 7: A patient presents with fever, neck stiffness, and photophobia. CSF shows glucose 30 mg/dL, protein 180 mg/dL, and 800 WBC/µL (90% neutrophils). Which empiric antibiotic regimen is most appropriate for an immunocompetent adult?
- Vancomycin + ceftriaxone + ampicillin
- Vancomycin + ceftriaxone + dexamethasone (Correct answer)
- Ceftriaxone alone
- Meropenem + vancomycin
Correct answer: Vancomycin + ceftriaxone + dexamethasone
Bacterial meningitis in an immunocompetent adult is treated with vancomycin plus a third-generation cephalosporin; dexamethasone reduces inflammation and improves outcomes, particularly in S. pneumoniae meningitis.
