All practice questions

A 67-year-old man is hospitalized in the intensive care unit for ventilator-associated pneumonia. Initial endotracheal aspirate cultures grow *Pseudomonas aeruginosa* that is susceptible to piperacillin-tazobactam, cefepime, ciprofloxacin, and imipenem. The patient is started on intravenous imipenem-cilastatin. He initially improves, but on day 11 of hospitalization, his respiratory status declines, and he requires an increase in ventilator support. His temperature is 38.9°C (102°F), blood pressure is 100/60 mm Hg, and pulse is 110/min. A repeat endotracheal aspirate culture again grows *Pseudomonas aeruginosa*. Susceptibility testing of the new isolate reveals resistance to imipenem, but continued susceptibility to cefepime, piperacillin-tazobactam, and ciprofloxacin. Which of the following is the most likely mechanism for the rapid emergence of antimicrobial resistance in this patient's infection?

Match each clinical scenario of antimicrobial treatment failure with the primary molecular or cellular mechanism responsible for the pathogen's resistance.

A 23-year-old woman presents to the outpatient clinic with a 3-day history of swelling and a dull ache in her left calf. Her medical history is unremarkable, and she takes no medications other than an oral contraceptive pill that she started three months ago. Vital signs are within normal limits. Physical examination reveals a 3-cm increase in the circumference of the left calf compared to the right, along with localized tenderness along the deep venous system. A comprehensive metabolic panel and complete blood count are within normal limits. Doppler ultrasound confirms an occlusive thrombus in the left popliteal vein. Family history reveals that her maternal aunt developed a pulmonary embolism at age 30 during her first pregnancy. Which of the following best describes the underlying pathophysiologic mechanism of this patient's most likely condition?

A 58-year-old man is admitted to the medical ward with a 3-week history of progressive lethargy, confusion, polyuria, and constipation. Medical history is significant for essential hypertension and a 30-pack-year smoking history. Current medications include amlodipine and lisinopril. Vital signs are within normal limits. Physical examination reveals a lethargic man with dry mucous membranes but is otherwise unremarkable.

Based on the preliminary laboratory evaluation, the physician is revisiting the patient's medical, social, and occupational history to narrow the differential diagnosis. Which of the following historical elements are the MOST critical to specifically query to elucidate the primary etiology of this patient's hypercalcemia? (Select all that apply)

A 45-year-old woman is brought to the emergency department by her husband due to a severe headache, confusion, and a witnessed generalized tonic-clonic seizure. She has a history of poorly controlled hypertension and medication non-adherence. On arrival, her blood pressure is 225/125 mm Hg, heart rate is 105/min, and respiratory rate is 18/min. She is postictal and somnolent.

After initial airway protection, an expedited MRI of the brain is performed due to the institution's stroke protocol. The MRI demonstrates the following specific findings:
- T2-weighted and fluid-attenuated inversion recovery (FLAIR) sequences show symmetric, bilateral, confluent areas of hyperintensity in the subcortical white matter of the parietal and occipital lobes.
- Diffusion-weighted imaging (DWI) shows iso-intensity to mild hyperintensity in the corresponding regions.
- Apparent diffusion coefficient (ADC) mapping reveals marked hyperintensity in these same parieto-occipital areas.

Based on the interpretation of these imaging results, which of the following is the most appropriate next step in management?

Match the following classic ocular and pupillary physical examination findings with their most likely underlying etiology or clinical condition.

Match the following molecular or genetic lesions with their corresponding classic clinical and laboratory phenotype.

A $54$-year-old man is admitted to the intensive care unit with a severe bloodstream infection caused by *Pseudomonas aeruginosa*. He is to be started on an intravenous aminoglycoside. The patient weighs $80$ kg. His estimated volume of distribution for the drug is $0.25$ L/kg.

To ensure optimal bactericidal activity and minimize the risk of acute tubular necrosis, the clinical pharmacist recommends targeting a steady-state peak serum concentration of $8.0$ mg/L and a steady-state trough serum concentration of $2.0$ mg/L. Based on the patient's current renal function, the elimination half-life of the drug is determined to be $8$ hours.

Assuming the drug follows a one-compartment pharmacokinetic model and distributes instantaneously, what maintenance dose (in mg) must be administered at each dosing interval to achieve these exact steady-state target concentrations?

A 42-year-old woman comes to the primary care clinic complaining of progressive fatigue, weakness, and dyspnea on exertion over the past 3 months. She also reports a recent, strong craving to chew ice. Her medical history is unremarkable, and she takes no medications. She reports having heavy menstrual periods that last 7 to 8 days each month. Vital signs are within normal limits. Physical examination reveals noticeable pallor of the conjunctivae. Which of the following is the most appropriate initial laboratory evaluation to order for this patient?

A 55-year-old woman with a recently diagnosed right-sided breast carcinoma undergoes a lumpectomy followed by adjuvant external beam radiation therapy. The primary therapeutic effect of the ionizing radiation on residual neoplastic cells relies on the generation of reactive oxygen species and the direct induction of double-strand DNA breaks, which ultimately trigger programmed cell death.

Arrange the following subcellular events in the correct chronological order to accurately describe the intrinsic apoptotic cascade that leads to the death of these malignant cells.

Match each patient's clinical presentation and laboratory profile with the most likely underlying coagulation disorder.

A 61-year-old woman is evaluated in the emergency department for the sudden onset of severe, continuous room-spinning dizziness that began 6 hours ago. The dizziness is present even when she is perfectly still, but it is severely exacerbated by any head movement. She also reports intractable nausea and two episodes of vomiting. Her medical history includes hypertension and hyperlipidemia. Her blood pressure is 154/90 mm Hg, and her pulse is 88/min. She is unable to walk without assistance. On physical examination, the patient is awake and alert. Oculomotor examination reveals spontaneous, horizontal-torsional nystagmus that beats toward the left; the nystagmus increases in amplitude when she looks to the left but does not change direction when she looks to the right. The examiner asks the patient to fixate on a target and rapidly rotates her head to the right; a corrective saccade is observed as her eyes snap back to the target. Rapid head rotation to the left produces no corrective saccade. An alternate cover test reveals no vertical misalignment of the eyes. Otoscopic and hearing examinations are unremarkable. A basic metabolic panel shows a serum sodium of 133 mEq/L and potassium of 3.8 mEq/L. Which of the following is the most appropriate diagnostic interpretation and next step in management based on these physical examination findings?

Match each clinical finding regarding the diagnostic evaluation of a newly discovered thyroid nodule with the most appropriate guideline-indicated next step in management.

Match each eponymous abdominal physical examination sign with its precise underlying anatomical and pathophysiological mechanism.

A 24-year-old man comes to the clinic for a routine health maintenance examination and sexually transmitted infection screening. He reports having a new male sexual partner for the past month and admits to inconsistent condom use. He has no fever, rash, weight loss, or lymphadenopathy. His physical examination is entirely unremarkable. The physician decides to evaluate him for HIV.

Arrange the following laboratory tests in the correct sequential order for diagnosing and establishing a baseline evaluation for HIV, assuming the initial screening and subsequent confirmatory diagnostic tests yield reactive or positive results.

A 52-year-old woman is evaluated in the outpatient clinic for persistently elevated blood pressure. Over the past six months, her blood pressure has remained uncontrolled despite reported adherence to a regimen of amlodipine, lisinopril, and chlorthalidone. She complains of generalized weakness, intermittent muscle cramps in her calves, and mild fatigue. Her medical history includes osteoarthritis, seasonal allergic rhinitis, and mild, chronic dyspepsia. She has no prior surgeries. She does not smoke or drink alcohol, follows a standard diet, and walks 30 minutes daily. Her current prescription medications include her antihypertensives, and she frequently takes over-the-counter pain relievers and oral decongestants. Her temperature is 37.0°C (98.6°F), blood pressure is 168/98 mm Hg, and pulse is 76/min. Physical examination reveals no peripheral edema, abdominal bruits, or abnormal facies.

Laboratory studies show:

Further targeted history-gathering regarding which of the following areas is most critical to establishing the diagnosis in this patient?

A 58-year-old woman is brought to the emergency department via ambulance after experiencing 45 minutes of crushing, substernal chest pain radiating to her left jaw. An electrocardiogram reveals ST-segment elevations in leads V1 through V4. She is rapidly taken to the cardiac catheterization laboratory, where a thrombotic occlusion of the left anterior descending artery is identified. Percutaneous coronary intervention (PCI) is performed, successfully restoring TIMI 3 flow. Over the next several hours, her serum troponin levels peak dramatically higher than expected for the infarct size, and she develops transient arrhythmias. The physician suspects that the restoration of blood flow has paradoxically exacerbated local cellular injury in the border zone of the infarct. Arrange the following subcellular and biochemical events in the correct chronological sequence that mediates this specific type of iatrogenic myocardial damage.

A 47-year-old woman is evaluated in the infectious disease clinic for treatment of a refractory systemic fungal infection following a recent hematopoietic stem cell transplant. She is currently taking tacrolimus and prophylactic acyclovir. The physician plans to start an oral formulation of a novel triazole antifungal agent. The patient's current body weight is $75 \text{ kg}$. According to the pharmacokinetic profile of this new medication, it has an oral bioavailability ($F$) of $50\%$, a volume of distribution ($V_d$) of $2.0 \text{ L/kg}$, and a systemic clearance ($Cl$) of $0.04 \text{ L/hr/kg}$. The therapeutic goal is to maintain an average steady-state plasma concentration ($C_{ss,avg}$) of $15 \text{ mg/L}$. The dosing regimen will consist of administration every 8 hours.

What is the required oral dose in milligrams ($\text{mg}$) to be given every 8 hours to achieve the target steady-state concentration?

A 68-year-old man with a history of hypertension and hyperlipidemia is brought to the emergency department 2 hours after the onset of severe, crushing substernal chest pain. An electrocardiogram reveals prominent ST-segment elevations in leads V1 through V4. He is immediately transferred to the cardiac catheterization laboratory, where a completely occluded proximal left anterior descending artery is identified and successfully opened with a drug-eluting stent. Despite the successful restoration of blood flow and complete resolution of his chest pain, his serum troponin levels exhibit an unexpectedly massive spike four hours post-procedure, accompanied by frequent premature ventricular contractions. Which of the following subcellular processes is the primary mediator of the paradoxical myocardial damage observed following the restoration of perfusion in this patient?

A 42-year-old recent immigrant from Southeast Asia presents to the outpatient clinic with a 6-week history of low-grade fever, drenching night sweats, chronic cough with blood-tinged sputum, and a 5-kg (11-lb) unintentional weight loss. A chest radiograph demonstrates a cavitary lesion in the right upper lobe. Sputum smear is positive for acid-fast bacilli. The patient is initiated on standard quadruple antimicrobial therapy. Several weeks later, the state health department reports that the isolated organism is resistant to the agent within the regimen that primarily inhibits mycolic acid synthesis. Which of the following is the most likely molecular mechanism responsible for this specific drug resistance?