A previously healthy 35-year-old woman is brought into the emergency department after being found unresponsive by her husband. Her husband finds an empty bottle of diazepam tablets in her pocket. She is stuporous. At the hospital, her blood pressure is 90/40 mm Hg, the pulse is 58/min, and the respirations are 6/min. The examination of the pupils shows normal size and reactivity to light. Deep tendon reflexes are 1+ bilaterally. Babinski sign is absent. All 4 extremities are hypotonic. The patient is intubated and taken to the critical care unit for mechanical ventilation and treatment. Regarding the prevention of pneumonia in this patient, which of the following strategies is most likely to achieve this goal?

Subglottic drainage of secretions

Daily evaluation for ventilator weaning

Oropharynx and gut antibacterial decontamination

Prone positioning during mechanical ventilation

A 37-year-old man with a history of IV drug use presents to the ED with complaints of fevers, chills, and malaise for one week. He admits to recently using IV and intramuscular heroin. Vital signs are as follows: T 40.0 C, HR 120 bpm, BP 110/68 mmHg, RR 14, O2Sat 98%. Examination reveals a new systolic murmur that is loudest at the lower left sternal border. Initial management includes administration of which of the following regimens?

IV Vancomycin, IV ceftriaxone, IV fluconazole

IV Vancomycin, IV gentamicin, PO rifampin

A 42-year-old woman with a history of multiple sclerosis and recurrent urinary tract infections comes to the emergency department because of flank pain and fever. Her temperature is 38.8°C (101.8°F). Examination shows left-sided costovertebral angle tenderness. She is admitted to the hospital and started on intravenous vancomycin. Three days later, her symptoms have not improved. Urine culture shows growth of Enterococcus faecalis. Which of the following best describes the most likely mechanism of antibiotic resistance in this patient?

Alteration of peptidoglycan synthesis

Increased efflux across bacterial cell membranes

Alteration of penicillin-binding proteins

Alteration of ribosomal targets

A 27-year-old man presents to the emergency department for altered mental status. The patient was found napping in a local market and brought to the hospital. The patient has a past medical history of polysubstance abuse and is homeless. His temperature is 104°F (40.0°C), blood pressure is 100/52 mmHg, pulse is 133/min, respirations are 25/min, and oxygen saturation is 99% on room air. Physical exam is notable for an altered man. Cardiopulmonary exam reveals a murmur over the left lower sternal border. A bedside ultrasound reveals a vegetation on the tricuspid valve. The patient is ultimately started on IV fluids, norepinephrine, vasopressin, vancomycin, and piperacillin-tazobactam. A central line is immediately placed in the internal jugular vein and the femoral vein secondary to poor IV access. Cardiothoracic surgery subsequently intervenes to remove the vegetation. While recovering in the ICU, days 3-5 are notable for an improvement in the patient’s symptoms. Two additional peripheral IVs are placed while in the ICU on day 5, and the femoral line is removed. On day 6, the patient's fever and hemodynamic status worsen. Though he is currently responding and not complaining of any symptoms including headache, photophobia, neck stiffness, or pain, he states he is feeling weak. Jolt accentuation of headache is negative and his abdominal exam is benign. A chest radiograph, urinalysis, and echocardiogram are unremarkable though the patient’s blood cultures are positive when drawn. Which of the following is the best next step in management?

Remove the central line and send for cultures

Add micafungin to the patient’s antibiotics

Remove all peripheral IV’s and send for cultures

Add cefepime to the patient’s antibiotics

A 59-year-old woman comes to the emergency department because of a 2-day history of worsening fever, chills, malaise, productive cough, and difficulty breathing. Three days ago, she returned from a trip to South Africa. She has type 2 diabetes mellitus, hypertension, and varicose veins. Her current medications include metformin, lisinopril, and atorvastatin. Her temperature is 39.4°C (102.9°F), pulse is 102/minute, blood pressure is 94/68 mm Hg, and respirations are 31/minute. Pulse oximetry on 2 L of oxygen via nasal cannula shows an oxygen saturation of 91%. Examination reveals decreased breath sounds and dull percussion over the left lung base. The skin is very warm and well-perfused. The remainder of the examination shows no abnormalities. Laboratory studies show: Hemoglobin 11.6 g/dL Leukocyte count 15,400/mm3 platelet count 282,000/mm3 Serum Na+ 144 mEq/L Cl- 104 mEq/L K+ 4.9 mEq/L Creatinine 1.5 mg/dL Blood and urine for cultures are obtained. Intravenous fluid resuscitation is begun. Which of the following is the next best step in management?

Intravenous ceftriaxone and azithromycin

External cooling and intravenous acetaminophen

Intravenous vancomycin and ceftriaxone

A 50-year-old man with a history of stage 4 kidney disease was admitted to the hospital for an elective hemicolectomy. His past medical history is significant for severe diverticulitis. After the procedure he becomes septic and was placed on broad spectrum antibiotics. On morning rounds, he appear weak and complains of fatigue and nausea. His words are soft and he has difficulty answering questions. His temperature is 38.9°C (102.1°F), heart rate is 110/min, respiratory rate is 15/min, blood pressure 90/65 mm Hg, and saturation is 89% on room air. On physical exam, his mental status appears altered. He has a bruise on his left arm that spontaneously appeared overnight. His cardiac exam is positive for a weak friction rub. Blood specimens are collected and sent for evaluation. An ECG is performed (see image). What therapy will this patient most likely receive next?

Send the patient for hemodialysis

Perform a STAT pericardiocentesis

Prepare the patient for renal transplant

Treat the patient with cyclophosphamide and prednisone

Five days after admission into the ICU for drug-induced acute kidney injury, a 27-year-old woman develops fever. She is currently on a ventilator and sedatives. Hemodialysis is performed via a catheter placed in the right internal jugular vein. Feeding is via a nasogastric tube. An indwelling urinary catheter shows minimum output. Her blood pressure is 85/45 mm Hg, the pulse is 112/min, the respirations are 32/min, and the temperature is 39.6°C (103.3°F). The examination of the central catheter shows erythema around the insertion site with no discharge. Lung auscultation shows rhonchi. Cardiac examination shows no new findings. A chest CT scan shows bilateral pleural effusions with no lung infiltration. Empirical antibiotic therapy is initiated. Blood cultures obtained from peripheral blood and the catheter tip show S. aureus with a similar antibiogram. Urinary culture obtained from the indwelling catheter shows polymicrobial growth. Which of the following best explains this patient’s recent findings?

Central catheter-related bacteremia

Catheter-associated urinary tract infection

Ventilator-associated pneumonia

Antimicrobial stewardship for USMLE Step 1: High-Yield Internal Medicine Lessons

AMS Fundamentals - The Right Drug, Dose, Duration

Right Drug: Base empiric choices on local antibiogram. De-escalate to the narrowest effective agent based on culture results.
Right Dose: Optimize using pharmacokinetics/pharmacodynamics (PK/PD).
- Time-dependent (e.g., β-lactams): More frequent dosing or prolonged infusions.
- Concentration-dependent (e.g., aminoglycosides): Higher doses, less frequent intervals.
- Adjust for renal and hepatic function.
Right Duration: Use the shortest effective course. Procalcitonin can help guide cessation for respiratory tract infections.

⭐ A cornerstone of AMS is de-escalation: narrowing antibiotic spectrum and/or switching from IV to an equivalent oral agent once the patient is clinically stable. This reduces selective pressure for resistance.

Hospital Antibiogram Chart: Susceptibility Data

Sepsis Stewardship - Hit Hard, Then Focus

Initial Management (Hour-1 Bundle): Act fast. Upon suspicion of sepsis (e.g., qSOFA ≥2), immediately draw blood cultures, administer broad-spectrum antibiotics, measure lactate, and begin fluid resuscitation (30 mL/kg crystalloid for hypotension).
De-escalation Principle: The cornerstone of sepsis stewardship. Re-evaluate therapy at 48-72 hours.
- Narrow antibiotic coverage based on culture and sensitivity results.
- Stop antibiotics if infection is unlikely.

⭐ Procalcitonin (PCT) levels can guide antibiotic de-escalation. A significant drop (>80% from peak) supports stopping antibiotics, reducing duration and resistance risk.

Endocarditis Endgame - Target the Tiny Terrors

Core Goal: Prolonged, bactericidal, IV therapy tailored to the specific pathogen. Stewardship focuses on narrowing therapy once sensitivities are known.
Culture is Critical: Always obtain ≥3 sets of blood cultures before starting empiric antibiotics. Diagnosis relies on modified Duke Criteria.
Common Pathogens & De-escalation Targets:
- S. aureus: Nafcillin/Oxacillin (MSSA); Vancomycin (MRSA).
- Viridans Streptococci: Penicillin G or Ceftriaxone.
- Enterococcus: Ampicillin + Gentamicin (synergy).
- S. gallolyticus (bovis): See below!
Therapy Duration: Typically 4-6 weeks. Monitor for drug toxicity (e.g., aminoglycoside nephrotoxicity) and clinical response.

⭐ Streptococcus gallolyticus endocarditis warrants a colonoscopy to screen for underlying colorectal cancer.

📌 FROM JANE: Fever, Roth spots, Osler nodes, Murmur, Janeway lesions, Anemia, Nail-bed hemorrhage, Emboli.

Transesophageal echocardiogram of aortic valve vegetation

The Stewardship Toolkit - Measure What You Manage

Core Principle: Track both processes & outcomes to demonstrate value and guide interventions.
Process Measures (The "How"):
- Adherence to local/national guidelines.
- Antibiotic "timeout" completion rates at 48-72 hrs.
- Formulary restriction & pre-authorization compliance.
Outcome Measures (The "What"):
- Financial: ↓ Antimicrobial acquisition costs.
- Microbiological: ↓ Rates of C. difficile, MRSA, VRE.
- Utilization Metrics: Days of Therapy (DOT), Defined Daily Doses (DDD).

⭐ A key success marker for stewardship programs is a significant reduction in hospital-onset Clostridioides difficile infection (CDI) rates.

High‑Yield Points - ⚡ Biggest Takeaways

Sepsis management hinges on early recognition, prompt broad-spectrum antibiotics after blood cultures, and aggressive fluid resuscitation.

Infective Endocarditis diagnosis relies on Duke criteria; empiric treatment often involves vancomycin to cover Staph/Strep.

Antimicrobial stewardship focuses on the 4 D's: right Drug, Dose, Duration, and crucial De-escalation.

De-escalation based on culture sensitivities is key to minimizing resistance.

Procalcitonin (PCT) levels can guide stopping antibiotics, particularly in sepsis.

Always prioritize source control (e.g., draining abscesses, removing infected lines).

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