A 68-year-old man is admitted to the general medical floor with a 4-day history of fever, … — USMLE Step 2 CK

A $68$ -year-old man is admitted to the general medical floor with a $4$ -day history of fever, chills, and a cough productive of rust-colored sputum. His past medical history is significant only for benign prostatic hyperplasia. He has not had any recent hospitalizations, does not reside in a nursing facility, and has not received any antibiotics in the past year. Vital signs on presentation include a temperature of $38.8^{\circ}\text{C}$ ( $101.8^{\circ}\text{F}$ ), blood pressure of $115/76\text{ mm Hg}$ , pulse of $102/\text{min}$ , and respiratory rate of $24/\text{min}$ . Oxygen saturation is $94\%$ on $2\text{ L/min}$ via nasal cannula. Chest radiography demonstrates a dense consolidation in the left lower lobe. The admitting physician empirically prescribes intravenous piperacillin-tazobactam and vancomycin. A high-quality sputum Gram stain demonstrates many polymorphonuclear leukocytes and abundant Gram-positive diplococci. Which of the following is the most appropriate modification to this patient's antimicrobial regimen?

Switch to intravenous ceftriaxone and oral azithromycinCevap
B
Continue intravenous piperacillin-tazobactam and vancomycin
C
Switch to intravenous cefepime and intravenous levofloxacin
D
Discontinue vancomycin and continue intravenous piperacillin-tazobactam
E
Discontinue piperacillin-tazobactam and continue intravenous vancomycin

Cevap

Switch to intravenous ceftriaxone and oral azithromycin

This patient presents with a classic clinical picture of community-acquired pneumonia (CAP), highly likely due to Streptococcus pneumoniae given the rust-colored sputum and characteristic Gram-positive diplococci on Gram stain. Because he has no recent healthcare exposure, prior antibiotic use, or structural lung disease, he lacks risk factors for multidrug-resistant organisms such as methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa. Therefore, the empiric use of piperacillin-tazobactam and vancomycin in the emergency department was inappropriately broad. Principles of antibiotic stewardship dictate that therapy should be promptly de-escalated. The standard empiric treatment for a patient admitted to the medical ward for CAP is a beta-lactam (e.g., ceftriaxone, cefotaxime) combined with a macrolide (e.g., azithromycin) to cover both typical and atypical pathogens. Transitioning to this regimen provides optimal coverage while minimizing the risk of adverse drug events and antimicrobial resistance.

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Identify the primary clinical syndrome.

The patient's acute fever, productive cough, focal consolidation on radiography, and Gram-positive diplococci on sputum stain point to typical community-acquired pneumonia (CAP), most likely caused by Streptococcus pneumoniae.

Establishing the correct diagnosis guides the selection of empiric pharmacotherapy.

Assess the patient for risk factors for multidrug-resistant (MDR) organisms.

The patient resides in the community, has not been hospitalized recently, and has not received prior antibiotics, meaning he is at very low risk for Pseudomonas aeruginosa or methicillin-resistant Staphylococcus aureus (MRSA).

Risk stratification determines whether broad-spectrum antibiotics are warranted.

Evaluate the current therapeutic regimen against principles of antibiotic stewardship.

Piperacillin-tazobactam and vancomycin provide excessively broad coverage that is unwarranted for this patient, exposing him to unnecessary risks of toxicity and resistance.

Initial empiric regimens often need to be de-escalated once a patient's risk profile and preliminary data (like Gram stains) are reviewed.

Select the optimal standard regimen for inpatient CAP.

A beta-lactam (like ceftriaxone) combined with a macrolide (like azithromycin) provides appropriate coverage for typical pathogens (e.g., S. pneumoniae) and atypical pathogens (e.g., Mycoplasma, Legionella).

This combination represents standard-of-care empiric therapy for non-severe inpatient CAP without MDR risk factors.

Anahtar Kavram

Antibiotic stewardship in community-acquired pneumonia requires avoiding broad-spectrum agents targeting MRSA and Pseudomonas aeruginosa unless specific epidemiological risk factors are present, and instead utilizing targeted regimens like a beta-lactam plus a macrolide.

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