Internal Medicine Community-Acquired Pneumonia Questions and Answers — Questions and Answers
Question 1: A 67-year-old male with a history of COPD and type 2 diabetes presents to an outpatient clinic with a 3-day history of productive cough, fever, and dyspnea. He has not taken antibiotics in the past year. According to the 2019 IDSA/ATS guidelines, which of the following is the most appropriate empiric antibiotic regimen for this patient?
- Azithromycin monotherapy
- Amoxicillin monotherapy
- Amoxicillin-clavulanate plus doxycycline (Correct answer)
- Ciprofloxacin
Correct answer: Amoxicillin-clavulanate plus doxycycline
According to the 2019 IDSA/ATS guidelines, outpatients with community-acquired pneumonia (CAP) who have comorbidities (such as chronic lung disease or diabetes) should be treated with either combination therapy or monotherapy with a respiratory fluoroquinolone. [15] Combination therapy consists of a beta-lactam (like amoxicillin-clavulanate) PLUS a macrolide or doxycycline. [11, 15] Macrolide monotherapy is not recommended due to high rates of pneumococcal resistance. Amoxicillin monotherapy is an option for patients without comorbidities. Ciprofloxacin is not a respiratory fluoroquinolone and lacks reliable activity against *Streptococcus pneumoniae*.
Question 2: Which of the following clinical parameters is a component of the CURB-65 score for assessing the severity of community-acquired pneumonia?
- Oxygen saturation <92%
- A respiratory rate ≥ 30 breaths per minute (Correct answer)
- Multilobar infiltrates on chest x-ray
- Serum sodium < 130 mEq/L
Correct answer: A respiratory rate ≥ 30 breaths per minute
The CURB-65 score is an acronym for five clinical features used to predict mortality and determine the site of care for patients with CAP. One point is given for each of the following: Confusion (new onset), Urea > 7 mmol/L (BUN > 19 mg/dL), Respiratory rate ≥ 30 breaths/min, Blood pressure (systolic < 90 mmHg or diastolic ≤ 60 mmHg), and age ≥ 65 years. [1, 2, 6] The other options are indicators of severe pneumonia but are not components of the CURB-65 score.
Question 3: A 58-year-old female with no significant past medical history is admitted to a general medical ward for community-acquired pneumonia. She is hemodynamically stable, with an oxygen saturation of 94% on room air. Which of the following antibiotic regimens is the most appropriate initial empiric therapy?
- Vancomycin plus piperacillin-tazobactam
- Ceftriaxone plus azithromycin (Correct answer)
- Levofloxacin monotherapy
- Doxycycline monotherapy
Correct answer: Ceftriaxone plus azithromycin
For an adult with non-severe community-acquired pneumonia admitted to an inpatient ward, standard empiric therapy should cover both typical and atypical pathogens. The recommended primary regimen is a beta-lactam (e.g., ceftriaxone, ampicillin-sulbactam) combined with a macrolide (e.g., azithromycin). [16, 22] Monotherapy with a respiratory fluoroquinolone (e.g., levofloxacin) is an alternative. Vancomycin and piperacillin-tazobactam provide overly broad coverage for MRSA and Pseudomonas, which is not indicated without specific risk factors. Doxycycline monotherapy is typically reserved for outpatient treatment.
Question 4: A 62-year-old patient is admitted to the ICU with severe community-acquired pneumonia requiring mechanical ventilation. According to the 2019 IDSA/ATS guidelines, which of the following is the strongest indication to add empiric coverage for *Pseudomonas aeruginosa*?
- Recent hospitalization with receipt of parenteral antibiotics (Correct answer)
- Living in a nursing home
- History of alcoholism
- Admission to the ICU
Correct answer: Recent hospitalization with receipt of parenteral antibiotics
The 2019 IDSA/ATS guidelines recommend empiric treatment for *Pseudomonas aeruginosa* in patients with CAP only if locally validated risk factors are present. The most consistently cited major risk factors are prior respiratory isolation of *P. aeruginosa* or recent hospitalization (within 90 days) where the patient received parenteral antibiotics. [19, 21] While nursing home residence was part of the old HCAP definition, it is no longer considered a standalone indication. Alcoholism and ICU admission alone are not specific risk factors for *Pseudomonas*.
Question 5: A 70-year-old man presents with a 4-day history of high fever, a non-productive cough, watery diarrhea, and confusion. He is a retired plumber who recently worked on his home's hot water tank. Laboratory studies are notable for a serum sodium of 127 mEq/L. Which pathogen is the most likely cause of his pneumonia?
- Streptococcus pneumoniae
- Haemophilus influenzae
- Mycoplasma pneumoniae
- Legionella pneumophila (Correct answer)
Correct answer: Legionella pneumophila
The clinical presentation of pneumonia accompanied by prominent extrapulmonary symptoms, specifically gastrointestinal distress (diarrhea), neurologic symptoms (confusion), and hyponatremia, is highly characteristic of Legionnaires' disease, caused by *Legionella pneumophila*. [4, 20, 27] The exposure to a contaminated water source (hot water tank) further strengthens this diagnosis. While other pathogens can cause pneumonia, this specific constellation of findings is classic for *Legionella*.
Question 6: A 65-year-old patient is hospitalized for community-acquired pneumonia and has been receiving intravenous ceftriaxone and azithromycin for 72 hours. The patient's fever has resolved, heart rate is 85 bpm, blood pressure is 120/75 mmHg, and respiratory rate is 18 breaths/min. The patient is alert and has begun eating meals. Which of the following is the most appropriate next step in management?
- Continue IV antibiotics until the chest x-ray shows complete resolution of the infiltrate.
- Obtain a procalcitonin level to guide the duration of therapy.
- Switch to an equivalent oral antibiotic regimen. (Correct answer)
- Discharge the patient with a prescription for a 3-day course of IV antibiotics from a home infusion service.
Correct answer: Switch to an equivalent oral antibiotic regimen.
Clinical practice guidelines recommend switching from intravenous (IV) to oral antibiotics as soon as a patient is clinically stable and able to tolerate oral intake. [23, 25] Clinical stability is defined by parameters such as resolution of fever, hemodynamic stability (normal heart rate and blood pressure), and improving respiratory status. This patient meets the criteria for clinical stability. Waiting for radiographic resolution is not necessary, as imaging findings can lag behind clinical improvement for weeks. Transitioning to an appropriate oral regimen is the standard of care to facilitate hospital discharge and reduce complications associated with IV access. [17]
