All questions
Question 1
A 72-year-old man with a history of COPD, type 2 diabetes mellitus, and coronary artery disease is brought to the emergency department with a 3-day history of worsening shortness of breath, productive cough, and fever. His temperature is 38.9°C (102.0°F), blood pressure is 105/65 mm Hg, heart rate is 115/min, and respiratory rate is 28/min. His oxygen saturation is 89% on room air. A chest x-ray reveals a left lower lobe infiltrate. He is admitted to the general medical ward.
Which of the following is the most appropriate empiric antibiotic regimen for this patient?
- Doxycycline
- Ceftriaxone and azithromycin (correct answer)
- Piperacillin-tazobactam and vancomycin
- Amoxicillin-clavulanate
Explanation: This patient has community-acquired pneumonia requiring inpatient admission. He has multiple comorbidities (COPD, diabetes). The standard of care for non-severe inpatient CAP is a combination of a beta-lactam (e.g., ceftriaxone) plus a macrolide (e.g., azithromycin), or monotherapy with a respiratory fluoroquinolone (e.g., levofloxacin). This regimen provides coverage for typical pathogens like Streptococcus pneumoniae as well as atypical pathogens.
Question 2
A 65-year-old man presents with a 5-day history of fever, cough, and shortness of breath. He also reports headache, myalgias, and watery diarrhea. His medical history is notable for smoking. He recently returned from a convention where he stayed in a large hotel. Laboratory studies show a sodium level of 128 mEq/L. A chest x-ray shows patchy, unilateral lower lobe infiltrates.
Which of the following diagnostic tests is most likely to confirm the diagnosis?
- Sputum Gram stain and culture
- Blood cultures
- Urine antigen test (correct answer)
- Serum cold agglutinin test
Explanation: This patient's presentation with pneumonia accompanied by gastrointestinal symptoms (diarrhea), neurologic symptoms (headache), and hyponatremia, in the context of a recent hotel stay, is classic for Legionnaires' disease, caused by Legionella pneumophila. The most rapid and specific diagnostic test is the urine antigen test for L. pneumophila serogroup 1.
Question 3
A 62-year-old woman is being treated for community-acquired pneumonia with intravenous ceftriaxone and azithromycin. Despite 5 days of therapy, she remains febrile with a persistent cough. A repeat chest x-ray shows the initial infiltrate and a new, large, loculated pleural effusion. A diagnostic thoracentesis is performed. The pleural fluid is purulent, with a pH of 7.0, glucose of 30 mg/dL, and LDH >1000 U/L. Gram stain shows gram-positive cocci in chains.
In addition to continuing appropriate antibiotic therapy, which of the following is the most appropriate next step in management?
- Repeat thoracentesis in 48 hours
- Chest tube placement (correct answer)
- Surgical decortication
- Observation with current antibiotics
Explanation: This patient has an empyema, which is a complicated parapneumonic effusion characterized by the presence of pus or bacteria in the pleural space. The pleural fluid analysis (pH < 7.2, glucose < 60 mg/dL, positive Gram stain) confirms this. The definitive management for an empyema requires drainage of the infected fluid in addition to antibiotics. The first-line intervention for drainage is the placement of a chest tube (tube thoracostomy).
Question 4
A 50-year-old man is being treated for active pulmonary tuberculosis with a standard four-drug regimen. Six weeks into therapy, he presents for a follow-up visit and complains of decreased visual acuity and difficulty distinguishing between the colors red and green.
Which of the following medications is most likely responsible for his symptoms?
- Isoniazid
- Rifampin
- Pyrazinamide
- Ethambutol (correct answer)
Explanation: Optic neuritis, characterized by decreased visual acuity, central scotoma, and color blindness (especially red-green), is a well-known, dose-dependent adverse effect of ethambutol. This is a reversible condition if the drug is discontinued promptly. Patients starting ethambutol should have a baseline vision screen and be counseled to report any visual changes immediately.
Question 5
A 19-year-old college student living in a dormitory presents with a 2-week history of a persistent dry cough, headache, and low-grade fever. She says several of her friends in the dorm have had a similar illness. On examination, she is afebrile and in no acute distress. Lung auscultation is clear. A chest x-ray reveals bilateral, patchy interstitial infiltrates.
Which of the following is the most likely causative organism?
- Streptococcus pneumoniae
- Mycoplasma pneumoniae (correct answer)
- Klebsiella pneumoniae
- Staphylococcus aureus
Explanation: This patient's subacute presentation, age, and setting (college dormitory) are classic for an atypical pneumonia, often referred to as 'walking pneumonia.' Mycoplasma pneumoniae is the most common cause of atypical pneumonia in young, healthy adults. The indolent course, non-productive cough, and interstitial pattern on chest x-ray are characteristic features.
Question 6
A 55-year-old man with community-acquired pneumonia is admitted to the intensive care unit due to septic shock requiring vasopressor support. His medical history is significant for alcoholism. He has no known drug allergies. Sputum Gram stain shows numerous neutrophils and gram-positive cocci in pairs and chains.
Which of the following is the most appropriate initial intravenous antibiotic regimen?
- Ampicillin-sulbactam
- Ceftriaxone and azithromycin (correct answer)
- Levofloxacin
- Doxycycline
Explanation: This patient has severe community-acquired pneumonia, as evidenced by his need for ICU admission and vasopressor support for septic shock. Guidelines for severe CAP recommend a combination of a beta-lactam (e.g., ceftriaxone) plus a macrolide (e.g., azithromycin) or a beta-lactam plus a respiratory fluoroquinolone. This combination provides broad coverage against the most likely pathogen, Streptococcus pneumoniae (suggested by the Gram stain), as well as atypical pathogens.
Question 7
A 65-year-old man is on mechanical ventilation in the ICU for 8 days following a severe gastrointestinal bleed. He develops a new fever to 39.0°C (102.2°F), an increase in purulent endotracheal secretions, and his oxygen requirement increases. A chest x-ray shows a new consolidation in the left lower lobe. The hospital's local antibiogram shows high rates of methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa.
Which of the following antibiotic regimens is the most appropriate initial therapy?
- Ceftriaxone and azithromycin
- Ampicillin and gentamicin
- Vancomycin and piperacillin-tazobactam (correct answer)
- Clindamycin
Explanation: This patient meets the criteria for ventilator-associated pneumonia (VAP), which develops >48 hours after endotracheal intubation. Empiric therapy for VAP must cover multidrug-resistant organisms, including MRSA and Pseudomonas aeruginosa. The combination of vancomycin (for MRSA) and an anti-pseudomonal beta-lactam such as piperacillin-tazobactam provides appropriate broad-spectrum coverage pending culture results.
Question 8
A 32-year-old man with a history of IV drug use presents with a 4-week history of progressive dyspnea, dry cough, and fevers. His medical records show a CD4 count of 75 cells/mm³ six months ago, but he has not been taking antiretroviral therapy. His oxygen saturation is 89% on room air. A chest x-ray reveals diffuse bilateral ground-glass opacities.
Which of the following is the most appropriate next step to establish a definitive diagnosis?
- Sputum Gram stain and culture
- Tuberculin skin test
- Bronchoscopy with bronchoalveolar lavage (correct answer)
- Empiric treatment with ceftriaxone
Explanation: The clinical presentation of subacute dyspnea, hypoxia, and diffuse interstitial infiltrates in a severely immunocompromised patient (CD4 < 200) is highly suggestive of Pneumocystis jirovecii pneumonia (PJP). Because P. jirovecii cannot be cultured, a definitive diagnosis requires visualization of the cysts or trophozoites in a respiratory sample. Sputum induction can be attempted, but bronchoscopy with bronchoalveolar lavage (BAL) has a much higher diagnostic yield and is the most appropriate next step.
Question 9
A 58-year-old man with a history of chronic alcohol abuse and poor dental hygiene presents with a 4-week history of fever, night sweats, and a cough productive of copious amounts of foul-smelling sputum. A chest x-ray shows a 4-cm cavitary lesion with an air-fluid level in the posterior segment of the right upper lobe.
Which of the following is the most likely diagnosis?
- Tuberculosis
- Lung abscess (correct answer)
- Cavitating squamous cell carcinoma
- Pulmonary embolism with infarction
Explanation: This patient's presentation is classic for a lung abscess. Key features include the subacute onset of symptoms, risk factors for aspiration (alcoholism, poor dentition), production of purulent, foul-smelling (putrid) sputum indicative of anaerobic infection, and the characteristic chest x-ray finding of a cavitary lesion with an air-fluid level. The location in a gravity-dependent segment of the lung is also typical.
Question 10
A 58-year-old man was diagnosed with community-acquired pneumonia by his primary care physician 3 days ago and was started on oral amoxicillin-clavulanate. He calls the office today complaining of worsening shortness of breath, a persistent fever of 39.2°C (102.6°F), and a new feeling of confusion. His wife reports he seems lethargic.
What is the most appropriate recommendation for this patient?
- Switch antibiotic to oral levofloxacin
- Add a course of oral prednisone
- Continue current antibiotic for another 48 hours
- Go to the emergency department for immediate evaluation (correct answer)
Explanation: This patient is demonstrating clinical failure of outpatient pneumonia treatment. His worsening respiratory symptoms, persistent high fever, and new-onset confusion are signs of severe pneumonia that require hospitalization. He needs urgent evaluation in an emergency department for potential sepsis, respiratory failure, and the need for intravenous antibiotics and supportive care. Changing oral antibiotics would be inappropriate and unsafe.
Question 11
A 66-year-old man with a 40-pack-year smoking history is treated for right lower lobe pneumonia. His symptoms improve with a course of levofloxacin. However, a follow-up chest x-ray 6 weeks later shows persistence of the infiltrate. The patient also mentions an unintentional 15-lb weight loss over the past few months.
The persistence of the infiltrate on imaging is most concerning for which of the following underlying conditions?
- Infection with a drug-resistant organism
- Endobronchial obstruction (correct answer)
- Formation of a lung abscess
- Co-infection with an atypical pathogen
Explanation: A non-resolving or slowly resolving pneumonia, particularly in an older patient with a significant smoking history, should raise suspicion for an underlying endobronchial obstruction. The most common cause of such an obstruction is a bronchogenic carcinoma. The tumor can block a bronchus, leading to impaired drainage and post-obstructive pneumonia. The patient's history of weight loss further increases this suspicion. Further evaluation with a chest CT and/or bronchoscopy is warranted.
Question 12
An 80-year-old man undergoes an emergency colectomy for a perforated diverticulum. On postoperative day 3, while still intubated and mechanically ventilated, he develops a fever, leukocytosis, and increased oxygen requirements. His chest x-ray is unchanged. On postoperative day 5, a new infiltrate is noted in the right lower lobe.
This patient's pulmonary infection is best classified as which of the following?
- Community-acquired pneumonia
- Aspiration pneumonia
- Ventilator-associated pneumonia (correct answer)
- Postoperative atelectasis
Explanation: Ventilator-associated pneumonia (VAP) is defined as pneumonia that arises more than 48 hours after patients have been intubated and placed on mechanical ventilation. This patient developed a new infiltrate and signs of infection on postoperative day 5 while intubated, which perfectly fits the definition of VAP. While he may have aspirated (B), the correct classification in this context is VAP, which guides the choice of broad-spectrum antibiotics. Postoperative atelectasis (D) can cause fever but does not typically present as a new infiltrate with leukocytosis on day 5.
Question 13
A 68-year-old man was admitted to the hospital for a hip fracture repair. On hospital day 5, he develops a fever of 38.7°C (101.7°F), a new productive cough, and leukocytosis. A chest x-ray shows a new infiltrate in the right upper lobe. He has not required mechanical ventilation. His medical history is significant for a penicillin allergy that causes a rash.
Which of the following is the most appropriate empiric antibiotic regimen?
- Ceftriaxone
- Levofloxacin (correct answer)
- Azithromycin
- Ampicillin-sulbactam
Explanation: This patient has developed hospital-acquired pneumonia (HAP), defined as pneumonia occurring ≥48 hours after admission. Empiric therapy for HAP must cover for common nosocomial pathogens, including Pseudomonas aeruginosa. Levofloxacin is a respiratory fluoroquinolone with anti-pseudomonal activity and is an appropriate choice, especially given the patient's penicillin allergy. Ceftriaxone and azithromycin are used for CAP and lack reliable Pseudomonas coverage. Ampicillin-sulbactam also lacks reliable Pseudomonas coverage.
Question 14
A 50-year-old woman with no significant medical history presents to her primary care physician with a 3-day history of cough, fever, and right-sided pleuritic chest pain. A chest x-ray confirms a right middle lobe pneumonia. She is hemodynamically stable, well-hydrated, and her oxygen saturation is 98% on room air. She is considered a candidate for outpatient treatment.
Which of the following is the most appropriate approach to microbiologic diagnostic testing for this patient?
- Obtain sputum and blood cultures before starting antibiotics
- Perform urinary antigen testing for S. pneumoniae and Legionella
- No routine microbiologic testing is indicated (correct answer)
- Obtain serum procalcitonin level
Explanation: For healthy outpatients with community-acquired pneumonia who are not severely ill, routine microbiologic testing (such as pre-treatment sputum or blood cultures) is not recommended. The yield of these tests is low in the outpatient setting, and the results rarely alter empiric management, which is highly effective. Testing is generally reserved for patients with severe CAP, specific risk factors, or public health concerns.
Question 15
A 78-year-old resident of a nursing home with a history of dementia and dysphagia after a stroke develops a fever and cough. Physical examination reveals poor dentition and rhonchi in the right lower lung field. A chest x-ray shows an infiltrate in the superior segment of the right lower lobe. The patient is admitted to the hospital.
Which of the following antibiotic regimens provides the most appropriate empiric coverage for this patient?
- Azithromycin
- Vancomycin
- Ceftriaxone and metronidazole (correct answer)
- Doxycycline
Explanation: This patient's clinical presentation is highly suggestive of aspiration pneumonia. Risk factors include advanced age, nursing home residence, dementia, and dysphagia. Poor dentition increases the burden of anaerobic oral flora. The location of the infiltrate (superior segment of a lower lobe) is also classic for an aspiration event in a recumbent patient. Empiric treatment for aspiration pneumonia must include coverage for anaerobic bacteria. The combination of ceftriaxone (for gram-negatives and streptococci) and metronidazole (for anaerobes) is an excellent choice. Ampicillin-sulbactam or a carbapenem would also be appropriate.
Question 16
A 35-year-old nursing student undergoes routine screening for tuberculosis. She has no symptoms of active disease and her chest x-ray is normal. However, her tuberculin skin test (TST) shows 12 mm of induration. She has no known prior history of TB exposure or BCG vaccination.
Which of the following is the most appropriate management for this patient?
- No treatment is necessary
- Rifampin, isoniazid, pyrazinamide, and ethambutol for 2 months
- Isoniazid and pyridoxine for 9 months (correct answer)
- Repeat TST in 1 year
Explanation: This patient is a healthcare worker, and a TST result of ≥10 mm induration is considered positive. With a normal chest x-ray and no symptoms, she is diagnosed with latent tuberculosis infection (LTBI). Treatment is recommended to prevent progression to active disease. One of the standard, first-line regimens for LTBI is isoniazid daily for 9 months. Pyridoxine (vitamin B6) is co-administered to prevent isoniazid-induced peripheral neuropathy.
Question 17
A 68-year-old woman was admitted to the hospital with severe community-acquired pneumonia and started on ceftriaxone and levofloxacin. On day 3 of admission, her blood cultures from admission grow methicillin-sensitive Staphylococcus aureus (MSSA). She remains febrile and hypotensive.
Which of the following is the most appropriate change to her antibiotic regimen?
- Add intravenous vancomycin
- Continue the current regimen
- Discontinue ceftriaxone and levofloxacin and start nafcillin (correct answer)
- Add intravenous metronidazole
Explanation: The patient has MSSA bacteremia secondary to pneumonia. The treatment of choice for serious MSSA infections is an anti-staphylococcal penicillin (e.g., nafcillin, oxacillin) or a first-generation cephalosporin (e.g., cefazolin), as these are more effective than vancomycin or broad-spectrum agents. Once the pathogen is identified as MSSA, therapy should be de-escalated to the most effective, narrow-spectrum agent. Therefore, stopping the broad empiric coverage and starting nafcillin is the most appropriate step.
Question 18
A 28-year-old previously healthy woman presents to an urgent care clinic with a 4-day history of fever, chills, and a productive cough with rust-colored sputum. She denies any recent travel or sick contacts. On examination, her temperature is 38.6°C (101.5°F), blood pressure is 118/76 mm Hg, heart rate is 98/min, and respiratory rate is 22/min. Oxygen saturation is 97% on room air. Auscultation of the right lung reveals crackles and bronchial breath sounds. A chest x-ray shows a dense consolidation in the right lower lobe.
Which of the following is the most appropriate initial treatment for this patient?
- Amoxicillin
- Ceftriaxone and azithromycin
- Levofloxacin (correct answer)
- Vancomycin
Explanation: This patient has community-acquired pneumonia (CAP) and is stable for outpatient management. According to current guidelines, first-line treatment for outpatient CAP in healthy adults is either a respiratory fluoroquinolone (levofloxacin, moxifloxacin) or a macrolide (azithromycin) in areas with low pneumococcal resistance. High-dose amoxicillin is preferred only in areas with low macrolide resistance and when patient has no recent antibiotic use. Combination therapy with ceftriaxone and azithromycin is reserved for inpatient treatment.
Question 19
A 45-year-old man from Southeast Asia presents with a 2-month history of a persistent cough, a 10-lb weight loss, night sweats, and fatigue. A chest x-ray reveals a cavitary lesion in the apex of the right lung. A tuberculin skin test is positive with 18 mm of induration.
Which of the following is the most appropriate next step to confirm the diagnosis of active disease?
- Interferon-gamma release assay
- Sputum for acid-fast bacilli smear and culture (correct answer)
- Initiate empiric four-drug therapy
- Chest CT scan
Explanation: The patient's symptoms (chronic cough, weight loss, night sweats) and chest x-ray findings (apical cavitary lesion) are highly suspicious for active pulmonary tuberculosis (TB). While the TST is positive, it does not differentiate between latent and active infection. The definitive diagnosis of active pulmonary TB is made by identifying Mycobacterium tuberculosis in the sputum. Therefore, obtaining three consecutive morning sputum samples for acid-fast bacilli (AFB) smear, culture, and nucleic acid amplification testing (NAAT) is the crucial next step.
Question 20
A 40-year-old man with HIV and a CD4 count of 120 cells/mm³ presents with a 3-week history of non-productive cough, fever, and progressive dyspnea. Sputum samples for acid-fast bacilli smear are negative on three occasions. A chest x-ray shows diffuse reticulonodular infiltrates and mediastinal lymphadenopathy. Clinical suspicion for tuberculosis remains very high.
Given the negative sputum smears, which of the following is the most appropriate next step to diagnose this patient's condition?
- Interferon-gamma release assay
- Repeat chest x-ray in 2 weeks
- Bronchoscopy with bronchoalveolar lavage (correct answer)
- Start empiric treatment for community-acquired pneumonia
Explanation: In patients with HIV and low CD4 counts, pulmonary tuberculosis can present atypically (e.g., without classic apical cavities) and may be paucibacillary, leading to negative sputum AFB smears. When clinical suspicion is high despite negative smears, a more invasive procedure is needed to obtain a better respiratory sample. Bronchoscopy with bronchoalveolar lavage (BAL) allows for direct sampling of the lower airways and can provide material for AFB smear, culture, and nucleic acid amplification testing (NAAT), significantly increasing the diagnostic yield.