A 57-year-old man who just returned from a cruise to the Bahamas comes to the emergency department with fever, nonproductive cough, and shortness of breath for the past 2 days. He has also had a headache, abdominal pain, and diarrhea for a day. The patient has a history of type 2 diabetes mellitus and has smoked a pack of cigarettes daily for 20 years. He does not use alcohol or illicit drugs. His temperature is 39.2 C (102.6 F), blood pressure is 110/65 mm Hg, pulse is 80/min, and respirations are 18/min. The patient's pulse oximetry shows 97% on room air. Lung examination shows crackles bilaterally. The abdomen is soft and nontender. The patient seems confused at times during the examination. His serum glucose is normal; serum sodium is 128 mEq/L. Chest x-ray demonstrates bilateral interstitial infiltrates. He is admitted to the ward. Which of the following antibiotics should be given to this patient?

Question

A 57-year-old man who just returned from a cruise to the Bahamas comes to the emergency department with fever, nonproductive cough, and shortness of breath for the past 2 days.  He has also had a headache, abdominal pain, and diarrhea for a day.  The patient has a history of type 2 diabetes mellitus and has smoked a pack of cigarettes daily for 20 years.  He does not use alcohol or illicit drugs.  His temperature is 39.2 C (102.6 F), blood pressure is 110/65 mm Hg, pulse is 80/min, and respirations are 18/min.  The patient's pulse oximetry shows 97% on room air.  Lung examination shows crackles bilaterally.  The abdomen is soft and nontender.  The patient seems confused at times during the examination.  His serum glucose is normal; serum sodium is 128 mEq/L.  Chest x-ray demonstrates bilateral interstitial infiltrates.  He is admitted to the ward.  Which of the following antibiotics should be given to this patient?

Quizplus · Accepted Answer

11ec25c8_d45b_b782_bc81_5516a8145300_MD0003_00 This patient has bilateral lung infiltrates, confusion, and diarrhea following travel. Legionella pneumonia (Legionnaires' disease) must be considered. Travel-associated Legionnaires' disease due to contaminated water supplies is a well-documented condition linked to cruise ships and hotels. Symptoms that help distinguish an atypical pneumonia due to Legionella from other causes of community-acquired pneumonia (CAP) include high-grade fever (>38.8 C [101.8 F]), gastrointestinal symptoms, and neurologic symptoms (eg, confusion, ataxia). Lung examination typically shows rales, and chest radiograph most often reveals patchy unilobar or interstitial infiltrates. Hyponatremia and hepatic dysfunction are common. Legionella pneumophila is a gram-negative rod that stains poorly because it is primarily intracellular; therefore, sputum Gram stain showing many neutrophils but no organisms is also characteristic. The definitive diagnosis may be made by culture in combination with urinary antigen testing. Legionnaires' disease is treated with antibiotics that achieve high intracellular concentration, particularly newer macrolides (eg, azithromycin) or fluoroquinolones (eg, levofloxacin). The latter are favored when the illness is severe enough to warrant admission. (Choice A) Amoxicillin/clavulanate is typically used in sinusitis, otitis media, and some cases of CAP but not in Legionnaires' disease. It has activity against beta-lactamase-producing Haemophilus and Moraxella species. (Choice B) Ceftriaxone has good activity against pneumococcus as well as Haemophilus and Moraxella. It does not have activity against L pneumophila or other causes of atypical pneumonia. (Choice C) Clindamycin, a lincosamide (related to macrolides), is not used against L pneumophila. It is used primarily to treat infections with anaerobic organisms and in some patients with lung abscess or aspiration pneumonia (eg, penicillin allergy). It is associated with Clostridioides difficile colitis. (Choice E) Vancomycin is used to treat patients with nosocomial pneumonia, when the probability of methicillin-resistant Staphylococcus aureus is higher. Vancomycin has no activity against Legionella or most other causes of atypical pneumonia. Educational objective: Legionella pneumophila is an intracellular, gram-negative organism commonly spread by aerosols or droplets from contaminated water supplies. A history of recent travel is common. Extrapulmonary symptoms such as confusion, ataxia, or diarrhea are suggestive of Legionnaires' disease. Treatment options include macrolides or fluoroquinolones. References: Infectious Disease Society of America/American Thoracic Society consensus guidelines on the management of community-acquired pneumonia in adults (http://www.ncbi.nlm.nih.gov/pubmed/17278083) Legionella infections and travel associated legionellosis (http://www.ncbi.nlm.nih.gov/pubmed/21995862) Clinical outcomes for hospitalized patients with Legionella pneumonia in the antigenuria era: the influence of levofloxacin therapy (http://www.ncbi.nlm.nih.gov/pubmed/15736010)

A 57-Year-Old Man Who Just Returned from a Cruise to the Bahamas