A 62-year-old man with a history of chronic obstructive pulmonary disease presents with cough, headache, dyspnea, and watery diarrhea that started 6 days ago. He was seen at a local urgent care 4 days ago and prescribed amoxicillin-clavulanate without improvement. He is ill appearing with a fever of 38.7°C and inspiratory rales on auscultation. Which of the following results would be most consistent with his diagnosis?

Right upper lobe infiltrate with bulging fissure on chest X-ray
Serum potassium 6 mEq/L
Serum sodium 128 mEq/L
Sputum gram stain with gram positive cocci in pairs

The right answer is Serum sodium 128 mEq/L

Explanation:

The patient is diagnosed with Legionella pneumonia. It is a atypical type of pneumonia and is caused by a bacteria called as Legionella. Common sign and symptoms are:

The correct answer is Serum sodium 128 mEq/L and other options are not because:

Right upper lobe infiltrate with bulging fissure on chest X-ray is seen in the case of Klebsiella pneumoniae and in the case of Legionella usually numerous polymorphonuclear lymphocytes are observed.

Sputum gram stain with gram positive cocci in pairs occurs in the case of pneumococcal pneumonia.

Diarrhea causes excessive potassium loss not increase in potassium. Also patients with Legionella have decreased sodium levels.

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all the above is what i would say