An elderly male develops fever 3 days after cholecystectomy. He becomes sho of breath, andCXR shows a new right lower lobe infiltrate. Sputum Gram stain shows gram-positive cocci in clumps, and preliminary culture results suggest staphylococci. Initial antibiotic of choice is
**Core Concept**
The question is testing the ability to identify the initial antibiotic of choice for a postoperative patient with suspected staphylococcal pneumonia, specifically in the context of a recent cholecystectomy.
**Why the Correct Answer is Right**
In this scenario, the patient is at risk for postoperative pneumonia due to the recent surgical stress and the presence of a new lung infiltrate on CXR. Staphylococci are a common cause of postoperative infections, and in this case, the Gram stain supports the presence of gram-positive cocci in clumps. The initial antibiotic of choice should cover methicillin-susceptible Staphylococcus aureus (MSSA), which is the most common cause of staphylococcal pneumonia. The correct antibiotic is a beta-lactamase-resistant penicillin, such as nafcillin, which is effective against MSSA.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because vancomycin is typically reserved for patients with suspected methicillin-resistant Staphylococcus aureus (MRSA) infections or in cases where the patient has a history of MRSA colonization or infection.
* **Option B:** This option is incorrect because ceftriaxone is a cephalosporin antibiotic that is not reliably effective against MSSA due to the presence of beta-lactamase production.
* **Option C:** This option is incorrect because ciprofloxacin is a fluoroquinolone antibiotic that is not typically used as the initial treatment for staphylococcal pneumonia due to concerns regarding resistance.
**Clinical Pearl / High-Yield Fact**
In postoperative patients with suspected staphylococcal pneumonia, it is essential to consider the possibility of methicillin-resistant Staphylococcus aureus (MRSA) and to use vancomycin as part of the initial empiric antibiotic regimen, especially in patients with a history of MRSA colonization or infection.
**Correct Answer:** D. Nafcillin