Aspiration pneumonia--oropharynx or enteric Klebsiella?

[ChessMaster3000]

The fact that aspiration pna results from aspiration of oropharyngeal contents is well tested. However, we also know that klebsiella can cause aspiration pna in alcoholics, and this is an enteric organism.

Thus, when presented with an alcohol with an aspiration pneumonia (RLL most likely), besides foul-smelling breath to indicate anaerobic oropharyngeal contents, and in the absence of currant jelly sputum (which I can't see NBME going for these days), how would one distinguish btw oropharyngeal aspiration and Klebsiella enteric aspiration?

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[Snuke]

This is a good question, and it has tripped me up. They are difficult to tell apart.

For the most part, it's going to be oropharyngeal organisms. Enteric bugs (including Bacteriodes), will often create an abscess, so you'll see air-fluid levels on CT (though I'm not sure if Klebsiella would?). That's the only time I've seen it presented where there was no obvious clue. Usually they'll give you some help with a gram stain or some other clue.

I'd be interested in what other people think, too.