[theartofbone]

I choose E, since they are good/perhaps the best choice anti psuedomonals on the list.

 

[theartofbone]

i strongly wanted to choose D (just because of piperacilin), but tmsid's explanation is pushing me towards E now, because the 2 combinations combats pseudomonas synergistically.

For all USMLE style questions, when Pseudomona is the potential culprit, always choose the option w/ two effective anti-pseudomonals. Yes, Piperacillin works most the time, but so does an aminoglycoside + a 4th gen cephalosporin (Cefepime). It's like in war; 2 tanks are better than 1, 2 battle cruisers > 1 and lastly, $100 is better than $50 dollars.