Question #2 explained:
Which of the following has activity against Gram negative rod Pseudomonas aeruginosa?
A. Ceftriaxone – INCORRECT: will cover many Gram negatives but unlike ceftazidime this third-generation cephalosporin lacks Pseudomonas coverage
B. Moxifloxacin – INCORRECT: unlike ciprofloxacin and levofloxacin, this fluoroquinolone lacks Pseudomonas coverage
C. Tigecycline – INCORRECT: while tigecycline covers many organisms (e.g., VRE, MRSA, ESBLs, CRE), Pseudomonas is the major hole in its spectrum of activity
D. Aztreonam – CORRECT: this monobactam is frequently over-looked, but with only Gram negative activity, it can be an option for Pseudomonas
E. Vancomycin – INCORRECT: vancomycin only has Gram positive activity (just like daptomycin and telavancin) and Pseudomonas is a Gram negative bacteria