The 750mg dose of levofloxacin possesses enhanced activity against pathogens with higher MICs. A study by Lister using an in vitro pharmacokinetic model revealed that while the 500 mg dose of levofloxacin was as effective as 750 mg in killing ciprofloxacin-resistant S. pneumoniae strains with levofloxacin MICs of 1.4 or 1.8 μg/mL, the higher 750 mg levofloxacin dose was more effective in rapidly killing strains with levofloxacin MICs of 2.6 or 3.2 μg/mL (5). Therefore clinicians can have greater confidence that even pathogens with higher MICs will have a greater likelihood of being eradicated with the 750 mg dose. This will include S. pneumoniae strains with higher MICs, or organisms such as P. aeruginosa, a common cause of nosocomial pneumonia.In addition, the faster and more complete eradication of the pathogen results in an effective therapy with a shorter antimicrobial treatment; and it is less likely that resistance will emerge during or post therapy with the higher dose, an important benefit in this era of multi-drug resistant pathogens.