Levofloxacin is a fluoroquinolone antibiotic, marketed by Ortho-McNeil under the trade name Levaquin. Chemically, levofloxacin is the S-enantiomer (L-isomer) of ofloxacin.

Levofloxacin is effective against a number of gram-positive and gram-negative bacteria. Because of its broad spectrum of action, levofloxacin is frequently prescribed empirically for a wide range of infections (e.g. pneumonia, urinary tract infection) before the specific causal organism is known. If the causal organism is identified, levofloxacin may be discontinued and the patient may be switched to an antibiotic with a narrower spectrum of activity.

Gram-positive bacteria