Levofloxacin is relatively new fluoroquinolone antibiotic, marketed by Ortho-McNeil under the brand 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 in hospitals for pulmonary infections before the specific causal organism is known. Once the causal organism is known, levofloxacin is discontinued and the patient is given a narrow-spectrum antibiotic.

Gram-positive bacteria

• Enterococcus faecalis (many strains are only moderately susceptible)
• Staphylococcus aureus (methicillin-susceptible strains)
• Staphylococcus epidermidis (methicillin-susceptible strains)
• Staphylococcus saprophyticus
• Streptococcus pneumoniae (including penicillin-resistant strains*)
• Streptococcus pyogenes

Gram-negative bacteria

• Enterobacter cloacae
• Klebsiella pneumoniae
• Pseudomonas aeruginosa
• Escherichia coli
• Legionella pneumophila
• Serratia marcescens
• Haemophilus influenzae
• Moraxella catarrhalis
• Haemophilus parainfluenzae
• Proteus mirabilis
• Campylobacter

Other

• Chlamydia pneumoniae
• Mycoplasma pneumoniae

Some information extracted from Levaquin Prescribing information.