What are the best antibiotic (abx) eye drops?

Best Antibiotic Eye Drops for Ocular Infections

Fourth-generation fluoroquinolones, particularly moxifloxacin 0.5%, are the best antibiotic eye drops for most bacterial eye infections due to their broad-spectrum coverage, excellent tissue penetration, and proven efficacy. 1

First-Line Treatment Options

For Mild to Moderate Bacterial Conjunctivitis:

• Moxifloxacin 0.5%: Instill one drop in the affected eye 3 times daily for 7 days 2

  • Provides superior efficacy with complete resolution in 81% of cases within 48 hours 3
  • Self-preserved formulation at near-neutral pH (6.8) minimizes ocular irritation 4
  • Available in a xanthan gum-based formulation (Moxeza) that allows twice-daily dosing 5

• Gatifloxacin 0.3%: Alternative fourth-generation fluoroquinolone with similar efficacy 1

• Other options:

  • Besifloxacin 0.6%: Particularly effective against ciprofloxacin and methicillin-resistant staphylococci 1
  • Levofloxacin 1.5%: FDA-approved for bacterial keratitis with efficacy equal to ofloxacin 0.3% 6
  • Ciprofloxacin 0.3%, Ofloxacin 0.3%: Earlier generation options but with increasing resistance concerns 6, 1

Treatment for Severe Infections

For Severe or Central Keratitis:

• Combination therapy with fortified antibiotics:

  • Fortified cefazolin 50 mg/ml or ceftazidime 50 mg/ml PLUS
  • Fortified tobramycin 14 mg/ml or gentamicin 14 mg/ml 1
  • Initial loading dose: Every 5-15 minutes, then hourly until improvement 6

• For MRSA infections: Consider vancomycin 15-50 mg/ml (fortified) 1

• For vancomycin-resistant cases: Consider topical linezolid 1

• For multidrug-resistant P. aeruginosa: Consider topical colistin 0.19% 1

Antibiotic Resistance Considerations

• Increasing resistance to fluoroquinolones has been observed, particularly in MRSA (42% of staphylococcal isolates) 6, 1

• Risk factors for resistance include:

  • Recent fluoroquinolone use
  • Hospitalization
  • Advanced age
  • Recent ocular surgery 1

• Fourth-generation fluoroquinolones (moxifloxacin, gatifloxacin) have better gram-positive coverage than earlier generations 6, 7

• Moxifloxacin has better mutant prevention characteristics than other fluoroquinolones, potentially reducing resistance development 7

Treatment Duration and Monitoring

• Continue treatment until clinical resolution 1
• For severe infections, monitor daily until improvement is confirmed 1
• Average treatment duration for severe infections may be longer (e.g., 41.9 days for Moraxella keratitis) 1

Clinical Pearls and Pitfalls

• Pearl: Single-drug fluoroquinolone therapy is as effective as combination therapy for most bacterial eye infections 6, 1
• Pitfall: Underestimating the importance of frequent application in severe infections; hourly dosing may be necessary initially
• Pearl: Moxifloxacin penetrates ocular tissues better than gatifloxacin and older fluoroquinolones 7
• Pitfall: Failing to consider local resistance patterns when selecting an antibiotic
• Pearl: Cycloplegic agents may be used to decrease pain and prevent synechiae formation when substantial anterior chamber inflammation is present 6

In summary, moxifloxacin 0.5% represents the best choice for most bacterial eye infections due to its broad spectrum of activity, excellent tissue penetration, and convenient dosing schedule. For severe infections, combination therapy with fortified antibiotics may be necessary.