What is the comparative bacteria coverage of cefuroxime, amoxicillin (Amoxil), and levofloxacin (Levaquin)?

Comparative Bacterial Coverage: Cefuroxime vs. Amoxicillin vs. Levofloxacin

Levofloxacin provides the broadest and most reliable coverage against respiratory pathogens, including both typical and atypical organisms, with superior activity against Streptococcus pneumoniae (including resistant strains), Haemophilus influenzae, and Moraxella catarrhalis compared to cefuroxime and amoxicillin. 1, 2

Gram-Positive Coverage

Streptococcus pneumoniae

• Levofloxacin demonstrates excellent activity with MICs of 0.25-2 mg/L and maintains efficacy against penicillin-resistant strains (MDRSP), with clinical success rates of 95% 3, 4
• Amoxicillin (especially high-dose formulations) provides good coverage with 95-97% activity based on PK/PD breakpoints, though activity decreases against penicillin-resistant strains 1
• Cefuroxime shows moderate activity (63-75% based on PK/PD breakpoints), with inherently lower potency than amoxicillin—baseline MICs are fourfold higher 1, 5

Staphylococcus aureus

• Levofloxacin covers methicillin-sensitive S. aureus (MSSA) but requires vancomycin addition for MRSA 3
• Cefuroxime provides coverage for MSSA only 5
• Amoxicillin has no reliable activity against S. aureus due to beta-lactamase production 1

Gram-Negative Coverage

Haemophilus influenzae

• Levofloxacin achieves 95-100% coverage with excellent activity 1, 2, 4
• Amoxicillin (standard formulation) shows 70-85% activity; amoxicillin-clavulanate increases this to 95-100% 1
• Cefuroxime demonstrates 70-85% activity, less than levofloxacin but comparable to standard amoxicillin 1, 5

Moraxella catarrhalis

• Levofloxacin provides 100% coverage 1, 4
• Amoxicillin-clavulanate achieves 100% coverage (clavulanate overcomes beta-lactamase) 1
• Cefuroxime shows only 50% activity 1

Enterobacteriaceae (E. coli, Klebsiella, Enterobacter)

• Levofloxacin demonstrates broad activity against most Enterobacteriaceae 5, 2
• Cefuroxime provides good coverage for E. coli and Klebsiella species 5
• Amoxicillin has limited activity; amoxicillin-clavulanate improves coverage 1

Pseudomonas aeruginosa

• None of these agents provide reliable monotherapy coverage 1
• Levofloxacin 750 mg can be used but must be combined with an antipseudomonal beta-lactam (ceftazidime or piperacillin-tazobactam) 1, 3
• Cefuroxime and amoxicillin have no clinically significant activity 5

Atypical Pathogen Coverage

Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila

• Levofloxacin achieves clinical success rates of 96%, 96%, and 70% respectively for these atypical pathogens 3, 2
• Cefuroxime has no activity against atypical pathogens 1, 5
• Amoxicillin has no activity against atypical pathogens 1

Clinical Implications by Infection Type

Community-Acquired Pneumonia

• Levofloxacin 750 mg daily for 5 days achieved 90.9% clinical success as monotherapy, superior to ceftriaxone/cefuroxime combination (83%) 3
• Combination therapy (beta-lactam + macrolide) is recommended when using cefuroxime or amoxicillin to cover atypical pathogens 1
• Levofloxacin provides the advantage of monotherapy coverage for both typical and atypical organisms 1

Acute Exacerbations of Chronic Bronchitis

• Levofloxacin achieved 78-94.6% clinical success and 77-97% bacteriological eradication 6, 4
• Cefuroxime showed comparable efficacy (75-83.3% clinical cure) but requires longer treatment duration 4, 7
• Amoxicillin-clavulanate demonstrated similar efficacy to cefuroxime 7

Critical Resistance Considerations

Fluoroquinolone Resistance

• S. pneumoniae resistance to levofloxacin remains <1% in the U.S., and resistance does not emerge rapidly during therapy 8, 4
• However, ciprofloxacin lacks adequate pneumococcal coverage and is contraindicated for CAP 1
• P. aeruginosa can develop resistance during levofloxacin monotherapy 4

Beta-Lactam Resistance

• Low-level penicillin resistance in S. pneumoniae does not affect clinical outcomes with high-dose amoxicillin 1
• Cefuroxime activity is significantly compromised against penicillin-resistant pneumococci 1

Pharmacokinetic/Pharmacodynamic Advantages

• Levofloxacin exhibits concentration-dependent killing with prolonged post-antibiotic effect, allowing once-daily dosing 1, 2, 8
• Cefuroxime and amoxicillin demonstrate time-dependent killing requiring multiple daily doses to maintain adequate serum concentrations above MIC for 40-50% of the dosing interval 1
• Levofloxacin achieves high tissue concentrations in lung, sputum, and pleural fluid, exceeding plasma levels 5, 2, 6

Common Pitfalls to Avoid

• Do not use cefuroxime or amoxicillin monotherapy when atypical pathogens are suspected—combination with a macrolide is essential 1
• Do not use levofloxacin monotherapy for Pseudomonas infections—always combine with an antipseudomonal beta-lactam 1, 3
• Avoid fluoroquinolones in patients with recent fluoroquinolone exposure within 90 days due to resistance risk 9
• Do not assume ciprofloxacin and levofloxacin are interchangeable—ciprofloxacin lacks adequate pneumococcal coverage 1