#76 Amoxicillin, Still an A-List Antibiotic for Infections of the Airway

CLINICAL QUESTION

QUESTION CLINIQUE

When needed, are beta-lactam antibiotics (such as amoxicillin) a reasonable choice in mild-to-moderate bacterial respiratory tract infections in primary care?

BOTTOM LINE

RÉSULTAT FINAL

In mild-to-moderate respiratory tract infections that require antibiotics, there is little evidence of benefit of broader-spectrum antibiotics over traditional beta-lactam antibiotics like amoxicillin in primary care. The only exception may be slight benefits for broader-spectrum in COPD patients, but these results are inconsistent.

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EVIDENCE

DONNÉES PROBANTES

Overall lower-respiratory tract infections:

Cochrane review¹of 16 randomized controlled trials (RCTs) of 2,648 patients with any kind of lower-respiratory tract infection:
No statistically significant difference between azithromycin and amoxicillin with/without clavulanate.

Community-acquired pneumonia (CAP):

Cochrane review:² Only one randomized controlled trial (RCT) comparing a beta-lactam antibiotic to another antibiotic in outpatients with CAP
- Authors could not extract outcome data for this comparison.
In CAP patients, including those hospitalized:
- Cochrane review³ of 28 RCTs (5,939 patients) and 2 subsequent RCTs:^4,5
  - No benefit in mortality or clinical efficacy with broader coverage for atypicals compared to beta-lactam monotherapy.

COPD:

RCT with 137 mild-to-moderately symptomatic primary care patients with acute exacerbation of COPD.⁶
- No difference in clinical cure between amoxicillin versus amoxicillin/clavulanate (91% versus 93%).
Systematic review⁷of 12 RCTs including 2,261 patients with chronic bronchitis (not necessarily COPD) compared “1st-line” antibiotics (like amoxicillin or doxycycline) versus “2nd-line” antibiotics (like macrolides and quinolones) for acute exacerbations:
- Symptom resolution/improvement: 85% for 1st-line antibiotics versus 91% for 2nd-line (difference statistically significant).
  - Studies ranged from 19% worse to 8% better with first-line antibiotics, no heterogeneity testing was reported
  - No difference in mortality.

Sinusitis:

Systematic review⁸ of 8 RCTs including 2,133 patients found no difference in clinical cure between beta-lactams and fluoroquinolones.
Two RCTs (total 359 children) compared amoxicillin to amoxicillin-clavulanate for acute sinusitis and neither found benefit with amoxicillin-clavulanate.^9,10

Context:

Majority of respiratory tract infections are viral and will not require antibiotics.
Macrolide resistance in Streptococcus pneumoniae is rapidly increasing (2% in 1993 to 24% in 2009), whereas resistance to amoxicillin is just over 3%.¹¹
Limited data report increasing prevalence of Haemophilus influenza among upper respiratory tract infections after the introduction of the conjugated pneumococcal vaccine, although clinical impact has not been demonstrated in well-designed RCTs.¹²