Basis for advising re-consultation if the person's condition deteriorates

• A significant deterioration may be caused by pneumonia that was not previously clinically apparent.

Basis for management options for people that do not improve, or who worsen, on antibiotics

• Based upon the known pathogens causing acute bronchitis, people that do not improve whilst receiving antibiotics are likely to have one of the following [Macfarlane et al, 2001]:
• An underlying viral infection.
• A streptococcal infection resistant to amoxicillin.
• An atypical bacterial infection not susceptible to any penicillin antibiotics.
• The majority of people who do not improve on antibiotics will have a viral infection and discontinuing the antibiotic will not cause any deterioration in their condition.
• In a minority of people, prescribing a second antibiotic may result in improvement when there is an underlying bacterial cause that was not susceptible to the first-line choice. This may be a reasonable option for people who are seriously ill with a pre-existing condition, when any further deterioration is likely to have serious consequences.
• Co-amoxiclav or doxycycline are suitable second-line antibiotics in people who have previously taken amoxicillin.
• Co-amoxiclav is a combination product containing amoxicillin and clavulanic acid. This is an inhibitor of beta-lactamase, an enzyme that is present in many penicillin-resistant bacteria, and helps amoxicillin retain its efficacy. In particular, co-amoxiclav should be effective against penicillin-resistant strains of Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae.
• Doxycycline has a different spectrum of activity to amoxicillin, and should be considered if previous amoxicillin failure was suspected to be due to Mycoplasma pneumoniae or Chlamydia pneumoniae (although this will not be known for certain in practice).
• If amoxicillin was not previously used due to allergy or other contraindications, it is reasonable to seek advice on second-line treatment from a microbiologist. A macrolide may be suitable, although this may not provide adequate coverage. Fluoroquinolones tend to be effective with few adverse effects, but prescribing these drugs in primary care should be restricted because of fears of growing resistance.

Basis for recommending pneumococcal vaccination

• S. pneumoniae is one of the pathogens known to cause acute bronchitis [Macfarlane et al, 2001].
• The effectiveness of pneumococcal vaccination in preventing morbidity and mortality from S. pneumoniae has been demonstrated in a meta-analysis of 14 randomized controlled trials (n = 48,837) [Cornu et al, 2001].

Basis for recommending influenza vaccine

• The influenza virus is one of the pathogens known to cause acute bronchitis [Macfarlane et al, 2001].
• A number of randomized controlled trials and cohort studies have demonstrated that influenza immunization is effective for:
• Reducing the incidence of influenza.
• Reducing morbidity and mortality from secondary bacterial infections following influenza, particularly in at-risk groups.