This recommendation is consistent with those of the Health Protection Agency [HPA and Association of Medical Microbiologists, 2008], with the exception that CKS also recommends the use of macrolides in the event that amoxicillin or doxycyline is unsuitable for the person to be treated.

• Empirical treatment is necessary as sputum samples are impractical for identifying a causative pathogen in primary care [SIGN, 2002; British Thoracic Society, 2004].
• There is no evidence from controlled trials to support the use of one antibiotic over another in the treatment of acute bronchitis. Therefore the choice of antibiotic should reflect their in vitro efficacy against the pathogens most likely to be involved, especially Streptococcus pneumoniae and Haemophilus influenzae.
• Amoxicillin provides coverage against most of the bacteria involved in acute bronchitis, including penicillin-intermediate resistant S. pneumoniae (bacteria in an intermediate stage of developing full penicillin resistance), when used at adequate doses [Bush, 2003; British Thoracic Society, 2004]. It has a favourable risk/benefit ratio, with few adverse effects.
• Doxycycline is active against most of the bacteria that cause bronchitis, including H. influenzae and, less commonly encountered, Mycoplasma pneumoniae [Chopra, 2003]. Oxytetracycline is another option, but requires more frequent dosing.
• Clarithromycin is a suitable alternative to amoxicillin in people allergic to penicillin. It is active against most of the bacterial pathogens involved in acute bronchitis [Bryskier and Butzler, 2003], although resistance to them is increasing, especially in H. influenzae.
• Clarithromycin is recommended in preference to erythromycin by the BTS guidelines for the management of community acquired pneumonia, on the basis of improved gastrointestinal tolerance and an easier dosing schedule [British Thoracic Society, 2009].