7.1 Exacerbations of COPD

Antibiotics are only likely to be of benefit in purulent exacerbations of COPD if increased purulent sputum and dyspnoea are present. In pneumonia, urgent treatment is indicated, with appropriate adjustment on receipt of (laboratory) investigation results. If sputum is available for culture it should be obtained prior to commencing antibiotic. If antibiotic susceptibilities are available then an appropriate agent can be chosen from the laboratory report based on toxicity, mode of administration, allergy, likelihood of resistance developing, cost, dosing schedule, compliance, co-morbidity and severity of disease. Several groups of antibiotic are appropriate for use in purulent exacerbations of COPD. Traditionally, in the UK, penicillin and macrolides have been used although they are less successful against Haemophilus influenzae. Tetracyclines are an alternative.

7.2 Non-pneumonic LRTI

In non-pneumonic LRTI, the probability of obtaining benefit from antibiotics may be similar to the probability of being harmed by them.⁸² A cough and discoloured sputum do not require antibiotics in the absence of focal signs in the chest. Cough persisting for two to three weeks after presentation, is unlikely to resolve or improve more quickly as a result of antibiotic therapy.⁸³ Audits have shown poor quality antibiotic prescribing both in hospitals and the community.^84,85,86,87 The National Audit Commission has criticised GPs for their unnecessary use of antibiotics. Approximately 60% of GPs' antibiotic use is for respiratory tract symptoms, so it is to be hoped that this guideline will contribute to improved prescribing quality, in particular reduction in antibiotic use where benefits of antibiotics will not or are unlikely to be obtained. As well as making judgements about individual prescriptions, clinicians also need to consider the societal aspect of antibiotic prescription given the current pandemic of resistance in the community.^88,89,90

7.3 Important issues to consider

Recent evidence correlates increasing macrolide resistance with high use of macrolides, with increased resistance arising within a very short time period. There is some evidence that long half-life macrolides are more likely to cause resistance problems although only high-level resistance may be of clinical significance.⁹¹

Optimal dosing of antibiotic (see Annex 1 to this guideline on the SIGN website) is encouraged to hasten bacteriological (and clinical) cure, reduce relapses and shorten length of treatment. Inappropriate treatment, e.g. long term or low dose is associated with selection of resistance leading to treatment failure.⁹²

If susceptibility tests suggest resistance or disease severity indicates it, then a quinolone can be an appropriate choice. Quinolones should be used with caution because of potential toxicity and the development of resistance.^93,94

In the absence of detailed susceptibility data, data from a 2000 National Survey (see Annex 3 on the website) of resistance in respiratory tract pathogens or data from a local laboratory may be useful. Scottish data from Alert organism surveillance suggests reduced penicillin susceptibility in pneumococci is relatively rare and macrolides resistance is <10%. Although Scotland appears to have relatively low levels of resistance, this should be an added stimulus to reducing inappropriate use and preventing the development of resistant organisms.⁹⁵

No evidence exists to guide on the optimum length of prescribing. Persistant sputum purulence suggests either a resistant organism or non-bacterial aetiology and other investigations may be appropriate.⁴⁵

Recent treatment or travel abroad is associated with carriage and or infection with antibiotic resistant organisms. High antibiotic consumption in a practice is associated with high resistance rates both in individual patients and in the practice as a whole, often resulting in reduced antibiotic susceptibility in Streptococcus pneumoniae or beta-lactamase producing Haemophilus influenzae .^{10,96,97,98,99}

Reconsultation is due as often to side effects of antibiotics as it is to treatment failure.¹¹