Non-pneumonic LRTI is defined here as lower respiratory tract symptoms in a previously well patient with no chest signs and is associated with infection by all of the major respiratory viral groups. A proportion of cases are caused by Mycoplasma pneumoniae, Bordetella pertussis and Chlamydia pneumoniae (for further information, see Annex 2 to this guideline, available on the SIGN website). At the present time, the exact role of atypical pathogens in this disease is not clear. Haemophilus influenzae and Streptococcus pneumoniae may be associated with secondary infection though their presence in nasopharyngeal commensal flora makes this difficult to determine.⁵⁰

6.1 Investigation

The evidence suggests that chest x-ray and blood tests for C-reactive protein are not helpful in the community management of non-pneumonic LRTI. Sputum purulence or a positive sputum culture are generally not helpful (see section 5 for details of the evidence base). Evidence level 2+

Sputum culture, chest x-ray and blood tests for CRP should not be carried out routinely in non-pneumonic LRTI.

6.2 Treatment

Several randomised controlled trials and a number of meta-analyses and systematic reviews have investigated the treatment of non-pneumonic LRTI in the community^76,77,78,79 and have shown that antibiotic treatment of non-pneumonic LRTI leads to no or minimal advantage.^78,80 Evidence level 1++

Specific antibiotic therapy against mycoplasma or chlamydia is not helpful.⁸¹ Any advantages are outweighed by the disadvantages of drug side effects and potential resistance development. Evidence level 4

Antibiotics should not normally be prescribed for previously well patients who do not have signs in the chest or features of severity (see Box 1).

Sputum purulence alone is not an indication for antibiotics in a previously well patient with no chest signs.

GPs should give non-pneumonic LRTI patients written information to help explain the illness, to explain the decision not to prescribe an antibiotic and to reduce reconsultation rates (see section 10).

There is a significant reconsultation rate in non-pneumonic LRTI patients. Guidance on reducing this reconsultation rate is provided in sections 7-9.