Introduction

A complex inter-relationship exists between respiratory tract infection and bronchitis, asthma, emphysema and bronchiectasis. This chapter will address the role of infection within the context of the current knowledge of the overall respiratory pathology of these conditions.

Acute bronchitis

The authors agree with Pennington's view that ‘acute bronchitis in the normal host simply represents a less extensive version of community-acquired pneumonia. In the absence of chronic bronchopulmonary disease the aetiological agents are virtually identical.’ Cough is the only consistent symptom but is typically associated with sputum production at some stage of the illness. The discomfort of tracheitis and a preceding cold or influenza-like illness are common. Unless there is co-existent bronchopulmonary disease there are usually no physical signs or auscultatory changes and physiologically there may be no change in pulmonary function although airway reactivity may increase.

Depending on the age of the patient, severity of the illness and the possibility of co-morbidity, a chest X-ray and sputum and serological testing may be indicated, but usually symptomatic treatment and observation or empirical antibiotic therapy is started without other investigation. Antibiotic selection should be based on the same rationale as for community-acquired pneumonia. See also Chapter 17.

Differentiating between viral, mycoplasma, bacterial, allergic and toxic gas aetiologies may be very difficult. An occupational history may be important and with recurrent episodes of so-called ‘bronchitis’ one must bear in mind the possibility of asthma or a non-infectious aetiology.