BACKGROUND Postbronchoscopy fever can develop in 5-16% of adult patients. The microbiological contribution to postbronchoscopy fever is unclear.

OBJECTIVE To elucidate the effect of prophylactic antibiotics on the development of postbronchoscopy fever and pneumonia.

DESIGN Study patients were randomised to receive no treatment or oral amoxicillin/clavulanate 30 min before flexible bronchoscopy. The primary outcome variable was the frequency of postbronchoscopy fever and pneumonia. White blood cell counts, C-reactive protein and the serum pyrogenic cytokines interleukin (IL) 1β, IL-6 and tumour necrosis factor-alpha were measured before and after bronchoscopy.

RESULTS Of 143 subjects enrolled in the study, the final analysis was performed among 67 subjects in the prophylaxis group and 64 in the control group. The frequency of postbronchoscopy fever did not differ between the groups (25.4% for the prophylaxis group vs. 26.6% for controls, P > 0.05). Pneumonia developed in 1.5% of the prophylaxis group and 4.7% of the controls. There was no bacteraemia in either group. Serum pyrogenic cytokines did not differ between the groups.

CONCLUSIONS Prophylactic antibiotics before bronchoscopy did not reduce the frequency of postbronchoscopy fever and did not affect serum levels of pyrogenic cytokines. These findings suggest that microbiological factors may not be responsible for the development of postbronchoscopy fever.