Improving the use of sputum cultures in lower respiratory tract infection

The clinical value of sputum culture in suspected lower respiratory tract infection (LRTI) remains contentious. The quality of samples submitted significantly impacts their clinical usefulness.

Using pre-defined criteria we prospectively analysed the appropriateness of sputum samples submitted from consecutive patients with suspected LRTI attending two acute hospital units over ten weeks. We then provided an education package for staff on when and how to collect appropriate sputum samples, and repeated the evaluation.

Our intervention reduced sample numbers from 347 to 133, simultaneously increasing the proportion of appropriately sent samples from 40.5 to 60.2% (p=0.001) and reducing cost. Appropriate sampling was associated with a higher yield of pathogens (relative risk 1.51, 95% confidence intervals 1.03-2.21, p=0.03). The rate at which sputum samples appeared to alter clinicians' management remained low and constant at 18% pre- and post-intervention.

A simple educational intervention can significantly increase appropriateness of sputum sampling, reducing workload and cost.