Quantitative sputum culture as a means of excluding false positive reports in the routine microbiology laboratory.

A relatively simple technique for sputum homogenization and dilution is described. Results show that this technique is reliable for isolation and quantitative culture of organisms from cases of chest infection. The technique has resulted in significant reduction in false positive reports, particularly when a system of interpretative reporting is utilized based on 10(7) organisms per millilitre of sputum being accepted as evidence of significant infection.