Uses of Quantitative Analyses of Bacterial Populations in Sputum

In most patients with acute bacterial infections of the respiratory tract, routine cultures provide data which enable the physician to administer appropriate antibacterial agents. Occasionally, these cultures give insufficient evidence to assure the physician that his therapeutic regimen is best for the patient. In such cases, quantitative bacteriologic analyses of sputum specimens may be helpful. Seven cases are presented in which quantitative studies provided important information. The uses of the technique fell into three categories: evaluation of dual infections, analysis of the efficacy of therapy in severe infections, and separation of the harmless carrier state from potentially dangerous bacteriologic infection or superinfection.