Many microorganisms commonly isolated in human diagnostic microbiology laboratories exhibit specific morphologic or biochemical traits that can be determined rapidly upon obtaining a pure colony. When such rapidly obtained parameters allow reliable identification of the organism with a high degree of certainty, the necessity of performing more time-consuming tests is decreased, and timely patient care is enhanced.

Clinical and Laboratory Standards Institute document M35-A2--Abbreviated Identification of Bacteria and Yeast; Approved Guideline--Second Edition includes the minimum identification criteria that can be used to rapidly identify a limited number of organisms commonly isolated from patient specimens. Although these tests do not rule out an occasional misidentification, those errors may not have important consequences with regard to patient outcome. Those situations in which rapid test results may have limitations are described. Unless those exceptions provide clinically useful information, confirmatory identification need not be done.