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.

Many laboratories use commercial systems for identification of microorganisms, because the laboratories lack the confidence in or resources for performing in-house validations of alternative methods. Use of commercial panels has resulted in greater standardization and more accurate taxonomic identifications, albeit at relatively higher cost and slower turnaround time. This document provides well-documented, published studies to guide laboratories in choosing rapid, reliable, and often less expensive alternatives to commercial systems. This guideline shares the experience and expertise of practicing microbiologists for reporting bacterial and yeast identifications more rapidly than by traditional methods.