Rapid Methods For Organism Identification

Lab Guidelines
Do It Quick! Using Rapid Methods for Organism Identification
Approved CLSI Guideline Facilitates the Identification of Major Pathogens
DOI: 10.1309/LM8PX35YWNKYSFIM

& Standards

for information on organisms such as Neisseria gonorrhoeae and Neisseria meningitidis. “The rapid tests are just as accurate for these organisms as are the more time-consuming, overnight tests, andpatients benefit greatly from timely initiation of appropriate therapy,” remarked Dr. York. Proven Accuracy Using rapid techniques, both bacteria and yeast can be identified either to genus or genus and species with a high degree of certainty. The majority of the testing can be performed within two hours after obtaining a pure microbial colony. The guideline delineates phenotypic and biochemicaltests that provide results comparable to more elaborate, definitive, time-consuming test panels and provides decision criteria for continuing on to more definitive testing. “The beauty of these rapid methods is two-fold: one, the clinician receives a microbial identification one day earlier and can treat patients sooner; and, two, the clinician can rule in or rule out potential bioterrorism threatsand notify appropriate public health authorities earlier,” said Dr. Baron. The accuracy of these tests is very high—greater than 95%—but variable based on organism. For instance, a validation procedure determined that the rapid identification of Escherichia coli described in the guideline was 99% accurate and was equal to or better at identification than commercial test methods. Dr. Yorkreiterated the importance of this document: “People are not aware that rapid testing provides very accurate results. This guideline was created because many laboratorians think rapid tests are only presumptive. To the contrary, many of these rapid tests are as accurate as tests performed with expensive identification kits.” Wide Applicability and Diverse Interests The guideline has broad applicability,ranging from large microbiology laboratories to the mission field in developing countries. “This guideline is especially valuable to resource-constrained countries where microbial identification test kits may not be available, mainly due to the expense,” remarked Dr. York. Wherever laboratory testing is performed, “all laboratory technicians and technologists should be competent in recognizingcolony morphology, proper Gram stain description, and discerning characteristic odors,” said Dr. Baron. “These rapid tests are nonwaived tests and highly dependent on the skill and experience of the technologist performing the tests.” Laboratory supervisors need to determine the technical competency of each person performing these procedures. Updates and Content Expansion “This guideline was so wellreceived at first publication that this update is expected to be even more popular,” noted Dr. York. M35-A2 was reorganized for ease of use. The biochemical tests are alphabetized. Organisms not well-identified by commercial test systems were also included. 213

In the clinical microbiology laboratory, the need for accurate reporting to the clinician of microbial identification is coupled with ademand for rapid turnaround time to allow for initiation of therapy. These requirements often demand the expenditure of resources in a health care environment where laboratory personnel are faced with ever-increasing financial and manpower constraints. The need for cost-effective approaches to diagnostic microbiology may preempt the use of time- and resource-consuming, comprehensive microbialidentification techniques when rapid, less-costly approaches are available and appropriate. Many microorganisms commonly isolated in diagnostic microbiology laboratories exhibit specific morphologic or biochemical traits that can be assessed rapidly upon obtaining a pure colony. Laboratory professionals can use abbreviated methods to quickly and reliably identify organisms with a high degree of...