Probe technology for the clinical microbiology laboratory.

Molecular-based techniques, such as use of genetic probes, can greatly reduce turnaround time of the identification of some isolates in the clinical microbiology laboratory. For example, culture confirmation of an acid-fast bacillus such as Mycobacterium tuberculosis or Mycobacterium avium-intracellulare by a gene probe can be performed within hours of the isolation of the organism. Conventional methods might require more than 2 to 4 weeks for this identification. Identification of a mold, such as Histoplasma capsulatum, with a gene probe, can be done in less than 24 hours, with minimal growth available; conventional fungal identification takes 1 to 2 weeks or more. Whether a probe is used in the clinical microbiology laboratory depends on a number of factors including accuracy of the probe, cost, commercial availability, and ease of performance. In addition, the relevance of a more rapid result needs to be considered. A gene probe may be more specific than conventional methodologies, and this may increase its advantage. Direct specimen testing with probes is presently hampered by inadequate sensitivities. Prior amplification may decrease this limitation. It is hoped that methods will be available in the near future that provide amplification and probing of clinical specimens for laboratory diagnosis to be made within a short time following specimen collection.