Needle in a haystack: the new world of diagnostics for micro-organisms

Abstract

Infectious disease diagnostics from tissue specimens has relied upon either the presence of a tissue reaction specific to an infection type or morphological identification of an organism for the last century or more. Molecular diagnostics (the detection of RNA or DNA) from a micro-organism in a sample offers the promise of ultra-sensitive testing for patient care but requires careful selection and use for each patient. Examples of successful approaches include confirmation of species of mycobacteria in AFB-positive case using consensus primers and sequencing, confirmation of species of fungi in sections showing fungal forms using consensus primers and sequencing, and organism specific confirmatory PCR on suspicious lesions. Similarly, clinical laboratory panels for GI pathogens and respiratory pathogens are growing in popularity for rapid screening and accurate diagnosis across a range of organisms. As with cancer diagnostics, one of the next phases of microorganism detection will be for the expression profile or pattern of specific genes which not only identify the organism but provide information on drug resistance, behavior, prognosis, and treatment. A discussion of how these technologies work in basic science are moving into the forefront of patient care will be presented with examples.