Direct microscopic examination of clinical specimens for the laboratory diagnosis of fungal infections

Abstract

The question of which stain or procedure to use for the detection of fungal elements is one that can be resolved by personal preference and user experience. All procedures require technologists to remember that specimens may contain any number of bacterial, fungal, or other etiologic agents. To “think microbiology” when looking at any type of direct examination will lead to better detection rates. Advances continue to be made in the area of rapid and direct detection of fungi in clinical specimens. Molecular techniques such as DNA probes, in situ hybridization, and the polymerase chain reaction are currently being evaluated in several reference laboratories. These techniques are shown to have high degrees of sensitivity and specificity. However, they are very specialized and cumbersome test that require several hours to complete, and will not be readily available to the average mycology laboratory in the near future. Currently, laboratories must rely on the astute powers of observation and inquisitive minds of those performing the work. Calcofluor white appears to enhance the detection of fungal elements due to its staining properties. Laboratories will find that investing in a fluorescent microscope and approproate filters will yield better patient care.