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Detection of infection or infectious agents by use of cytologic and histologic stains
1Department of Pathology, University of Texas Medical Branch, Galveston, 77555-0743, USA.
Abstract:
A wide variety of stains are useful for detection of different organisms or, for viruses, the cytopathologic changes they induce, in smears prepared directly from clinical specimens and in tissue sections. Other types of stains, such as hematoxylin and eosin, are used routinely to stain tissue sections and are most valuable for assessing the immunologic response of the host to the invading pathogen. In many cases, the pattern of inflammation provides important clues to diagnosis and helps to guide the selection of additional "special" stains used predominantly for diagnosis of infectious diseases. A stain may be nonspecific, allowing detection of a spectrum of organisms, as do the Papanicolaou stain and silver impregnation methods, or detection of only a limited group of organisms, as do the different acid-fast techniques. Some nonspecific stains, such as the Gram stain, are differential and provide valuable preliminary information concerning identification. Immunohistochemical stains, on the other hand, are specific for a particular organism, although in some cases cross-reactions with other organisms occur. Despite the wealth of information that can be gleaned from a stained smear or section of tissue, however, the specific etiology of an infection often cannot be determined on the basis of only the morphology of the organisms seen; culture data are essential and must be considered in the final diagnosis.
Insights
Various stains aid in detecting infectious organisms and host responses in clinical specimens. While some stains are broad-spectrum, others are specific, but definitive diagnosis often requires correlating stain results with culture data.
Area of Science:
- Medical Microbiology
- Histopathology
- Diagnostic Pathology
Background:
- Stains are crucial for identifying microorganisms and host immune responses in clinical samples.
- Routine stains like hematoxylin and eosin assess inflammation, guiding the use of special stains for infectious diseases.
Purpose of the Study:
- To review the utility of various staining techniques in diagnosing infectious diseases.
- To highlight the complementary roles of different stains and culture methods.
Main Methods:
- Discussion of nonspecific stains (e.g., Papanicolaou, silver impregnation, Gram stain) for broad or differential organism detection.
- Explanation of specific stains (e.g., acid-fast, immunohistochemical) for targeted pathogen identification.
- Emphasis on integrating histopathology findings with clinical and microbiological data.
Main Results:
- Nonspecific stains detect a range of organisms or cytopathic effects, while differential stains offer preliminary identification.
- Specific stains target particular pathogens, though cross-reactivity can occur.
- Inflammation patterns in tissue sections provide diagnostic clues.
Conclusions:
- Staining methods offer valuable diagnostic information for infectious diseases, ranging from broad organism detection to specific pathogen identification.
- The interpretation of stained smears and tissue sections is enhanced by understanding inflammation patterns.
- Definitive diagnosis of infection requires correlating staining results with clinical presentation and essential culture data.