Detection of infection or infectious agents by use of cytologic and histologic stains

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.

Evaluation of the detection of melanin by the Fontana-Masson silver stain in tissue with a wide range of organisms including Cryptococcus

“…Although the cases of paracoccidioidomycosis and rhinosporidiosis showed only focal staining, infections caused by other organisms showed a very high (≥90%) percentage of organisms staining in at least some cases. Interestingly, although Sporothrix has been reported to be FMS positive [7,13], the one case of sporotrichosis in our study was negative.…”

“…It has been suggested that the stain is relatively specific for infections caused by Cryptococcus neoformans. In fact, this notion has become very prevalent in the peer-reviewed literature [3,[7][8][9][10][11][12][13] as well as textbooks [14][15][16][17]. The idea of a specific stain is appealing because the morphology of Cryptococcus can overlap with that of other organisms, especially when capsular stains (eg, mucicarmine) are negative.…”

Visualization of Mycobacterium avium in Crohn's tissue by oil-immersion microscopy

“…However, to be sure we detected all organisms present, we did not use granulomas to performed a guided search for mycobacteria [24], because organisms in paucibacillary MAP disease of ruminants and tuberculoid leprosy of humans are not confined to granulomas [25e29]. Applying the threshold of 10 positive fields, nearly one-half of CD patients were negative, indicating either the absence of mycobacteria or a bacterial burden less than 10 bacilli per milligram of tissue [12].…”

More experiences with the Tzanck smear test: Cytologic findings in cutaneous granulomatous disorders

“…Fungi may also be detected in smears stained with special stains such as acridine orange, PAS stain, and Gomori methenamine silver. 21 Fungi, such as Candida and Aspergillus species, and the zygomyces (Mucor) can often be identified according to the morphological characteristics of their hyphae. Aspergillosis is an uncommon opportunistic fungal infection caused by a variety of species of which A fumigatus and A niger are the common ones.…”