darkfield microscopy

darkfield microscopy

Etymology: AS, deorc, hidden, feld, field; Gk, mikros, small, skopein, to look
examination of a microscopic specimen illuminated by a peripheral light source. The illumination causes the specimen to appear to glow against a dark background. In laboratory diagnosis, the technique is used primarily to identify the syphilis spirochete. Also called darkfield illumination, ultramicroscopy.
enlarge picture
Darkfield microscopy: positive examination
References in periodicals archive ?
Darkfield microscopy or staining with acridine orange might be required to increase sensitivity.
The researchers used several methods for examining the cultures for spirochetes including light and darkfield microscopy, silver staining, immunohistochemical staining, molecular hybridization, and PCR analysis.
Darkfield microscopy is not utilized to a great extent today in hospital microbiology laboratories.
Among the topics are light and color, diffraction and spatial resolution, phase contrast microscopy and darkfield microscopy, the fluorescence imaging of dynamic molecular processes, super-resolution imaging, and digital image processing.
fluorescence, phase contrast, and darkfield microscopy.
A CONFIRMED CASE of congenital syphillis is an infant in whom Treponema pallidum is identified by darkfield microscopy, fluorescent antibody, or other specific stains in specimens from lesions, placenta, umbilical cord, or autopsy material.
By 1950 Germans identified Borrelia in blood form by darkfield microscopy and gave Penicillium to the sick and they recovered, if not always forever.
The US Centers for Disease Control and Prevention (CDC) recently updated the definitions for confirmed cases of primary and secondary syphilis and now considers Treponema pallidum PCR (Tp-PCR) to be a valid diagnostic method along with darkfield microscopy (DFM) (2), which is still considered the reference test (although it remains imperfect) (3).
Direct methods include darkfield microscopy, molecular assays to detect T pallidum DNA, and histopathologic examination of biopsies of skin or mucous membranes (which can also provide indirect evidence of infection, on the basis of patterns of inflammation in the tissue).
The Circular Differential Interference Contrast (C-DIC) technique uses circularly polarized light to solve insufficient contrast problems observed in classical brightfield and darkfield microscopy.
Although this may seem obtuse at first consideration, Enderlein observed through darkfield microscopy from 1900 through the 1950s that we have symbionts or endobionts in our blood and tissues which are pleomorphic.