Most samples are treated with dyes that stain excitation what this stands out from the background. However, there are also native unstained samples used to fungi, parasites (incl. worm eggs and larvae), so-called vaginal. key cells (Engl. clue cells) (n. d. Talk .: cells, which give an indication of bacterial vaginosis ) and movable microorganisms (z. B. Trichomonas), and syphilis (Treponema spirochetes, using dark field microscopy) detected. DieSichtbarkeit of fungi can be increased to dissolve the surrounding tissue and nichtfungale pathogens by application of 10% potassium hydroxide (KOH).
Microscopy can be carried out rapidly, the accuracy depends on the experience of the examiner and the quality of the equipment. The use of microscopy by physicians outside of certified laboratories is often limited by regulations. Microscopic examination of the tissue may be necessary to distinguish invasive disease of superficial colonization – a distinction is not easy to reach by culture methods. Most samples are treated with dyes that stain excitation what this stands out from the background. However, there are also native unstained samples used to fungi, parasites (incl. worm eggs and larvae), so-called vaginal. key cells (Engl. clue cells) (n. d. Talk .: cells, which give an indication of bacterial vaginosis ) and movable microorganisms (z. B. Trichomonas), and syphilis (Treponema spirochetes, using dark field microscopy) detected. DieSichtbarkeit of fungi can be increased to dissolve the surrounding tissue and nichtfungale pathogens by application of 10% potassium hydroxide (KOH). The clinician calls for a coloring that is based on the most likely pathogens, but no coloring is 100% specific. Most samples are stained by Gram and on acid-fast bacilli when mycobacteria are suspected. However, some pathogens are not easy to detect in these colorations; in suspected these pathogens special stains or other detection methods are needed. Since a microscopic pathogen typically requires an excitation concentration of at least 1 × 104-5 / ml, most samples of body fluids (eg. B. CSF) can be enriched prior to testing (for. Example, by centrifugation). Gram stain Gram stain does the following: Classified bacteria to determine whether they are able to retain crystal violet dye (Gram positive – blue) or not (gram negative – red) Removes the cell shape (eg rods or cocci.) And the cell array (eg . B. clusters, chains, diploid) produces. These characteristics may be groundbreaking for antibiotic therapy before the final identification of the pathogen is fixed. The search for a mixture of microorganisms with a plurality of morphology and staining characteristics on Gram staining is indicative of a contaminated sample or polymicrobial bacterial infection. To carry out a Gram stain, technicians heat-fix the specimen material on a slide and color it successively with crystal violet, Lugol iodine-containing solution (fixation), alcohol (decolorization) and counterstaining (usually Safranin). Staining for acid fast bacilli and modified acid-fast bacilli These dyes are used for the detection of the following: Acid-resistant organisms (Mycobacterium sp) Partially acid-resistant bacteria (especially Nocardia sp.) Rhodococcus and related genera oocytes (of some parasites, for example, Cryptosporidium, Cystoisospora [. Isospora] belli) The detection of mycobacteria in sputum requires at least 10,000 excitation / ml; Nevertheless, the sensitivity of the investigation is limited because mycobacteria are often present only at low bacterial counts. In general, several ml of sputum to be decontaminated with sodium hydroxide and concentrated by centrifugation for acid-fast staining. The specificity is better, although some partially acid fast bacteria are difficult to distinguish from mycobacteria. This fluorescence staining dyes permit detection of low bacterial counts (<1 x 104 cells / ml). Examples are acridine orange (bacteria and fungi) auramine-rhodamine, and auramine O (mycobacteria) Calcofluor White (fungi, in particular dermatophytes) The coupling of a fluorescent dye should be of an antibody directed against a microorganism antibody (direct or indirect immunofluorescence) theoretically increase the sensitivity and specificity. However, these tests are difficult to read and interpret, and few (z. B. Pneumocystis and Legionella direct fluorescent antibody tests) are commercially available and widely used. Ink preparation (colloidal carbon): This stain is used in particular for the detection of Cryptococcus neoformans and other bekapselten fungi in a cell suspension (e.g., spinal fluid sediment.). The background is stained to the pathogen so that capsules are visible to the pathogen than Halo. In CSF the test is not as sensitive as the cryptococcal antigen detection. The specificity is limited, leukocytes may appear bekapselt. Warthin-Starry staining and Dieterle staining These silver stains used to visualize bacteria, such as spirochetes Helicobacter pylori microsporidia Bartonella henselae (The cause of cat scratch disease) May-Grunwald stain and Giemsa staining These dyes are used to detect the following: Parasites in the blood Histoplasma capsulatum in phagocytes and tissue cells intracellular inclusions by viruses and chlamydia trophozoites of Pneumocystis jirovecii Some intracellular bacteria trichrome staining (Wheatley Gomori stain) and iron Hämatox Ylin staining These dyes are used for the detection of intestinal protozoa. The Gomori Wheatley staining is used for the detection of microsporidia. This can overlook any worm eggs and larvae, and can not reliably identify Cryptosporidium. Fungi and human cells take up the dye. The iron hematoxylin stain stained cells, cell inclusions and nuclei differently. Worm eggs can turn dark, to allow identification.