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Gram stain (Gram staining or Gram's method), is a method of staining used to classify bacterial species into two large groups: gram-positive bacteria and gram-negative bacteria. It may also be used to diagnose a fungal infection. [1] The name comes from the Danish bacteriologist Hans Christian Gram, who developed the technique in 1884. [2] Gram ...
Mycoplasma species are often found in research laboratories as contaminants in cell culture. Mycoplasmal cell culture contamination occurs due to contamination from individuals or contaminated cell culture medium ingredients. [34] Mycoplasma cells are physically small – less than 1 μm, so are difficult to detect with a conventional microscope.
Hans Christian Joachim Gram (13 September 1853 – 14 November 1938) was a Danish bacteriologist noted for his development of the Gram stain, still a standard technique to classify bacteria and make them more visible under a microscope.
Colonial morphology serves as the first step in the identification of microbial species from clinical samples. [10] Based on the visual appearance of the colonies, microbiologists can narrow down the list of possible organisms, allowing them to select appropriate tests to provide a definitive diagnosis.
Mycoplasma hominis, a microorganism without a cell wall, is difficult to detect because it cannot be identified through Gram staining. [16] Culturing it is demanding and time-consuming due to specialized requirements and while direct DNA testing is an option, it's not always highly sensitive, and not all labs possess its capabilities. [ 17 ]
Other bacteria are commonly identified with a microscope by staining them with Gram stain. However, the mycolic acid in the cell wall of M. tuberculosis does not absorb the stain. Instead, acid-fast stains such as Ziehl–Neelsen stain, or fluorescent stains such as auramine are used. [4]
Mycoplasma gallisepticum (MG) is a bacterium in the class Mollicutes and the family Mycoplasmataceae. It causes chronic respiratory disease (CRD) in chickens and infectious sinusitis in turkeys, chickens, game birds, pigeons, and passerine birds of all ages. [1] [2] Mycoplasma gallisepticum is a significant pathogen in poultry.
All gram-positive bacteria are bounded by a single-unit lipid membrane, and, in general, they contain a thick layer (20–80 nm) of peptidoglycan responsible for retaining the Gram stain. A number of other bacteria—that are bounded by a single membrane, but stain gram-negative due to either lack of the peptidoglycan layer, as in the ...