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A Gram stain of mixed Staphylococcus aureus (S. aureus ATCC 25923, gram-positive cocci, in purple) and Escherichia coli (E. coli ATCC 11775, gram-negative bacilli, in red), the most common Gram stain reference bacteria. Gram stain (Gram staining or Gram's method), is a method of staining used to classify bacterial species into two large groups ...
Differential staining is a staining process which uses more than one chemical stain. [1] Using multiple stains can better differentiate between different microorganisms or structures/cellular components of a single organism. Differential staining is used to detect abnormalities in the proportion of different white blood cells in the blood.
The Gram stain is used by microbiologists to place bacteria into two main categories, Gram-positive (+) and Gram-negative (-). Gram-positive bacteria have a thick layer of peptidoglycan within the cell wall, and Gram-negative bacteria have a thin layer of peptidoglycan. Gram-positive bacteria take up the crystal violet stain used in the test ...
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.
A Ziehl–Neelsen stain is an acid-fast stain used to stain species of Mycobacterium tuberculosis that do not stain with the standard laboratory staining procedures such as Gram staining. This stain is performed through the use of both red coloured carbol fuchsin that stains the bacteria and a counter stain such as methylene blue .
Specimen adequacy is assessed by the laboratory technologists by examining a Gram stain or cytology stain of the sputum. More than 25 squamous epithelial cells at low power magnification exam under the microscope strongly suggest salivary contamination. [ 3 ]
A Gram stain is performed to show Gram-positive cocci in chains. Then, the organism is cultured on blood agar . The rapid pyrrolidonyl arylamidase (PYR) test is commonly used, wherein a positive reaction confers a presumptive identification of group A beta-hemolytic streptococci if the appearance and clinical context is consistent.
Differentiating Brucella from Salmonella is crucial, as the latter could also be isolated from blood cultures and is Gram-negative. Testing for urease would successfully accomplish the task; it is positive for Brucella and negative for Salmonella. Brucella can also be seen in bone marrow biopsies. Laboratory-acquired brucellosis is common. [20]