They are micrometers (1µm = 10 -6 m) in size. Gram negative bacteria: Stain red or pink due to retaining the counter staining dye called Safranin.īacteria are very small unicellular microorganisms ubiquitous in nature. Gram positive bacteria: Stain dark purple due to retaining the primary dye called Crystal Violet in the cell wall.Ģ. The Gram stain procedure enables bacteria to retain color of the stains, based on the differences in the chemical and physical properties of the cell wall.ġ. Furthermore, it is also an important step in the screening of infectious agents in clinical specimens such as direct smears from a patient. Once stained, the morphology and arrangement of the bacteria may be observed as well. The bacteria present in an unstained smear are invisible when viewed using a light microscope. It is also a key procedure in the identification of bacteria based on staining characteristics, enabling the bacteria to be examined using a light microscope. The Gram stain is a very important preliminary step in the initial characterization and classification of bacteria. After decolorization step, a counterstain is used to impart a pink color to the decolorized gram-negative organisms. Gram-positive bacteria are not decolorized by alcohol and will remain as purple. Gram-negative bacteria are decolorized by the alcohol, losing the color of the primary stain, purple. The procedure is based on the ability of microorganisms to retain color of the stains used during the gram stain reaction. Gram staining is a differential staining technique that differentiates bacteria into two groups: gram-positives and gram-negatives. The most widely used staining procedure in microbiology is the Gram stain, discovered by the Danish scientist and physician Hans Christian Joachim Gram in 1884. Staining is an auxiliary technique used in microscopic techniques used to enhance the clarity of the microscopic image.Stains and dyes are widely used in the scientific field to highlight the structure of the biological specimens, cells, tissues etc. To understand how the Gram stain reaction affects Gram positive and Gram negative bacteria based on the biochemical and structural differences of their cell walls.To differentiate between the two major categories of bacteria: Gram positive and Gram negative.“ Acinetobacter in Healthcare Settings.” Centers for Disease Control and Prevention. “ Haemophilus influenzae serotype f endocarditis and septic arthritis.” IDCases, vol. “ Molecular pathogenesis of infections caused by Moraxella catarrhalis in children.” Swiss Medical Weekly, 29 Oct.
“ Gonorrhea - CDC Fact Sheet (Detailed Version).” Centers for Disease Control and Prevention.īernhard, Sara, et al. “ Pathogenesis of Meningococcemia.” Cold Spring Harbor Perspectives in Medicine, vol. “ Endotoxin Elimination in Patients with Septic Shock: An Observation Study.” Archivum Immunologiae Et Therapiae Experimentalis, vol. “ Group A Streptococcal (GAS) Disease.” Centers for Disease Control and Prevention.Īdamik, Barbara, et al. “ Methicillin-Resistant Staphylococcus Aureus (MRSA).” Centers for Disease Control and Prevention. “ Bacterial Biofilm Formation on Implantable Devices and Approaches to Its Treatment and Prevention.” Heliyon, vol.
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