characteristics of gram negative bacteria

Antibiotics: actions, origins, resistance. As many antibiotics inhibit enzymes important in the assembly of peptidoglycan layer which in Gram-negative bacteria lies between two membranes, many antibiotics that are effective against Gram-positive bacteria are ineffective against Gram-negative bacteria as they cannot go through the outer membrane and access the peptidoglycan layer inside the cell envelope. Gram-negative bacterial cell walls are more complex than Gram-positive bacterial cell walls as the former possess two membranes and their outer membrane contains porin proteins that limit the size of molecules entering the cell, therefore, preventing large quantities of antibiotics from entering the cell wall where they would take effect. Gram-negative bacteria cause such infections as pneumonia and septicaemia.

Infections caused by Gram-negative bacteria and treatment implications Do not retain crystal violet dye after the Gram stain test.Porin proteins in the outer membrane limiting the size of molecules entering the cell.A thin layer of peptidoglycan in-between the two membranes.Two membranes (inner and outer) in the cell envelope.The outer membrane of Gram-negative cell walls is porous to ions, contains toxic lipid parts of lipopolysaccharides and has defensive properties. In-between these membranes lies a thin peptidoglycan layer and the aqueous periplasm where various nutrient-transporting enzymes and transporters are found. The cell envelope of Gram-negative bacteria contains two membranes (outer membrane and inner (cell) membrane). 3 Infections caused by Gram-negative bacteria and treatment implicationsĬell wall structure of the Gram-negative bacteria.Gram-negative bacteria stain red when this process is used. Gram-negative bacteria are classified by the color they turn after a chemical process called Gram staining is used on them. Gram-positive organisms stain purple with a differential staining procedure developed in 1884 by. Bacteria are classified by how they appear under the microscope and by other features. 1 Cell wall structure of the Gram-negative bacteria Many have certain distinct cellular characteristics.

Characteristics of gram negative bacteria