Question

What is the difference between a Gram + and Gram – cell? Which type is more resistant to treatment? Please explain

Answer 1

Gram positive and gram negative bacteria are classified on the basis of a concept called GRAM'S Staining. Gram negative bacteria are more resistant towards antibiotics as compared to gram positive bacteria.

Gram positive bacteria have a cell membrane surrounded by a thick peptidoglycan layer which forms the cell wall of the bacteria. It protects the bacteria from mechanical and physical damages and also by the antibiotics. The cell wall also contains teichoic acids. Antibotics also are not known to kill the gram positive bacteria completely but they rather break or weaken the NAM-NAG linkages that are present in the murein cell wall. If the linkages weaken then definitely the bacteria is susceptble to further damage and death by any other reason.

The gram negative bacteria had a cell wall surrounding the cell membrane but the structure of the cell wall is what makes it different from gram positive bacteria. It has a thin layer of peptidoglycan instead of the usual thick layer of peptidoglycan in the gram positive bacteria. Cell wall here lacks teichoic acids but the peptidoglycan layer is surrounded further by the lipopolysaccharides (LPS) lipoproteins and phospholipids. Thin peptidoglycan layer aids in easily mechanical damage that can be brought upon the bacteria however, presence of lipoproteins makes the bacteria less susceptible to damage by antibodies and dyes etc. Lipopolysaccharides act as an endotoxin and excludes most of the antibiotics from the inner cell which makes gram negative bacteria more resistant than gram positive bacteria.