|
Gram-Positive Bacteria |
Feature |
Gram-Negative Bacteria |
|
Absent |
Outer Membrane |
Present |
|
Thick (50-100 layers) |
Cell Wall Thickness |
Thin (1-2 layers) |
|
Thick and multilayered • L-lysine • Pentaglycin bridge • Present |
Peptidoglycan Layer- • 3rd position of tetra peptide • Penta glycine bridge • NAG-NAM |
Thin • Meso di amino pimelic acid (DAP) • Absent • Present |
|
• Techoic acid • X • Lipoprotein • Peptidoglycans |
Composition |
• X • Lipopoly saccharide (LPS) • Lipoprotein • Peptidoglycan |
|
Low (2-5%) |
Lipid Content |
High (15-20%) |
|
Absent |
Periplasmic Space |
Present |
|
Absent |
Porins |
Present in the outer membrane |
|
Retain crystal violet dye (purple) |
Staining with Gram Stain |
Do not retain crystal violet |
|
Generally more susceptible |
Susceptibility to Penicillin |
Generally less susceptible |
|
Primarily exotoxins |
Toxins Produced |
Endotoxins and exotoxins |
|
• Staphylococcus • Streptococcus |
Example Organisms |
• Escherichia coli • Salmonella |