Gram Positive vs Gram Negative Bacteria

Gram Positive vs Gram Negative Bacteria

It was in 1884 when Hans Christian Gram, a Danish bacteriologist, devised a test and introduced a dye to the bacteria to check if bacteria had a peptidoglycan wall or simply a mesh-like layer of amino acids and sugars. The same method of "Gram staining" is still in use to distinguish between gram positive and gram negativebacteria. Let's find more about it.

Difference in Gram Positive vs. Gram Negative Reaction
Different types of bacteria have been identified already, but they are classified differently. One way to classify them is to perform Gram staining test to check if they belong to gram positive category or are gram negative bacteria.

During a Gram stain test, bacteria are dyed crystal violet and then are washed with a decolorizing solution. After washing, a counterstain is added, which is usually fuchsine or safranin. This changes Gram-negative bacteria to pink or red, while Gram-positive bacteria maintain their violet dye.

This mainly happens because their difference in the structure of cell walls: there is no outer cell membrane in Gram-negative bacteria; however, the cell wall of Gram-positive bacteria is different and is high in peptidoglycan.

Other Differences Between the Two Types of Bacteria
In the war of gram positive vs. gram negative bacterial, there are some obvious differences. Here is more about it.

	Gram Positive Bacteria	Gram Negative Bacteria
Peptidoglycan layer	Thick, multilayered	Thin, single-layered
Teichoic acids	Present in many	Absent
Periplasmic space	Absent	Present
Lipopolysaccharide (LPS) content	Virtually none	High
Outer membrane	Absent	Present
Flagellar structure	2 rings in basal body	4 rings
Lipid and lipoprotein content	Low	High
Toxins producuts	Primarily exotoxins	Primarily endotoxins
Resistance to physical disruption	High	Low
Susceptibility to anionic detergents	High	Low
Inhibition by basic dyes	High	Low
The intensity of resisting sodium azide	High	Low
The intensity of resistance to drying	High	Low
Cell wall composition	The thickness of cell wall is 20-30 nm, and it is smooth. The wall has 70-80% murein with low lipid content. It also contains teichoic acid.	The thickness of cell wall is 8-12 nm. It is wavy and contains 10-20% murein. It comes in contact with plasma membrane at a few loci. It does not contain techoic acid but lipid content is between 20 and 30%.

Gram Positive vs. Gram Negative: Which Is Worse?
Making a comparison of gram-positive and gram-negative bacteria helps find information about how these bacteria behave. Their structure tells a lot about how hard it is to kill them. Gram-negative bacteria are usually much harder to kill, and here comes more.

The wall of gram positive bacteria is like a heavy, thick wooden fence, whereas the wall of gram-negative bacteria is more like a thin bulletproof Kevlar vest. What it implies is that gram positive bacteria have a thick outer covering, which can absorb foreign material with ease. The membrane of gram-negative bacteria is not thick, but it is still nearly impossible to penetrate.

All in all, gram-positive bacteria have a cell membrane about 20-fold thicker as compared to the protective membrane of gram-negative bacteria. It is due to this particular reason that gram-negative bacteria are a lot more resistant to antibiotics as compared to other types of bacteria with thicker walls.

A List of Gram Positive and Gram Negative Bacteria
When comparing gram positive vs. gram negative bacteria, you can find a long list of both types of them. They are responsible for causing different types of infections and ailments. The following chart will provide you with some information about both gram-positive and gram-negative bacteria.

Gram-Positive Bacteria

Types	Brief Intro
Actinomyces	They are responsible for causing cavities and filamentous respiratory diseases.
Bacillus	They are associated with food Poisoning.
Clostridium	They have different strains responsible for causing food poisoning, Botulism, gas, Gangrene, and Tetanus.
Corynebacterium	They include pleiomorphic C diphteriae.
Enterococcus	They include vancomycin resistant E (VRE) bacteria that are quite resistant to many antibiotics.
Gardnerella	They are associated with vaginities.
Lactobacillus	This genus of bacteria helps form vaginal flora.
Listeria	These are fetal pathogens responsible for newborn Meningitis.
Mycoplasma	This genus of bacteria does not have cell wall and are responsible for walking Pneumonia.
Mycobacterium	They may cause Tuberculosis – M leprae and M tuberculosis are in this genus of bacteria.
Streptococcus	This strain of gram positive bacteria includes S pneumonia, s mutants, and s pyogenes.

Gram-Negative Bacteria

Types	Brief Intro
Bortadella	They are short rod-like organisms and also include B Pertussis, which is an aerobic, pathogenic coccobacillus of the genus Bordetella.
Chlamydia	This small parasitic bacterium is like a virus and is responsible for causing diseases such as Psittacosis, Trachoma, and non-specific urethritis.
Enterobacter	It is from the genus of faculatiely anaerobic, non-spore-forming bacteria and can cause Urinary Tract Infections, soft-tissue infections, septic Arthritis, CNS infection, osteoMyelitis, and more.
Helicobacter	This type of bacteria has rod-like shape and is responsible for Peptic Ulcer.
Klebsiella	This type of bacteria has a rod-like appearance and is responsible for hemorrhagic penumonia.
Neisseria	It colonizes the mucosal surfaces and also includes N meningitides and N Gonorrheae.
Proteus	This rod-shaped bacterium is responsible for causing urinary tract infections.
Pseudomonas	It is a genus ofaerobic gammaproteo bacteriaand demonstrates a great deal of metabolic activity.