Gram-Negative Bacteria

A Gram-Negative Bacteria is a bacteria that does not respond to a Gram Test.

• Context:
  • …
• Example(s):
  • Enterobacteriaceae, such as E. Coli.
  • Vibrio Cholerae.
  • Pseudomonas Aeruginosa.
  • Campylobacter Jejuni.
  • Bacteroidota.
  • Haemophilus influenzae.
  • …
• Counter-Example(s):
  • Gram-Positive Bacteria, such as S. pneumoniae.
• See: AmyL.

---

---

References

2009

• (Wikipedia, 2009) ⇒ http://en.wikipedia.org/wiki/Gram-negative
  • Gram-negative bacteria are those bacteria that do not retain crystal violet dye in the Gram staining protocol. [1] In a Gram stain test, a counterstain (commonly safranin) is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color. The test itself is useful in classifying two distinct types of bacteria based on the structural differences of their cell walls. On the other hand, Gram-positive bacteria will retain the crystal violet dye when washed in a decolorizing solution.

    Many species of Gram-negative bacteria are pathogenic, meaning that they can cause disease in a host organism. This pathogenic capability is usually associated with certain components of Gram-negative cell walls, in particular the lipopolysaccharide (also known as LPS or endotoxin) layer. [1] In humans, LPS triggers an innate immune response characterized by cytokine production and immune system activation. Inflammation is a common result of cytokine(from the greek cyto=cell,kinesis=movement) production, which can also produce host toxicity.

---