Gram-negative bacterial infection

Gram-negative bacterial infection

Gram-negative bacterial infection
Classification and external resources
Gram negative cell wall
MeSH D016905

Gram-negative bacterial infection refers to a disease caused by Gram-negative bacteria. One example is E. coli.[1]

It is important to recognize that this class is defined morphologically (by the presence of a bacterial outer membrane), and not histologically (by a pink appearance when stained), though the two usually coincide.

One reason for this division is that the outer membrane is of major clinical significance: it can play a role in the reduced effectiveness of certain antibiotics,[2] and it is the source of endotoxin.[3]

The gram status of some organisms is complex or disputed:

  • Mycoplasma are sometimes considered gram negative,[4][5] but because of its lack of a cell wall and unusual membrane composition, it is sometimes considered separately from other gram negative bacteria.[6]
  • Gardnerella is often considered gram negative,[7] but it is classified in MeSH as both gram positive and gram negative.[8] It has some traits of gram positive bacteria,[9] but has a gram negative appearance.[10] It has been described as a "gram-variable rod".[11][12]


  1. ^ Cordonnier C, Herbrecht R, Buzyn A, et al. (August 2005). "Risk factors for Gram-negative bacterial infections in febrile neutropenia". Haematologica 90 (8): 1102–9.  
  2. ^ Pagès JM, Masi M, Barbe J (August 2005). "Inhibitors of efflux pumps in Gram-negative bacteria". Trends Mol Med 11 (8): 382–9.  
  3. ^ "Introduction: Bacterial Infections: Merck Manual Home Edition". 
  4. ^ Mycoplasma at the US National Library of Medicine Medical Subject Headings (MeSH)
  5. ^ "mycoplasma" at Dorland's Medical Dictionary
  6. ^ Sasaki T (April 1991). "Evidence that mycoplasmas, gram-negative bacteria, and certain gram-positive bacteria share a similar protein antigen". J. Bacteriol. 173 (7): 2398–400.  
  7. ^ "Gardnerella" at Dorland's Medical Dictionary
  8. ^ Gardnerella at the US National Library of Medicine Medical Subject Headings (MeSH)
  9. ^ Sadhu K, Domingue PA, Chow AW, Nelligan J, Cheng N, Costerton JW (July 1989). "Gardnerella vaginalis has a gram-positive cell-wall ultrastructure and lacks classical cell-wall lipopolysaccharide". J. Med. Microbiol. 29 (3): 229–35.  
  10. ^ Cook RL, Reid G, Pond DG, Schmitt CA, Sobel JD (September 1989). "Clue cells in bacterial vaginosis: immunofluorescent identification of the adherent gram-negative bacteria as Gardnerella vaginalis". J. Infect. Dis. 160 (3): 490–6.  
  11. ^ "eMedicine - Gardnerella : Article by Diana Curran". Retrieved 2008-12-07. 
  12. ^ "eMedicine/Stedman Medical Dictionary Lookup!".