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Gram-negative bacterial infection

Gram-negative bacterial infection
Gram negative cell wall.svg
Gram-negative cell wall
SpecialtyInfectious disease Edit this on Wikidata

A gram-negative bacterial infection is a disease caused by gram-negative bacteria such as E. coli.[1]

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. PMID 16079110.
  2. ^ Pagès JM, Masi M, Barbe J (August 2005). "Inhibitors of efflux pumps in Gram-negative bacteria". Trends Mol Med. 11 (8): 382–9. doi:10.1016/j.molmed.2005.06.006. PMID 15996519.
  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. doi:10.1128/jb.173.7.2398-2400.1991. PMC 207793. PMID 2007558.
  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. doi:10.1099/00222615-29-3-229. PMID 2787405.
  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. doi:10.1093/infdis/160.3.490. PMID 2668431.
  11. ^ "eMedicine - Gardnerella : Article by Diana Curran". Retrieved 2008-12-07.
  12. ^ "eMedicine/Stedman Medical Dictionary Lookup!".[permanent dead link]

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