Gram-negative bacterial infection

Gram-negative bacterial infection
Gram negative cell wall
Classification and external resources
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]

References

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. 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!".