Definitions for gram-negative bacteria
gram-neg·a·tive bac·te·ri·a

WikipediaRate this definition:0.0 / 0 votes

1. Gram-negative bacteria

   Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall sandwiched between an inner cytoplasmic cell membrane and a bacterial outer membrane. Gram-negative bacteria are found in virtually all environments on Earth that support life. The gram-negative bacteria include the model organism Escherichia coli, as well as many pathogenic bacteria, such as Pseudomonas aeruginosa, Chlamydia trachomatis, and Yersinia pestis. They are a significant medical challenge as their outer membrane protects them from many antibiotics (including penicillin), detergents that would normally damage the inner cell membrane, and lysozyme, an antimicrobial enzyme produced by animals that forms part of the innate immune system. Additionally, the outer leaflet of this membrane comprises a complex lipopolysaccharide (LPS) whose lipid A component can cause a toxic reaction when bacteria are lysed by immune cells. This toxic reaction may lead to low blood pressure, respiratory failure, reduced oxygen delivery, and lactic acidosis – manifestations of septic shock.Several classes of antibiotics have been designed to target gram-negative bacteria, including aminopenicillins, ureidopenicillins, cephalosporins, beta-lactam-betalactamase inhibitor combinations (e.g. piperacillin-tazobactam), Folate antagonists, quinolones, and carbapenems. Many of these antibiotics also cover gram-positive organisms. The drugs that specifically target gram-negative organisms include aminoglycosides, monobactams (aztreonam) and ciprofloxacin.

WikidataRate this definition:5.0 / 1 vote

1. Gram-negative bacteria

   Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color. This is because of the existence of an outer membrane preventing the penetration of the stain. The test itself is useful in classifying two distinct types of bacteria based on the structural differences of their bacterial cell walls. Gram-positive bacteria will retain the crystal violet dye when washed in a decolorizing solution. Compared with Gram-positive bacteria, Gram-negative bacteria are more resistant against antibiotics, because of their relatively impermeable cell wall. The pathogenic capability of Gram-negative bacteria is often associated with certain components of Gram-negative cell envelope, in particular, the lipopolysaccharide layer. In humans, LPS triggers an innate immune response characterized by cytokine production and immune system activation. Inflammation is a common result of cytokine production, which can also produce host toxicity. The innate immune response to LPS, however, is not synonymous with pathogenicity, or the ability to cause disease in humans.

U.S. National Library of MedicineRate this definition:3.0 / 1 vote

1. Gram-Negative Bacteria

   Bacteria which lose crystal violet stain but are stained pink when treated by Gram's method.

How to pronounce gram-negative bacteria?

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Numerology

1. Chaldean Numerology

   The numerical value of gram-negative bacteria in Chaldean Numerology is: 5

2. Pythagorean Numerology

   The numerical value of gram-negative bacteria in Pythagorean Numerology is: 1

References

1. ^ Wikipedia
   https://en.wikipedia.org/wiki/Gram-Negative_Bacteria
2. ^ Wikidata
   https://www.wikidata.org/w/index.php?search=gram-negative bacteria