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Topic: Gram-negative

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Gram-negative - Wikipedia, the free encyclopedia In testing for a gram stain, a counterstain is added after the crystal violet, which colors all gram-negative bacteria a red or pink color. Gram positive bacteria will retain the dark blue dye after an alcohol wash, but gram negative do not. The test itself is useful in classifying two distinctly different types of bacteria based on structural differences. www.sciencedaily.com /encyclopedia/gram_negative   (439 words)

AllRefer Health - Gram Negative Meningitis (Gram-Negative Meningitis) Gram-negative meningitis is an infection of the membranes covering the brain and spinal cord (meninges) caused by gram-negative bacteria (bacteria that turn pink when exposed to a special stain). Bacteria causing gram negative meningitis include Pseudomonas aeruginosa, Escherichia coli, Enterobacter aerogenes, Proteus morganii, and Klebsiella pneumoniae. Acute bacterial meningitis, which can be caused by gram-negative bacteria, is very serious and should be treated immediately to prevent permanent damage. health.allrefer.com /health/meningitis-gram-negative-info.html   (402 words)

Gram-negative - Wikipedia, the free encyclopedia Bacteria that are Gram-negative are not stained dark blue or violet by Gram staining, in contrast to Gram-positive bacteria. The difference lies in the cell wall of the two types; in contrast to most Gram-positive bacteria, Gram-negative bacteria have only a few layers of peptidoglycan and a secondary cell membrane made primarily of lipopolysaccharide. Two major subclassifications of Gram-negative bacteria are Gram-negative cocci and Gram-negative rods (bacilli), which they owe to their appearance under a microscope. en.wikipedia.org /wiki/Gram-negative   (402 words)

Learn more about Gram staining in the online encyclopedia. Gram negative bacteria have a thin cell wall made of a layer of peptidoglycan surrounded by an outer membrane containing lipids. As a rule of thumb (which has exceptions), Gram-negative bacteria are more dangerous as disease organisms, because their outer membrane acts as "camouflage"; the human body does not contain peptidoglycan and in fact produces an enzyme called lysozyme which attacks the open peptidoglycan layer of Gram-positive bacteria. Opinions vary as to the best choice but suitable stains include safranin or fuchsin.This stains the gram negative organisms. www.onlineencyclopedia.org /g/gr/gram_staining.html   (402 words)

Bite Sized tutorials, the gram stain The most significant from a clinical point of view is the gonococcus, Neisseria gonorrhoea which typically appears as a Gram-negative diplococcus looking very much like a pair of kidney bean. This is achieved by treating the smear with a compound which stains the Gram-negative cells a colour which contrasts markedly with the blue-black colour of the Gram-positive cells. Gram's Stain is a widely used method of staining bacteria as an aid to their identification. www.ncl.ac.uk /dental/oralbiol/oralenv/tutorials/gramstain.htm   (402 words)

Gram-positive - Wikipedia, the free encyclopedia Gram-positive bacteria are those that are stained dark blue or violet by gram staining, in contrast to gram-negative bacteria, which are not affected by the stain. The actinobacteria are another major group of gram-positive bacteria; they and the Firmicutes are referred to as the high and low G+C groups based on the guanosine and cytosine content of their DNA. It has also been expanded to include the Mollicutes, bacteria like Mycoplasma that lack cell walls and so cannot be stained by Gram, but are derived from such forms. en.wikipedia.org /wiki/Gram-positive   (402 words)

Gram Stain Kit and Reagents The effect of decolorizer on Gram positive bacteria is to dehydrate them, decreasing the cell wall permeability and increasing the retention of the crystal violet iodine complex presence, and Gram negative bacteria appearing to stain pink red due to the staining from the Safranin counterstain. The difference in staining reaction between Gram positive and negative bacteria is attributed to the distinctive chemistry and physical structure of the cell walls of these organisms. Certain antibacterial drugs can render Gram positive bacteria Gram negative. www.butlersalesassociates.com /VoluSol/gram_stain_kit_and_reagents.htm   (402 words)

Bacteria The cell walls of gram-negative bacteria have a very low affinity for the violet stain, which is rinsed out by the alcohol. Gram positive cell walls are about five times as rich in peptidoglycan as gram-negative cell walls. To gram stain, an investigator smears a sample of bacteria on a slide, soaks it in a violet dye and then treats it with iodine. fig.cox.miami.edu /Faculty/Dana/gram.html   (402 words)

NCDA&CS - Agricultural Statistics Division Shigella - genus of Gram-negative, anaerobic, rod-shaped bacteria. Campylobacter - genus of Gram-negative bacteria found in the intestinal tract and reproductive organs of animals and the intestinal tract of humans. modifying the immune response, in a negative way, so it will have a diminished reaction to a foreign substance. www.ncagr.com /cyber/kidswrld/foodsafe/badbug/define.htm   (402 words)

Gram-Negative bacteria & Endotoxemia Bacteria are classified as either gram-positive or gram-negative, based on their cell-wall characteristics and uptake (either positive or negative) of Gram's stain. Endotoxin is not secreted by bacteria, but instead is a component of the bacterial cell wall of gram-negative bacteria and is considered to be one of the most injurious and fatal components of gram-negative bacteria. Millions of gram-negative bacteria are normally present in the intestine of animals. www.saanendoah.com /gramneg.html   (402 words)

Gram Negative Unknown for Microbiology The experiment has two parts and this is the part of isolating the gram-negative bacteria. The test was conducted and the bacteria was found to be oxidase negative which means that it does not contain the enzyme cytochrome oxidase and means that it is a fermentative facultative anaerobe according to the flow chart. The unknown bacteria grew on the slant and turned the media blue signifying that it is positive for the use of citrate as a carbon source in the absence of glucose and lactose. www.angelfire.com /sc/arnoldj/gramneg.html   (402 words)

Gram negative Emergence of resistance in gram-negative bacteria during therapy with expanded-spectrum cephalosporins ; Dworzack DL et al.; To assess the clinical importance of emergence of beta-lactam resistance caused by stable derepression of chromosomal beta-lactamases, sequential cultures from patients treated with expanded-spectrum cephalosporins were monitored for the persistence of bacteria possessing these enzymes. bacteria from raw baled cotton and synthetic textile fibers with special reference to environmental GNB and endotoxin concentrations of textile mill ; Gokani VN et al.; The objective of this study was to examine the gram-negative bacterial (GNB) content of Indian raw baled cotton fibers and to compare with the U.S. There was one false-negative specimen, giving an overall sensitivity of 97.3% and a negative predictive value of 99.9%. www.bionewsonline.com /i/2/gram_negative_j.htm   (402 words)

Gram Positive and Negative Bacteria In Gram negative bacteria, the peptidoglycan is still outside of the inner membrane, but now there is a more complex outer membrane present. Both Gram positive and negative bacteria contain peptidoglycan in the cell wall, but in the Gram negative, various other layers protect it and so the stain cannot reach it to cause the colouration. Bacteria can be differentiated into Gram positive or Gram negative by testing them with the “Gram stain”. homepage.ntlworld.com /diamonddove/04a_Gram/Gram.htm   (402 words)

Structure and Function of Procaryotes Gram-negative bacteria may contain a single monomolecular layer of murein in their cell walls while Gram-positive bacteria are thought to have several layers or "wraps" of peptidoglycan. In Gram-positive bacteria, peptidoglycans may vary in the amino acid in place of DAP or L-lys in position 3 of the tetrapeptide, and in the exact composition of the interpeptide bridge. One idea is that they provide a channel of regularly-oriented negative charges for threading positively charged substances through the complicated peptidoglycan network. textbookofbacteriology.net /structure.html   (402 words)

Meningitis - gram-negative Gram-negative meningitis is an infection of the membranes covering the brain and spinal cord (meninges) caused by gram-negative bacteria (bacteria that turn pink when exposed to a special stain). Acute bacterial meningitis, which can be caused by gram-negative bacteria, is very serious and should be treated immediately to prevent permanent damage. It is important to recognize the symptoms of this kind of meningitis and seek treatment as soon as possible to prevent serious illness or death. www.dental.am /more.php?id=12355_0_14_0_M230   (402 words)

Bacteria Bacteria that are not decolorized by the alcohol/acetone wash are gram-positive. Although the Gram stain might seem an arbitrary criterion to use in bacterial taxonomy, it does, in fact, distinguish between two fundamentally different kinds of bacterial cell walls and reflects a natural division among the bacteria. They are probably the descendants of gram-positive bacteria who have lost much of their genome — now depending on the gene products of their host. users.rcn.com /jkimball.ma.ultranet/BiologyPages/E/Eubacteria.html   (402 words)

Gram Stain In Gram-negative bacteria, the outer membrane prevents the stain from reaching the peptidoglycan layer in the periplasm. In Gram-positive bacteria, the purple crystal violet stain is trapped by the layer of peptidoglycan which forms the outer layer of the cell. In 1884, Hans Christian Gram, a Danish doctor working in Berlin, accidentally stumbled on a method which still forms the basis for the identification of bacteria. www-micro.msb.le.ac.uk /video/Gram.html   (402 words)

Rapid Method for Detection of Gram-Positive and -Negative Bacteria in Milk from Cows with Moderate or Severe Clinical Mastitis -- Yazdankhah et al. 39 (9): 3228 -- Journal of Clinical Microbiology A rapid method for demonstration of gram-positive and gram-negative bacteria in milk is described. The analytical technique developed in this study was applied to gram-negative and gram-positive bacteria (both cocci and rods) Gram characterisation determined on single cells and the microcolony level of bacteria immobilized on polycarbonate membrane filters. jcm.asm.org /cgi/content/full/39/9/3228   (402 words)

Gram-staining Procedure Gram negative bacteria, however, take on a pink color and are easily distinguishable from the Gram positives. Gram positive cells will incorporate little or no counterstain and will remain blue-violet in appearance. Likewise, not using enough decolorizer may yield a false Gram (+) results. medic.med.uth.tmc.edu /path/grampro.htm   (402 words)

General bacteriology This bacteria is sorbitol negative, glucuronidase negative, no fluorescence. As many bacteria described in Bergey's Manual are not living any more and her description is still incomplete an international community made a general revision of the content of the manual and presented a list denominated as Approved List (Skerman et al.,1980). A rapid growth of coliform bacteria is granted due to the high nourishing properties of the medium and the presence of a phosphate buffer. www.ourfood.com /General_bacteriology.html   (402 words)

Gram negative The liability to infection of preterm and dysmature babies and the role of Gram-negative bacteria in the aetiology of neonatal meningitis is emphasized. Rheumatoid behavior in normal human synovial fibroblasts induced by extracts of Gram-negative bacteria ; Buckingham RB et al.; We have previously shown that exposure of normal human synovial cells to whole extracts of Gram-negative bacteria or purified endotoxins results in increased synthesis of hyaluronic acid, and increased glucose uptake and lactate output. This preliminary study suggests the usefulness of the Limulus assay as an adjunct to bacteriologic cultures in the early detection of significant gram-negative infection in severely malnourished children. www.bionewsonline.com /l/2/gram_negative_m.htm   (402 words)

Dr. Tritz: Bacteria there is a negative exponential phase which results in a decrease in the numbers of bacteria within the system. The capsule of bacteria may be penetrated by structures arising from the cell wall or plasma membrane such as cell wall specific polysaccharide, cell wall teichoic acid, plasma membrane lipoteichoic acid, flagella and pili. Not all bacteria form capsules but in those that do the capsule is the interface between the bacterial cell and the external environment. www.kcom.edu /faculty/chamberlain/Website/Lects/Bacteria.htm   (402 words)

Bacteria They include the gliding bacteria, the spirochetes, the curved ( vibrios) and spiral ( spirillae) bacteria, gram-negative rods, gram-negative cocci, rickettsias, chlamydias and the photosynthetic cyanobacteria. About 75% of known eubacteria are gram negative. For many years, the evolutionary relationships of bacteria were so poorly understood that they were classified only on the basis of their shape and staining characteristics. fig.cox.miami.edu /Faculty/Dana/monera.html   (402 words)

Prokaryotic Cell Structure: The Gram Negative Cell Wall As mentioned in the previous section on peptidoglycan, gram-negative bacteria are those that decolorize during the Gram stain procedure, pick up the counterstain safranin, and appear pink. Animation showing the release of LPS from the cell wall of a gram negative bacterium and its subsequent binding to pattern-recognition receptors on a macrophage. Prokaryotic Cell Structure: The Gram Negative Cell Wall www.cat.cc.md.us /courses/bio141/lecguide/unit1/prostruct/gncw.html   (402 words)

Structures of Gram-Negative Cell Walls and Their Derived Membrane Vesicles -- Beveridge 181 (16): 4725 -- The Journal of Bacteriology Gram-negative bacteria produce membrane vesicles which are capable of killing other bacteria. Outer membranes of gram-negative bacteria are permeable to steroid probes. Intuitively, MVs are not a brand-new structural device for gram-negative bacteria. jb.asm.org /cgi/content/full/181/16/4725   (402 words)

Gram Positive Bacteria While in Gram-negative bacteria the peptidoglycan is simple in structure and comparatively uniform throughout most genera, in Gram-positive bacteria there is a very big variation in structure and composition. GRAM-POSITIVE BACTERIA are characterised by having as part of their cell wall structure peptidoglycan as well as polysaccharides and/or teichoic acids. THE LIPOPOLYSACCHARIDES of the Gram-positive bacteria have not been extensively studied apart from those of the streptococci, where they are the basis of their serological subdivision. www.microbionet.com.au /grampositivebacteria.htm   (402 words)

Emerging Antimicrobial Resistance in Gram Negative Bacteria There are two major classes of bacteria, which are identified by the response of the bacterial cell wall to a staining procedure using with gentian violet dye. Furthermore, bacteria with the potential for causing epidemic disease, especially in countries where sanitation is poor, have shown significant antibiotic resistance. This is particularly important within hospitals, where antibiotic-resistant bacteria are more prevalent than in the outside community and where bacterial spread from patient to patient is facilitated by carriage on the hands of staff. www.termpapergenie.com /runninghead.html   (402 words)

available technologies Compounds sensitize the bacteria by effectively permeabilizing the outer membranes of Gram-negative bacteria to antibiotics, such as erythromycin, novobiocin and rifampin. Antibiotics for Gram-Negative Bacteria - This family of compounds, cationic steroid antibiotics, are effective against Gram-negative bacteria at very low concentrations. The biologic activities can be manipulated by altering the length and nature of the side chains as well as the terminal functional group. techtransfer.byu.edu /techabstracts/antibioticsgramnegative.htm   (402 words)

The problem with gram-negative bacteria Reptile bites are often more difficult to resolve than herp herp keepers and their physicans realize because of the presence of gram-negative as well as gram-positive bacteria in the reptile's mouth, which then gets transfered into the bite wound. The distinctive feature of gram-negative bacteria is the presence of a double membrane surrounding each bacterial cell. Although all bacteria have an inner cell membrane, gram-negative bacteria have a unique outer membrane. www.anapsid.org /gramnegative.html   (402 words)

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