Khác biệt giữa bản sửa đổi của “Vi khuẩn Gram âm”

Bỏ phần không được tiếp tục dịch
n (robot Modifie: nl:Gram-negatieve bacteriën)
(Bỏ phần không được tiếp tục dịch)
Trong khi vi khuẩn Gram dương giữ sắc xanh sau khi rửa qua rượu, vi khuẩn gram âm thì không - và hóa sắc đỏ hay hồng.
 
{{đang dịchkhai}}
Many species of Gram-negative bacteria are [[Pathogen|pathogenic]], meaning they can cause disease in a host organism. This pathogenic capability is usually associated with certain components of Gram-negative cell walls, in particular the [[lipopolysaccharide]] (also known as LPS or [[endotoxin]]) layer.
 
==Characteristics==
<!-- Structural diagram here would be helpful-->
The following characteristics are displayed by Gram-negative bacteria:
#Cell walls only contain a few layers of [[peptidoglycan]] (which is present in much higher levels in Gram-positive bacteria)
#Cells are surrounded by an [[outer membrane]] of lipopolysaccharide outside the peptidoglycan layer
#Porins exist in the outer membrane, which act like pores for particular molecules
#There is a space between the layers of peptidoglycan and the secondary cell membrane called the [[periplasmic space]]
#The [[S-layer]] is directly attached to the outer membrane, rather than the peptidoglycan
#If present, [[flagella]] have four supporting rings instead of two
#No [[teichoic acid]]s are present
#[[Lipoproteins]] are attached to the polysaccharide backbone whereas in Gram-positive bacteria no lipoproteins are present
 
==Example species==
The [[proteobacteria]] are a major group of Gram-negative bacteria, including ''[[Escherichia coli]]'', ''[[Salmonella]]'', and other [[Enterobacteriaceae]], ''[[Pseudomonas]]'', ''[[Moraxella catarrhalis|Moraxella]]'', ''[[Helicobacter]]'', ''Stenotrophomonas'', ''[[Bdellovibrio]]'', [[acetic acid bacteria]], ''[[Legionella]]'' and many others. Other notable groups of Gram-negative bacteria include the [[cyanobacteria]], [[spirochaete]]s, [[green sulfur bacteria|green sulfur]] and [[green non-sulfur bacteria|green non-sulfur]] bacteria.
 
Medically relevant Gram-negative [[Coccus|cocci]] include three organisms, which cause a [[sexually transmitted disease]] (''[[Neisseria gonorrhoeae]]''), a [[meningitis]] (''[[Neisseria meningitidis]]''), and respiratory symptoms (''[[Moraxella catarrhalis]]'').
 
Medically relevant Gram-negative [[bacilli]] include a multitude of species. Some of them primarily cause respiratory problems (''[[Hemophilus influenzae]]'', ''[[Klebsiella pneumoniae]]'', ''[[Legionella pneumophila]]'', ''[[Pseudomonas aeruginosa]]''), primarily urinary problems (''[[Escherichia coli]]'', ''[[Proteus mirabilis]]'', ''[[Enterobacter]] cloacae'', ''[[Serratia marcescens]]''), and primarily gastrointestinal problems (''[[Helicobacter pylori]]'', ''[[Salmonella enteritidis]]'', ''[[Salmonella typhi]]'').
 
Nosocomial gram negative bacteria include Acinetobacter baumanii, which cause bacteremia, secondary meningitis, and ventilator-associated pneumonia in intensive care units of hospital establishments.
 
==Medical treatment==
One of the several unique characteristics of Gram-negative bacteria is the [[outer membrane]]. This outer membrane is responsible for protecting the bacteria from several [[antibiotic]]s, dyes, and [[detergent]]s which would normally damage the inner membrane or cell wall ([[peptidoglycan]]). The outer membrane provides these bacteria with resistance to [[lysozyme]] and [[penicillin]]. Fortunately, alternative medicinal treatments such as lysozyme with [[EDTA]], and the antibiotic [[ampicillin]] have been developed to combat the protective outer membrane of some pathogenic Gram-negative organisms.
 
==See also==
* [[Gram-positive]]
 
== References ==
* {{cite book | last = Baron | first = Samuel | title = Medical Microbiology | edition = 4th ed. | publisher = The University of Texas Medical Branch at Galveston | year = 1996 | id = ISBN 0-9631172-1-1 | url = http://www.ncbi.nlm.nih.gov/books/bv.fcgi?call=bv.View..ShowTOC&rid=mmed.TOC&depth=10 }}
* {{cite book | author = Madigan, Michael; Martinko, John (editors) | title = Brock Biology of Microorganisms | edition = 11th ed. | publisher = Prentice Hall | year = 2005 | id = ISBN 0-13-144329-1 }}
* {{NCBI-scienceprimer}}
 
==External links==
*[http://opm.phar.umich.edu/localization.php?localization=Bacterial%20gram-negative%20inner%20membrane 3D structures of proteins from inner membranes of Gram-negative bacteria]
*[http://opm.phar.umich.edu/localization.php?localization=Bacterial%20gram-negative%20outer%20membrane 3D structures of proteins from outer membranes of Gram-negative bacteria]
 
[[Thể loại:Vi trùng học]]
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