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

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Phiên bản lúc 19:23, ngày 18 tháng 2 năm 2007

Gram âm là tên tập hợp các loại vi khuẩn không giữ được tinh thể tím khi cho phản ứng với hoá chất thử nghiệm theo tiêu chuẩn nhuộm Gram. Tiêu chuẩn này được dùng để phân dạng vi khuẩn làm hai loại Gram âm và Gram dương - dựa theo khác biệt của vỏ tế bào.

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.

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@@ Dòng 3: / Dòng 3: @@
 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 dịch}}
+{{Sơ khai}}
-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]]