Lysine iron agar
Lysine Iron Agar (LIA) is a type of agar medium used in microbiology to differentiate Enterobacteriaceae based on their ability to decarboxylate or deaminate lysine and to produce hydrogen sulfide. It is a valuable tool in the identification of Salmonella, Shigella, and other members of the Enterobacteriaceae family.
Composition[edit | edit source]
Lysine Iron Agar consists of lysine, iron sulfate, sodium thiosulfate, agar, sugars, and a pH indicator. The medium is designed to detect two main reactions: the decarboxylation of lysine to produce cadaverine and the production of hydrogen sulfide (H2S).
Principle[edit | edit source]
The principle behind LIA is to test the organism's ability to decarboxylate lysine and to produce hydrogen sulfide. The medium contains lysine as a substrate for decarboxylation, which, if utilized by the organism, will raise the pH and change the color of the medium due to the pH indicator. The production of hydrogen sulfide, on the other hand, is indicated by the formation of a black precipitate in the medium, resulting from the reaction of H2S with iron sulfate.
Interpretation of Results[edit | edit source]
- Purple Slant/Purple Butt: Indicates lysine decarboxylation, suggesting the organism is capable of utilizing lysine and producing cadaverine, which raises the pH. - Yellow Slant/Yellow Butt: Indicates fermentation of glucose with acid production, lowering the pH. - Black Precipitate: Indicates the production of hydrogen sulfide. - Purple Slant/Yellow Butt: This combination can indicate that the organism is capable of glucose fermentation but not lysine decarboxylation.
Applications[edit | edit source]
Lysine Iron Agar is primarily used in the differentiation of members of the Enterobacteriaceae family, particularly in distinguishing Salmonella and Shigella from other enteric pathogens. It is a standard test in the identification schemes for these bacteria.
Limitations[edit | edit source]
While LIA is a useful diagnostic tool, it is not definitive on its own. Results should be interpreted in conjunction with other biochemical and serological tests for accurate identification of bacterial species.
Lysine iron agar Resources | |
---|---|
|
Search WikiMD
Ad.Tired of being Overweight? Try W8MD's physician weight loss program.
Semaglutide (Ozempic / Wegovy and Tirzepatide (Mounjaro / Zepbound) available.
Advertise on WikiMD
WikiMD's Wellness Encyclopedia |
Let Food Be Thy Medicine Medicine Thy Food - Hippocrates |
Translate this page: - East Asian
中文,
日本,
한국어,
South Asian
हिन्दी,
தமிழ்,
తెలుగు,
Urdu,
ಕನ್ನಡ,
Southeast Asian
Indonesian,
Vietnamese,
Thai,
မြန်မာဘာသာ,
বাংলা
European
español,
Deutsch,
français,
Greek,
português do Brasil,
polski,
română,
русский,
Nederlands,
norsk,
svenska,
suomi,
Italian
Middle Eastern & African
عربى,
Turkish,
Persian,
Hebrew,
Afrikaans,
isiZulu,
Kiswahili,
Other
Bulgarian,
Hungarian,
Czech,
Swedish,
മലയാളം,
मराठी,
ਪੰਜਾਬੀ,
ગુજરાતી,
Portuguese,
Ukrainian
Medical Disclaimer: WikiMD is not a substitute for professional medical advice. The information on WikiMD is provided as an information resource only, may be incorrect, outdated or misleading, and is not to be used or relied on for any diagnostic or treatment purposes. Please consult your health care provider before making any healthcare decisions or for guidance about a specific medical condition. WikiMD expressly disclaims responsibility, and shall have no liability, for any damages, loss, injury, or liability whatsoever suffered as a result of your reliance on the information contained in this site. By visiting this site you agree to the foregoing terms and conditions, which may from time to time be changed or supplemented by WikiMD. If you do not agree to the foregoing terms and conditions, you should not enter or use this site. See full disclaimer.
Credits:Most images are courtesy of Wikimedia commons, and templates Wikipedia, licensed under CC BY SA or similar.
Contributors: Prab R. Tumpati, MD