Triple sugar iron agar: Difference between revisions

Revision as of 12:27, 24 August 2020

Contains three sugars (lactose, sucrose, and glucose) as well as iron, within a solid agar medium
- Peptone as a source of nitrogen
- Medium is originally reddish due to the phenol red indicator, which turns yellow in acidic conditions
- Tubes contain a well-oxygenated slant and a poorly-oxygenated butt which need to be interpreted separately
- Inoculated with a stab down towards the butt followed by streaking the slant
After 18 to 24 hours at 35°C with a loose cap, the final colour depends on the metabolism of the four components
- Glucose alone fermented: butt turns yellow (acid), slant stays red (alkaline) (Alk/A)
- Lactose or sucrose fermented: both butt and slant turn yellow (acid) (A/A)
- No fermentation of glucose, lactose, or sucrose: both butt and slant stay red (Alk/Alk)
- Iron: if hydrogen sulfide (H₂S) is produced, the iron will turn black
- Gas may be formed with active fermentation of either glucose or lactose/sucrose

Interpretation

Slant	Butt	Gas	H2S	Fermentation	Examples
Red	Red	No	No	—	Pseudomonas
Red	Yellow	No	No	G	Shigella, Serratia
Yellow	Yellow	Yes	No	G/L/S	Escherichia, Klebsiella, Enterobacter
Yellow	Yellow	Yes	Yes	G/L/S
Red	Yellow	Yes	Yes	G	Salmonella, Proteus

@@ Line 1: / Line 1: @@
-* Contains three sugars (lactose, sucrose, and glucose) as well as iron, within a solid agar medium
+*Contains three sugars (lactose, sucrose, and glucose) as well as iron, within a solid agar medium
-** Peptone as a source of nitrogen
+**Peptone as a source of nitrogen
-** Medium is originally reddish due to the phenol red indicator, which turns yellow in acidic conditions
+**Medium is originally reddish due to the phenol red indicator, which turns yellow in acidic conditions
-** Tubes contain a well-oxygenated '''slant''' and a poorly-oxygenated '''butt''' which need to be interpreted separately
+**Tubes contain a well-oxygenated '''slant''' and a poorly-oxygenated '''butt''' which need to be interpreted separately
-** Inoculated with a stab down towards the butt followed by streaking the slant
+**Inoculated with a stab down towards the butt followed by streaking the slant
-* After 18 to 24 hours at 35°C with a loose cap, the final colour depends on the metabolism of the four components
+*After 18 to 24 hours at 35°C with a loose cap, the final colour depends on the metabolism of the four components
-** Glucose alone fermented: butt turns yellow, slant stays red
+**Glucose alone fermented: butt turns yellow (acid), slant stays red (alkaline) (Alk/A)
-** Lactose or sucrose fermented: both butt and slant turn yellow
+**Lactose or sucrose fermented: both butt and slant turn yellow (acid) (A/A)
+**No fermentation of glucose, lactose, or sucrose: both butt and slant stay red (Alk/Alk)
-** Iron: if hydrogen sulfide (H<sub>2</sub>S) is produced, the iron will turn black
+**Iron: if hydrogen sulfide (H<sub>2</sub>S) is produced, the iron will turn black
-** Gas may be formed with active fermentation of either glucose or lactose/sucrose
+**Gas may be formed with active fermentation of either glucose or lactose/sucrose
-== Interpretation ==
+==Interpretation==
 {| class="wikitable"
-! Slant  !! Butt   !! Gas !! H2S !! Fermentation !! Examples
+!Slant!!Butt!!Gas!!H2S!!Fermentation!!Examples
 |-
-| Red    || Red    || No  || No  || —            || ''Pseudomonas''
+|Red||Red||No||No||—||''Pseudomonas''
 |-
-| Red    || Yellow || No  || No  || G            || ''Shigella'', ''Serratia''
+|Red||Yellow||No||No||G||''Shigella'', ''Serratia''
 |-
-| Yellow || Yellow || Yes || No  || G/L/S
+|Yellow||Yellow||Yes||No||G/L/S
-| [[Escherichia species|''Escherichia'']], [[Klebsiella species|''Klebsiella'']], [[Enterobacter species|''Enterobacter'']]
+|[[Escherichia species|''Escherichia'']], [[Klebsiella species|''Klebsiella'']], [[Enterobacter species|''Enterobacter'']]
 |-
-| Yellow || Yellow || Yes || Yes || G/L/S        ||
+|Yellow||Yellow||Yes||Yes||G/L/S||
 |-
-| Red    || Yellow || Yes || Yes || G            || ''Salmonella'', ''Proteus''
+|Red||Yellow||Yes||Yes||G||''Salmonella'', ''Proteus''
 |}
-== Further Reading ==
+==Further Reading==
-* Microbe Online. [https://microbeonline.com/triple-sugar-iron-agar-tsi-principle-procedure-and-interpretation/ Triple Sugar Iron Agar (TSI): Principle, Procedure and Interpretation]
+*Microbe Online. [https://microbeonline.com/triple-sugar-iron-agar-tsi-principle-procedure-and-interpretation/ Triple Sugar Iron Agar (TSI): Principle, Procedure and Interpretation]
 [[Category:Diagnostics]]