Triple Sugar Iron (TSI) Agar
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Triple Sugar Iron (TSI) Agar is a differential medium used to identify enteric bacteria based on their ability to ferment glucose, lactose, and sucrose, along with the production of hydrogen sulfide
- Lower cost without compromising quality.
- Clearly distinguish between glucose, lactose, and sucrose fermenters.
- Easily detect hydrogen sulfide production.
- Accurate differentiation of Enterobacteriaceae.
- Aids in preliminary identification of Salmonella, Shigella, and other enteric pathogens
Problem
Inconsistent results waste time and resources
Wasted media and reagents. When unreliable media gives inconclusive results, you've wasted not just the agar but all the time and materials preparing and inoculating it.
Delayed identification. Poor quality media means retesting and delays in critical identification processes.
Extra confirmation steps. When your initial screening is unreliable, you need additional tests to confirm results.
Solution
Reliable differentiation you can count on
Consistent formulation. Each batch provides clear, distinct reactions that leave no room for interpretation doubts.
Clear color changes. Distinct yellow (acid) and red (alkaline) reactions make interpretation straightforward.
Reduced follow-up testing. Accurate preliminary results mean fewer confirmatory tests needed.
Problem
Budget constraints limit testing capabilities
High costs of premium media. Quality differential media often comes with premium pricing.
Limited testing volume. Budget restrictions may force you to reduce testing frequency.
Expensive alternatives. Other identification methods often require costly equipment or reagents.
Solution
More completed tests for the same cost
Lower cost without compromise. Get the same quality less than leading competitors.
More tests per dollar. Your budget stretches further, allowing for more comprehensive testing programs.
Cost-effective screening. Simple, reliable screening before investing in expensive confirmatory tests.
Where is our TSI agar being used right now?
Clinical Diagnostic Laboratories
In clinical settings, rapid and accurate identification of enteric pathogens is essential for proper patient care. TSI Agar provides a cost-effective first step in the differentiation of clinically significant bacteria.
- Preliminary identification of Salmonella and Shigella from clinical specimens.
- Differentiation of lactose-fermenting coliforms from non-lactose fermenters.
- Screening stool samples for potential pathogens.
- Part of workup for gastrointestinal infection diagnosis.
- Supporting antimicrobial susceptibility workflow with accurate organism identification.
- Identification of opportunistic pathogens in immunocompromised patients.
- Differentiation of Enterobacteriaceae in urinary tract infections.
- Screening for enteric pathogens in outbreak investigations.
Food Safety Testing Laboratories
Food safety depends on reliable pathogen detection. TSI Agar helps food testing labs identify potential contaminants efficiently.
- Screening food samples for Salmonella contamination.
- Processing raw ingredient samples for pathogen testing.
- Analyzing finished product samples for quality assurance.
- Supporting HACCP verification testing.
- Investigating food poisoning incidents.
- Quality control testing in food production facilities.
- Differentiating harmless bacteria from potential pathogens in food products.
Water Quality Testing
Municipal and environmental testing facilities rely on accurate microbial identification to ensure safe water supplies. TSI Agar supports these critical testing programs.
- Differentiation of bacteria isolated from water samples.
- Preliminary identification of potential waterborne pathogens.
- Supporting compliance testing for water quality standards.
- Environmental monitoring of water treatment facilities.
- Testing recreational water for public safety.
- Analyzing wastewater for microbial content.
Academic and Research Laboratories
Teaching labs and research facilities need reliable, cost-effective media for student training and experimental work. TSI Agar provides consistent performance at a budget-friendly price.
- Student laboratory exercises for microbial identification.
- Teaching differential media reactions and interpretation.
- Research on bacterial metabolism and fermentation patterns.
- Cost-effective screening of environmental isolates.
- Undergraduate microbiology course demonstrations.
- Classifying unknown bacterial isolates in study collections.
Pharmaceutical Quality Control
Pharmaceutical testing demands the highest standards of quality and reliability. TSI Agar supports critical QC testing protocols while helping manage costs.
- Microbial identification in cleanroom monitoring programs.
- Screening for objectionable organisms in product testing.
- Supporting USP microbial enumeration tests.
- Environmental monitoring of production facilities.
- Raw material quality testing.
- Process validation studies.
- Investigation of microbial contamination events.
TSI Agar Specifications
| Feature | Details |
|---|---|
| Indicators | Phenol red (pH), ferrous sulfate (H₂S) |
| Appearance | Red/orange medium that slants well |
| Typical reactions | Varied by organism (see interpretation guide) |
| Quality control strains |
|
| Storage requirements | 2-8°C, protected from light |
| Shelf life | Refer to expiration date on package |
| Packaging options | Slants, tubes, and dehydrated powder formats available |
TSI Agar compared to alternative identification methods
When identifying enteric bacteria, laboratories have several options. Understanding when to use TSI Agar versus other methods helps optimize your workflow and budget.
Traditional Biochemical Tests
| Method | Comparison to TSI Agar |
|---|---|
| Kligler Iron Agar (KIA) | Similar to TSI but lacks sucrose, potentially missing some fermentation patterns. TSI provides more comprehensive differentiation by detecting sucrose fermenters that don't utilize lactose. |
| Individual biochemical tests (indole, citrate, urease, etc.) | While more specific, running separate tests is more expensive and time-consuming than the multiple parameters obtained from a single TSI tube. TSI serves as an excellent screening tool to guide which additional tests are needed. |
| SIM Medium | Tests for sulfide, indole, and motility but lacks carbohydrate fermentation detection. Often used alongside TSI rather than as a replacement. |
Automated and Commercial Systems
| Method | Comparison to TSI Agar |
|---|---|
| API 20E and similar strips | Provides more comprehensive identification but at significantly higher cost (typically $5-15 per test vs. less than $1 for TSI). TSI is still valuable for initial screening before committing to these more expensive methods. |
| VITEK and other automated systems | Offers faster, more definitive identification but requires substantial equipment investment. Many labs use TSI for routine work and reserve automated systems for critical or difficult isolates |
Molecular and Advanced Methods
| Method | Comparison to TSI Agar |
|---|---|
| MALDI-TOF Mass Spectrometry | Provides rapid, accurate identification but requires expensive equipment ($100,000+). TSI remains practical for labs without access to this technology. |
| PCR and gene sequencing | Offers definitive genetic identification but costs significantly more and often requires specialized expertise. TSI continues to be valuable for routine screening and in resource-limited settings. |
When to use TSI Agar vs. alternatives
Choose TSI Agar when…
- Performing initial screening of enteric isolates.
- Working with budget constraints.
- In educational settings teaching classic microbiological techniques.
- Quick presumptive identification is sufficient.
- In facilities without access to advanced equipment.
Consider alternatives when…
- Definitive species-level identification is required.
- Dealing with unusual or clinically critical isolates.
- High-throughput testing justifies automation.
- Regulatory compliance requires specific methodologies.
Even labs equipped with advanced identification systems often maintain TSI Agar in their workflow as a cost-effective screening step before progressing to more expensive confirmatory methods.
Frequently asked questions about TSI Agar
Q: How do I interpret TSI Agar results?
A: TSI Agar results are interpreted based on color changes in the slant and butt, along with the presence of gas or hydrogen sulfide:
- Alkaline/Acid (K/A): Red slant, yellow butt - Only glucose fermentation.
- Acid/Acid (A/A): Yellow slant, yellow butt - Glucose and lactose/sucrose fermentation.
- Alkaline/Alkaline (K/K): Red slant, red butt - No fermentation of sugars.
- H₂S production: Black precipitate in the medium.
- Gas production: Bubbles or cracks in the medium.
Q: What organisms can be identified using TSI Agar?
A: TSI Agar is particularly useful for differentiating members of Enterobacteriaceae, including:
- Salmonella species (typically K/A with H₂S).
- Shigella species (typically K/A without H₂S).
- E. coli (typically A/A with gas).
- Proteus species (typically K/A with H₂S).
- Citrobacter species (typically A/A or K/A with variable H₂S).
- Klebsiella species (typically A/A with gas).
Q: What's the difference between TSI Agar and Kligler Iron Agar (KIA)?
A: TSI Agar contains three sugars (glucose, lactose, and sucrose), while KIA contains only two (glucose and lactose). The addition of sucrose in TSI Agar allows for the detection of sucrose-fermenting organisms that don't ferment lactose, providing additional differentiation capabilities.
Q: Is TSI Agar used alone for bacterial identification?
A: While TSI Agar provides valuable information for preliminary identification, complete identification typically requires additional biochemical tests or other diagnostic methods. TSI Agar serves as an excellent screening medium to guide further testing.
Q: How should I inoculate TSI Agar for best results?
A: TSI Agar should be inoculated by stabbing the butt and streaking the slant. Using a straight inoculating needle, stab to the bottom of the tube, then withdraw along the same path and streak the slant surface in a zigzag pattern. Loosely cap the tube to allow for aerobic conditions.
Q: How long should I incubate TSI Agar tubes?
A: TSI Agar tubes are typically incubated at 35-37°C for 18-24 hours. Some weak H₂S producers may require up to 48 hours to show characteristic black precipitate.
Q: Do you offer bulk discounts for TSI Agar?
A: Yes, volume discounts are available for larger orders. Contact our Customer Service Department at 800-328-8378 for specific pricing on bulk orders.
Q: Can TSI Agar be used for environmental samples?
A: Yes, TSI Agar can be used for testing environmental isolates, particularly when screening for enteric bacteria in water, soil, or other environmental samples. However, environmental isolates may sometimes give atypical reactions.
Q: What quality control procedures should I follow with TSI Agar?
A: Quality control should include testing known positive and negative control organisms with each new lot. Recommended control strains include E. coli (ATCC 25922), S. typhimurium (ATCC 14028), and P. aeruginosa (ATCC 27853).
Q: How should TSI Agar be stored?
A: Store prepared tubes at 2-8°C, protected from light. Avoid freezing and excessive heat. Allow refrigerated tubes to warm to room temperature before inoculation.
70+ years of expertise
We've been supplying labs, food businesses, and research organizations since 1959.
Our team understands the importance of reliable media for your critical testing.
Decades of experience means we've seen and solved most challenges related to microbiological testing.
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Choose your TSI Agar format and quantity below
| Item No. | Brand Name | Size | Unit of Measure | Your Cost | Purchase |
|---|---|---|---|---|---|
|
TSI AGAR; 500G
T20-107
|
Alpha Biosciences | 500g | Each |
$53.54
|