Thermo Scientific™ Oxoid™ Lysine Iron Agar (Dehydrated)

The Oxoid™ Lysine Iron Agar (LIA) is a differential diagnostic medium specifically formulated for detecting Salmonella spp., including Salmonella arizonae. This medium enables the identification of bacteria through lysine decarboxylase activity and hydrogen sulfide (H₂S) production, making it a vital tool for clinical, food safety, and research applications.

Key Features

1. Differential Medium:
   • Detects lysine decarboxylation, H₂S production, and other metabolic activities specific to Salmonella.
   • Differentiates Salmonella spp. from other Enterobacteriaceae.
2. Sensitive to Lactose-Fermenting Salmonellae:
   • Allows detection of lactose-fermenting Salmonella arizonae, often missed by traditional media.
3. Precise Identification:
   • Differentiates between Salmonella, Proteus, Citrobacter, and other enteric bacteria based on metabolic reactions.
4. Versatile Usage:
   • Applicable in clinical microbiology for pathogen detection.
   • Supports foodborne pathogen investigations.
5. Ready-to-Prepare Formula:
   • Dehydrated medium supplied for convenient preparation and storage.

Typical Formula (per litre)

Preparation Instructions

1. Suspend 34 g of dehydrated medium in 1 litre of distilled water.
2. Heat to boiling to dissolve completely.
3. Dispense into tubes.
4. Sterilize by autoclaving at 121°C for 15 minutes.
5. Cool tubes in an inclined position to form slants with deep butts.

Interpretation of Results

Note:

• Salmonella paratyphi A does not produce lysine decarboxylase, resulting in an alkaline slant and acid butt.
• Proteus species producing H₂S do not blacken this medium.

Storage Conditions

• Dehydrated Medium: Store at 10–30°C.
• Prepared Medium: Store at 2–8°C.
• Use before the expiry date indicated on the label.

Quality Control

Applications

1. Clinical Diagnostics:
   • Identification of Salmonella infections, including lactose-fermenting Salmonella arizonae.
2. Food Safety Testing:
   • Detection of foodborne Salmonella spp. to ensure compliance with safety standards.
3. Research:
   • Studies on bacterial metabolism, particularly lysine decarboxylation and H₂S production.

Advantages

1. Sensitive and Specific:
   • Detects lactose and non-lactose fermenting Salmonella with high accuracy.
2. Comprehensive Results:
   • Differentiates multiple Enterobacteriaceae species in a single test.
3. Ease of Preparation:
   • Simple preparation and storage make it convenient for routine use.

The Oxoid™ Lysine Iron Agar (CM0381) is a reliable diagnostic medium designed for rapid detection and differentiation of Salmonella spp. and other Enterobacteriaceae based on metabolic characteristics. Its high sensitivity and specificity make it a valuable tool in clinical, food safety, and research laboratories.

References

1. Edwards, P.R., and Fife, M.A. (1961). Appl. Microbiol. 9:478-480.
2. Moeller, V. (1954). Acta Pathol. Microbiol. Scand. 355:259-277.
3. Ewing, W.H., Davis, B.R., and Edwards, P.R. (1960). Pub. Hlth Labs. 18:77-83.
4. Thatcher, F.S., and Clark, D.S. (1968). University of Toronto Press, p.100.
5. Timms, L. (1971). Med. Lab. Technol. 28:150-156.
6. Finegold, S.M., and Martin, W.J. (1982). Bailey & Scott’s Diagnostic Microbiology, 6th Ed., C.V. Mosby.