Liver Infusion Agar

Product Overview

Liver Infusion Agar (AS-1275) is a rich, non-selective solid medium specifically designed for the primary isolation, subculture, and maintenance of extremely fastidious microorganisms — in particular, strict anaerobes and slow-growing bacterial pathogens that fail to grow or grow poorly on conventional blood agar or standard peptone media. The medium derives its outstanding nutritional value from a concentrated liver tissue infusion, which naturally provides hemin, vitamin K, NAD, essential amino acids, long-chain fatty acids, and biological reducing compounds, generating a micro-environment of inherently low oxidation-reduction potential (Eh) that is hospitable to oxygen-sensitive organisms.

The deliberate exclusion of fermentable carbohydrates prevents inhibitory acid accumulation during extended incubation of up to 14 days. The solidified agar matrix enables colony isolation, morphology assessment, and compatibility with overlay techniques such as the egg-yolk (Nagler) reaction for Clostridium perfringens identification.

Intended Applications

• Primary isolation and subculture of strict anaerobes from clinical specimens (wound swabs, blood cultures, tissue biopsies, pus)
• Cultivation and propagation of Brucella spp. (with or without serum supplementation)
• Cultivation of Francisella tularensis under appropriate BSL-3 containment
• Maintenance of anaerobic stock cultures: Clostridium, Bacteroides, Fusobacterium, Actinomyces spp.
• Base medium for egg-yolk overlay (Nagler plates) for Clostridium perfringens lecithinase detection
• Base for special indicator or selective supplementation for anaerobic identification media
• Cultivation of nutritionally demanding streptococci and other fastidious organisms

Key Features

• Natural liver infusion — hemin, vitamin K, NAD, amino acids, and biological reducing compounds
• Superior to blood agar for many slow-growing and oxygen-injured anaerobes
• Low carbohydrate content — minimal acid production; ideal for extended anaerobic incubation
• Solid agar format — colony isolation, morphology assessment, and overlay compatibility
• Flexible supplementation — compatible with blood, serum, hemin, vitamin K, and selective agents

Product Identification

Composition (per litre prepared medium)

Preparation

Suspend 40.0 g dehydrated medium in 1 litre purified water. Boil with agitation until agar is completely dissolved. Autoclave at 121°C for 15 minutes. Cool to 45–50°C before adding heat-labile supplements (blood, serum, hemin, vitamin K). Pour ~18–20 mL per 90 mm plate. For strict anaerobes, pour in anaerobic cabinet and pre-reduce plates for ≥ 24 h before use. Final pH: 7.2 ± 0.2 at 25°C.

Incubation