CHROMagar™ C. perfringens

CHROMagar™ C. perfringens is a specialized chromogenic culture medium designed for the selective isolation, differentiation, and enumeration of Clostridium perfringens in clinical, food, and environmental samples. This medium uses proprietary chromogenic substrates to allow for the rapid and reliable identification of C. perfringens colonies based on specific enzyme activity, which results in distinct colony coloration.

Key Features

1. Selective Isolation:
   • Incorporates selective agents to suppress non-Clostridium perfringens flora while supporting the growth of C. perfringens.
   • Reduces false positives by effectively inhibiting competing microorganisms.
2. Chromogenic Differentiation:
   • Proprietary chromogenic substrates detect specific enzymatic activity in C. perfringens, leading to the development of distinct colony colors.
   • Enables easy differentiation of C. perfringens from other anaerobes or contaminants.
3. Fast and Accurate:
   • Offers results in as little as 24 hours under optimal conditions.
   • Reliable for high-throughput laboratories and routine testing.
4. Versatile Applications:
   • Suitable for a wide range of sample types, including clinical specimens, food products, water, and environmental materials.

Composition

• Selective Agents: Inhibit competing bacteria while allowing the growth of C. perfringens.
• Chromogenic Substrates: Target specific enzymatic reactions unique to C. perfringens.
• Nutrient-Rich Base: Provides essential nutrients for the growth of C. perfringens under anaerobic conditions.
• Agar: Solidifying agent for creating stable culture plates.

Applications and Use Cases

1. Clinical Microbiology

• Purpose: Isolation and identification of Clostridium perfringens from clinical specimens such as feces or wound exudates.
• Use Case:
  • Detect C. perfringens in cases of gas gangrene or necrotizing enteritis.
  • Rapidly differentiate C. perfringens from other Clostridium species or gut flora in suspected cases of antibiotic-associated diarrhea or food poisoning.
• Advantage:
  • Reduces diagnostic turnaround time compared to traditional methods.
  • Enables precise identification with minimal additional confirmatory tests.

2. Food and Beverage Testing

• Purpose: Monitoring food and beverages for contamination by C. perfringens.
• Use Case:
  • Identify and enumerate C. perfringens in processed meats, dairy products, and other ready-to-eat foods as part of routine safety checks.
  • Assess the microbial quality of food in accordance with regulatory standards.
• Advantage:
  • Provides quantitative results, aiding in compliance with food safety regulations such as ISO 7937 or FDA BAM.

3. Environmental Monitoring

• Purpose: Detection of C. perfringens in water, soil, and waste samples.
• Use Case:
  • Analyze drinking water for C. perfringens spores, which may indicate fecal contamination.
  • Monitor effluent water from sewage treatment plants to assess pathogen removal efficiency.
• Advantage:
  • Chromogenic differentiation simplifies downstream confirmation and reduces labor costs.

4. Veterinary Diagnostics

• Purpose: Detect and quantify C. perfringens in animal feed and clinical specimens from livestock or poultry.
• Use Case:
  • Diagnose necrotic enteritis or enterotoxemia in livestock caused by C. perfringens.
  • Ensure the microbial safety of feed and water provided to animals.
• Advantage:
  • Facilitates early diagnosis, reducing economic losses in animal husbandry.

Protocol

1. Sample Preparation:
   • Homogenize the sample (e.g., food, clinical specimen) in a suitable diluent such as sterile saline or Maximum Recovery Diluent (MRD).
2. Inoculation:
   • Spread 0.1 mL of the prepared sample or serial dilution onto the CHROMagar™ C. perfringens plate.
   • Ensure even distribution to achieve well-isolated colonies.
3. Incubation:
   • Incubate plates at 37°C for 24–48 hours under strict anaerobic conditions (e.g., anaerobic jar with gas-generating sachets).
4. Observation:
   • Examine plates for characteristic colony colors indicative of C. perfringens.
   • Compare results with controls if necessary.
5. Confirmation:
   • Optional confirmatory tests, such as biochemical assays or PCR, can be performed for regulatory or clinical confirmation.

Interpretation of Results

• Characteristic Colonies:
  • C. perfringens: Develops distinct colony coloration (e.g., purple or black) based on chromogenic substrate activity.
  • Other flora: Generally show inhibited growth or non-characteristic colony colors.
• Quantification:
  • Report the count as colony-forming units per gram (CFU/g) or per milliliter (CFU/mL), accounting for dilution factors.

Advantages

• Time-Efficient:
  • Reduces the need for time-intensive confirmatory tests.
• Cost-Effective:
  • Chromogenic differentiation minimizes the requirement for additional reagents or equipment.
• High Specificity:
  • Targets unique enzymatic activity, minimizing false positives.
• User-Friendly:
  • Distinct colony colors make results easy to interpret even for less experienced personnel.

Storage and Stability

• Store the dehydrated medium at 10–30°C in its original packaging.
• Prepared plates should be stored at 2–8°C and used within the recommended shelf life.

Quality Control

• Positive Control: Clostridium perfringens ATCC® 13124 (Good growth, characteristic colony color).
• Negative Control: Non-C. perfringens organisms (e.g., E. coli) should show inhibited growth.

CHROMagar™ C. perfringens provides a robust and reliable solution for the rapid detection, isolation, and quantification of Clostridium perfringens. Its chromogenic differentiation, selectivity, and ease of use make it indispensable for clinical, food, environmental, and veterinary applications.

Colonies Appearance

Clostridium perfringens

orange

C. difficile 

green-blue to green