Canadian Society for Medical Laboratory Science (CSMLS) Practice Exam

What is the purpose of activated charcoal present in transport media?

1. Indicate a contaminated specimen

2. Prevent overgrowth of extraneous organisms

3. Maintain anaerobic conditions

4. Absorb toxic substances

The correct answer is: Absorb toxic substances

Activated charcoal serves a critical purpose in transport media by absorbing toxic substances that may hinder the viability of microorganisms during transport. This function is vital because it ensures that the microbial specimens remain viable and can be accurately analyzed upon arrival in the laboratory. Toxic substances can potentially interfere with the growth and recovery of organisms, so the presence of activated charcoal helps to create a more favorable environment for the target organisms. Maintaining the integrity of specimens during transport is crucial for accurate testing and diagnosis. Although other components in transport media may assist in suppressing unwanted organisms or preserving certain conditions, the primary role of activated charcoal is indeed to minimize the harmful effects of toxins. This enhances the reliability of microbiological tests performed on the specimens once they reach the lab.