Bordet-Gengou Agar vs. Regan-Lowe Charcoal Agar

Attribute	Bordet-Gengou Agar	Regan-Lowe Charcoal Agar
Composition	Potato infusion agar with glycerol, blood, and agar	Buffered charcoal yeast extract agar with antibiotics and charcoal
Use	Isolation of Bordetella pertussis	Isolation of Legionella species
Appearance	Clear, pale yellow agar	Black agar due to charcoal
Incubation	Requires 2-7 days of incubation at 35-37°C	Requires 2-10 days of incubation at 35-37°C

Introduction

Bordet-Gengou Agar and Regan-Lowe Charcoal Agar are two types of agar used in microbiology for the isolation and cultivation of specific bacteria. While both agars serve similar purposes, they have distinct attributes that make them suitable for different types of bacteria and experimental conditions.

Composition

Bordet-Gengou Agar is a selective medium that contains potato infusion, glycerol, agar, and defibrinated sheep blood. The potato infusion provides nutrients for the growth of Bordetella pertussis, the bacteria that this agar is specifically designed to isolate. On the other hand, Regan-Lowe Charcoal Agar contains charcoal, agar, and various antibiotics such as vancomycin and polymyxin B. The charcoal in this agar helps to neutralize toxic substances produced by bacteria, making it ideal for the isolation of Legionella species.

Selectivity

Bordet-Gengou Agar is highly selective for Bordetella pertussis due to the presence of specific nutrients and blood components that promote the growth of this bacterium while inhibiting the growth of other organisms. In contrast, Regan-Lowe Charcoal Agar is selective for Legionella species by incorporating antibiotics that target other bacteria commonly found in environmental samples, allowing for the isolation of Legionella colonies with minimal interference.

Use in Diagnosis

Bordet-Gengou Agar is commonly used in the diagnosis of pertussis, also known as whooping cough. The selective nature of this agar allows for the isolation and identification of Bordetella pertussis from clinical samples, aiding in the accurate diagnosis of the disease. On the other hand, Regan-Lowe Charcoal Agar is used in the diagnosis of Legionnaires' disease, a severe form of pneumonia caused by Legionella bacteria. The selective properties of this agar enable the isolation of Legionella colonies from respiratory samples, facilitating the diagnosis of the infection.

Growth Characteristics

Bordet-Gengou Agar promotes the growth of Bordetella pertussis as small, smooth, and glistening colonies with a characteristic "mercury drop" appearance. These colonies are typically observed after 2-7 days of incubation at 35-37°C in a humidified atmosphere. In comparison, Regan-Lowe Charcoal Agar supports the growth of Legionella species as small, translucent, and dewdrop-like colonies. Legionella colonies appear after 3-10 days of incubation at 35-37°C in a humidified atmosphere, exhibiting a distinct morphology that aids in their identification.

Conclusion

In conclusion, Bordet-Gengou Agar and Regan-Lowe Charcoal Agar are two specialized agars used in microbiology for the isolation and cultivation of specific bacteria. While Bordet-Gengou Agar is selective for Bordetella pertussis and commonly used in the diagnosis of pertussis, Regan-Lowe Charcoal Agar is selective for Legionella species and employed in the diagnosis of Legionnaires' disease. Understanding the unique attributes of these agars is essential for microbiologists to choose the appropriate medium for their research or diagnostic purposes.