Nonpyogenic streptococci

Definition

Nonpyogenic streptococci are a group of Gram-positive bacteria that do not produce pus. They are part of the normal flora but can occasionally cause infections.

5 Must Know Facts For Your Next Test

1. Nonpyogenic streptococci are different from pyogenic streptococci, which cause pus formation.
2. These bacteria are typically catalase-negative and grow in chains or pairs.
3. They include species such as Streptococcus mitis and Streptococcus salivarius.
4. Nonpyogenic streptococci are commonly found in the oral cavity and upper respiratory tract.
5. They can be involved in dental caries, endocarditis, and other non-purulent infections.

Review Questions

• What distinguishes nonpyogenic streptococci from pyogenic streptococci?
• Where are nonpyogenic streptococci commonly found in the human body?
• Name two species of nonpyogenic streptococci.

Related terms

Gram-Positive Bacteria: Bacteria that have a thick peptidoglycan layer in their cell walls and retain the crystal violet stain used in Gram staining.

Catalase-Negative: Characteristic of bacteria that do not produce the enzyme catalase, which breaks down hydrogen peroxide.

Endocarditis:

An infection of the inner lining of the heart chambers and valves, often caused by bacteria such as nonpyogenic streptococci.