Final answer:
A genus of bacteria such as Streptococcus is pyogenic because it is a pus-forming bacteria, a characteristic seen in species like S. pyogenes.
Step-by-step explanation:
When a genus of bacteria, such as Streptococcus, is described as pyogenic, it implies that it is a pus forming bacteria. This characteristic is seen in species such as S. pyogenes, which is part of the group A β-hemolytic Streptococcus and is known for causing infections that result in pus production. These bacteria are responsible for various infections ranging from mild to life-threatening, such as bacterial pharyngitis (strep throat), impetigo, and necrotizing fasciitis (flesh-eating disease).
S. pyogenes employs various mechanisms to thrive in the host, including producing a variety of enzymes and toxins that contribute to their pathogenicity and provoke an immune response. As bacteria form pus through these mechanisms, the option that correctly defines pyogenic is that it is a pus-forming bacteria.