Which organism is commonly associated with dog or cat bites?

Pasteurella multocida is the organism commonly associated with dog or cat bites. This bacterium is a part of the normal flora of the mouths of dogs and cats, and transmission can occur during bites or scratches. Infections caused by Pasteurella multocida are typically characterized by rapid onset of swelling, erythema, and pain at the site of injury, often leading to cellulitis or abscess formation.

In contrast, other organisms listed are not as closely associated with animal bites. For instance, Streptococcus pyogenes is mainly involved in skin infections such as impetigo and cellulitis but is not specifically tied to bites from pets. Escherichia coli is primarily found in the gastrointestinal tract and is more often associated with infections related to fecal contamination rather than bites. Clostridium perfringens is known for causing gas gangrene and food poisoning, but does not have a significant role in infections from dog or cat bites. This specificity makes Pasteurella multocida the most relevant organism in the context of animal bites.