What is the most common cause of anorectal abscesses?

Anorectal abscesses are typically caused by a bacterial infection, and the most common pathogens involved are Escherichia coli and Staphylococcus aureus. These bacteria are part of the normal flora of the gastrointestinal tract and skin, respectively. When there is an obstruction of the anal glands, it can lead to infection and subsequent abscess formation.

E. coli, which can thrive in the anaerobic environment of the rectum, is frequently involved in causing these infections due to its abundance and virulence. Staphylococcus aureus can also play a significant role in skin infections and can exacerbate the condition by contributing to abscess formation. Together, these organisms represent the most common bacterial culprits in anorectal abscesses, which aligns with the provided answer.