What type of bacteria can be responsible for causing skin infections?

Each type of bacteria mentioned in the options has the potential to cause skin infections, which makes 'All of the above' the correct answer.

Spirilla are spiral-shaped bacteria that can lead to various infections, including some skin conditions. Streptococci are known for causing a variety of infections, such as strep throat but can also affect the skin, leading to conditions like impetigo. Bacilli, which are rod-shaped bacteria, are also responsible for various infections, including skin infections.

Since all three types of bacteria can indeed cause skin infections, the comprehensive nature of the correct answer reflects the understanding that different bacterial shapes and categories contribute to potential health issues.