In addition to the integrity of the integumentary system, what other component of the skin protects against bacterial infection?

Oil Glands/Sebaceous glands

Explanation:

Sebaceous glands are microscopic small exocrine oil producing glands in the skin of mammals. These glands are connected to hairs follicles and secrete an oily substance called sebum  on the surface of skin. These glands are present throughout the skin except the palm of hands and sole of feet.

Sebaceous glands are part of skin and help in immune system by providing protection against microorganism such as bacteria. The glands form the acid film on the skin that help in protection against bacteria. The pH of skin is between 4.5-6.2 that protects against alkaline contaminants.

System which regulates and controls growth development and metabolism is Endocrine system. This system completes its tasks through a network of glands, which are small but very important organs that generate, store, and secrete hormones. It secrete hormones directly into the bloodstream internally.
I hope it helped.