Answer the following question given this paragraph: 

A sexually transmitted infection (STI) is a disease that spreads mainly through sexual contact. STIs are more common in teens and young adults than in older people. Bacterial STIs include chlamydia, gonorrhea, and syphilis. Viral STIs include genital warts, genital herpes, and AIDS.


Q: What are chlamydia, gonorrhea, and syphilis an example of?


A:
bacterial stis