I read you can get tetanus from dust and saliva. how is that possible?

Clostridium: The bacteria that causes tetanus is called Clostridium tetani & is found in soil, house dust, animal intestines, and human feces. If you are healthy and vaccinated you will not contract it. The usual mechanism to contract it is to get a tetanus-prone wound, one that is large or particularly deep & contaminated with the bacteria (usually dirt or a bite). Wash the wound + ensure you're vaccinated.

Explanation : To get the tetanus need to have open wound, the first of all, and dirty wound. Dirty dust is part of dirty ground, but house dust is benign.

Clostridium tetani: Inoculation of a wound with dirt containing the organism Clostridium tetani causes tetanus. Get vaccinated for tetanus. If and when you get a wound that get contaminated with dirt, get a booster dose of the vaccine. For good health - Have a diet rich in fresh vegetables, fruits, whole grains, milk and milk products, nuts, beans, legumes, lentils and small amounts of lean meats. Avoid saturated fats. Drink enough water daily, so that your urine is mostly colorless. Exercise at least 150 minutes/week and increase the intensity of exercise gradually. Do not use tobacco, alcohol, weed or street drugs in any form. Practice safe sex, if you have sex.