Final answer:
The non-spore-forming Gram-positive bacilli pathogens predominantly include Erysipelothrix rhusiopathiae and Lactobacillus species, as well as Listeria monocytogenes, whereas Clostridium tetani is spore-forming and not included.
Step-by-step explanation:
The predominant non-spore-forming Gram-positive bacilli pathogens include Erysipelothrix rhusiopathiae, responsible for a disease known as erysipeloid, and Lactobacillus species, usually involved in fermented food production but can be opportunistic pathogens. Listeria monocytogenes is also a non-spore-former and is responsible for listeriosis, which can be serious for pregnant women and immunocompromised individuals.
On the other hand, Clostridium tetani is a spore-forming Gram-positive bacillus known for causing tetanus; hence, it does not align with the question focusing on non-spore formers. These bacteria are responsible for causing diseases such as diphtheria and pneumonia respectively.