Answer:
S. typhi shares a parasitic relationship with humans
Lactobacillus shares a mutual relationship with humans
Step-by-step explanation:
S typhi causes infections, which is negative. It feeds off the body but produces no benefit, it harms. Therefore it is a parasite.
Lacto bacteria feed off of food, which benefits itself, but on the other hand aides in digestion and does not harm the human. Both sides are benefited. So the relationship is mutual. No harm done, both prosper.