Although bacterial growth and invasiveness can challenge the body's defenses and impair normal function, often the symptoms of a bacterial infection are due to the production of specific exotoxins. An exotoxin is a protein molecule (with one or more subunits) that is secreted by bacteria at the site of infection. The secreted toxin may act locally or systemically via the bloodstream. Exotoxins generally fall into several types:
| Pathogen | Exotoxin | Effect |
| Bacillus anthracis | Edema factor | ↑ cAMP = edema |
| Lethal factor | Kills cell | |
| Bordetella pertussis | Pertussis toxin (PTx) | Inactivates G-protein = ↑ cAMP |
| Clostridium botulinum | Botulinum toxin (botox) | ↓ Acetylcholine release = flaccid paralysis |
| Clostridium tetani | Tetanus toxin | ↓ Inhibitory neurotransmitter release = spastic paralysis |
| Corynebacterium diphtheriae | Diphtheria toxin | Binds EF-2, ↓ protein synthesis = cell death |
| ETEC | Heat -labile enterotoxin (LT-I) | same as CTx |
| Heat-stable enterotoxin (STa) | increases cGMP = fluid hypersecretion | |
| EHEC | Shiga toxins (STx-1 and STx-2) | ↓ protein synthesis = ↓ fluid absorption; cell death; glomerular damage = HUS |
| Pseudomonas aeruginosa | Exotoxin A | Same as DTx |
| Shigella dysenteriae | Shiga toxin (STx) | ↓ protein synthesis = ↓ fluid absorption; cell death |
| Shigella spp. | Shiga-like toxin | similar to ST |
| Staphylococcous aureus | Toxic shock syndrome toxin (TSST) | superantigen |
| Staphylococcal enterotoxin | superantigen | |
| Streptococcus pyogenes | Streptococcal pyrogenic exotoxin (Spe) | superantigen |
| Vibrio cholerae | Cholera toxin (CTx) | ↑ cAMP = ↑ fluid secretion & diarrhea |