Final answer:
Individuals with compromised immune systems are at the greatest risk for developing an intracellular pathogen infection.
Step-by-step explanation:
The client who is at the greatest risk for developing an intracellular pathogen infection is a person with a compromised immune system. When the immune system is weakened, it is less able to fight off infections, including those caused by intracellular pathogens. Examples of individuals with compromised immune systems include people with HIV/AIDS, cancer patients undergoing chemotherapy, and organ transplant recipients who are on immunosuppressive medications.