Final answer:
The nurse should implement standard precautions for a client with urethritis secondary to chlamydial infection, which include hand hygiene and personal protective equipment to prevent transmission.
Step-by-step explanation:
The appropriate precaution for a nurse to implement for a client diagnosed with urethritis secondary to a chlamydial infection is standard precautions. This includes practices like proper hand hygiene, use of personal protective equipment when necessary, and safe injection practices. These precautions are sufficient to prevent the spread of chlamydia, as it is primarily transmitted through sexual contact and not through the air or casual contact. Standard precautions are designed to prevent the transmission of infections that can be acquired by contact with blood, body fluids, non-intact skin, and mucous membranes.