What should the nurse do first when an elderly client on antibiotics reports frequent watery stools?

When an elderly client on antibiotics reports frequent watery stools, the first step should be to place the client on contact precautions. This is crucial because frequent watery stools can indicate a potential infection, such as Clostridium difficile (C. difficile) colitis, which is associated with antibiotic use and can easily spread to other patients if not contained.

Implementing contact precautions helps to minimize the risk of transmitting the infection to others by ensuring that the client is isolated from those who are susceptible and that the healthcare staff uses personal protective equipment (PPE) when interacting with the client. This proactive approach is vital in preventing an outbreak in a healthcare setting.

The other options, while important, are subsequent steps that can be taken after ensuring that the client is appropriately protected to prevent the spread of infection. Educating the client on handwashing, obtaining stool specimens for culture, or notifying the primary healthcare provider about the loose stools are important, but these actions should follow the initial implementation of contact precautions to prioritize infection control.