Questions: Patients with indwelling catheters (long-term tubes inserted into body orifices for drainage, such as through the urethra and into the urinary bladder) are susceptible to infections because injected solutions are contaminated. bacteria cause infections. infections can be transmitted from other people. biofilms develop on catheters. their immune systems are weakened.

The answer is the fourth one: biofilms develop on catheters.

Explanation for each option:

1. Injected solutions are contaminated: This is not the primary reason for infections in patients with indwelling catheters. While contamination of solutions can cause infections, it is not specific to the use of catheters.

2. Bacteria cause infections: While it is true that bacteria cause infections, this statement is too general and does not specifically address why patients with indwelling catheters are more susceptible.

3. Infections can be transmitted from other people: This is a possible route of infection, but it is not the primary reason for the increased susceptibility in patients with indwelling catheters.

4. Biofilms develop on catheters: This is the correct answer. Biofilms are communities of bacteria that adhere to surfaces, such as catheters, and are encased in a protective matrix. These biofilms are difficult to eradicate and can lead to persistent infections.

5. Their immune systems are weakened: While some patients with indwelling catheters may have weakened immune systems, this is not the primary reason for the increased risk of infection associated with catheter use.

Summary: Patients with indwelling catheters are particularly susceptible to infections because biofilms develop on the catheters. These biofilms provide a protective environment for bacteria, making infections more likely and harder to treat.