Final answer:
After cleaning and redressing the wound, the nurse should send a sample of the infection to a medical lab for analysis.
Step-by-step explanation:
When a nurse discovers that a patient's wound infection has gotten worse, the next step after cleaning and redressing the wound would be to send a sample of the infection to a medical lab for analysis. By looking at the bacteria under a microscope, healthcare professionals can identify the specific cause of the infection. This is important because different bacteria may require different medications to effectively treat the infection. In some cases, the infection may continue to worsen despite antibiotic treatment, and further interventions like surgical removal of infected tissue may be necessary.