The goal of this observational study is to measure how well the antibiotic delafloxacin penetrates into the blood and various body tissues in adult patients over 18 years old. Specifically, this study focuses on patients who are receiving the drug to treat bacterial infections and are undergoing surgery for post-sternotomy wound infections, mediastinitis, or infected prosthetic joints .

The main questions it aims to answer are:

• What is the concentration of delafloxacin in the blood plasma?
• What is the concentration of delafloxacin in different body tissues, including soft tissue, tissue around a prosthetic implant, joint fluid (synovial fluid), and bone ?
• How does the concentration of the drug in the blood compare to its concentration in the tissues?
• Do patient factors such as age, body weight, and kidney function affect the drug's levels in the body?

Participants will:

• Continue to receive delafloxacin (300mg intravenously every 12 hours) as prescribed by their treating physician for their infection.
• Allow researchers to draw 5 peripheral blood samples (about 10 mL total) at specific times (15 minutes, 1 hour, 3 hours, 5-7 hours, and 11 hours) after the end of a single delafloxacin infusion.
• Allow researchers to collect small amounts of tissue and joint fluid for testing during their already planned surgical procedure.

Inclusion Criteria:

• Participant is willing and able to give informed consent for participation in the study, and to be concurrently enrolled in the Institutional Infectious Disease Biobank (INDI-REBIO, NCT06418048)

• >18 years-old

• eGFR of > 80 mL/min/1,73m2

• Receiving delafloxacin 300mg q12h IV according to treating physician's choice and good clinical practice or available guidelines with bacterial skin and skin structure infection and with

  1. post-sternotomy wound infection and/or mediastinitis undergoing surgical debridement
  2. prosthetic joint infections undergoing surgical debridement or prosthetic joint removal (either one-stage, e.g. when the Infected prosthesis is removed and a new one is implanted in the same surgery, or two-stage, when the Infected prosthesis is removed, followed by a period of antibiotics, then a new prosthesis is implanted in a second surgery).

Exclusion criteria:

• Patients who received other quinolones (oral or IV) in the week preceding the sample collection
• Patients who decline or are unwilling to participate in serial blood draws at all five designated time points.
• Pregnant or lactating women

Patients admitted to the hospital receiving delafloxacin according to treating physician's choice and good clinical practice or available guidelines with bacterial skin and skin structure infection and with:

1) post-sternotomy wound infection and/or mediastinitis undergoing surgical debridement or

1) prosthetic joint infections undergoing surgical debridement or prosthetic joint removal (either one-stage, e.g. when the Infected prosthesis is removed and a new one is implanted in the same surgery, or two-stage, when the Infected prosthesis is removed, followed by a period of antibiotics, then a new prosthesis is implanted in a second surgery).