Surgical Site Infection

A 42-year-old woman undergoes emergency appendicectomy for perforated appendicitis. On postoperative day 3, she develops fever and abdominal distension. Clinical examination reveals localized right lower quadrant tenderness and a palpable mass. Which investigation is most appropriate to confirm the diagnosis of postoperative intra-abdominal abscess?

A 52-year-old man undergoes elective open cholecystectomy for chronic cholecystitis. On postoperative day 5, he develops fever (38.5°C), wound erythema, and purulent discharge from the surgical incision. Which is the most common causative organism of this surgical site infection?

A 38-year-old woman develops a surgical site infection following an open appendectomy performed 4 days ago. Culture of wound fluid grows multiple organisms including gram-negative rods and anaerobes. Which is the most common organism isolated from SSIs of the lower gastrointestinal tract?

Regarding the classification and risk factors for surgical site infections (SSI), all of the following statements are correct EXCEPT:

A 38-year-old woman undergoes an emergency cesarean section for fetal distress. The operative time is 90 minutes; estimated blood loss is 800 mL. Prophylactic cefazolin 2 g IV was given at induction. On postoperative day 5, she presents with fever (39.2°C), abdominal pain, and serous drainage from the lower abdominal incision. Ultrasound shows a 4 cm fluid collection adjacent to the fascia. Blood culture is pending. What is the most appropriate management?