Hello and Welcome to ‘Ask A Doctor’ service.
I have reviewed your query and here is my advice.
As the skin lesion is involving only of the groin area, the relation with
IV antibiotic seems unlikely. Yes, it can be in concern with possible central line insertion in groin area if done during hospitalization 3 weeks ago for
ischemic colitis. It can be a skin manifestation of immune mediated event of colitis. Management will be consisting of
1) Local care with sterile dressing.
2) Systemic antibiotic ( IV or oral ) as per the clinician concern.
3) Maintenance of hydration.
4)
Analgesic coverage with injection or tablet.
5) Control of blood sugar.
Hope I have answered your query.
Let me know if I can assist you further.