<prompt> In a surgical patient, the causes of non surgical infection are all, exceptLower respiratory tract infectionWound infectionClostridium difficile diarrheaUTI  <response>: Surgical site infections SSIs are the third most frequently reported nosocomial infection, first one being pneumonia and the second, catheter-related including urinary tract infection.SSI within 24 hours is caused by clostridia and streptococci.SSI after 48 hours 5 days is caused by gram -ve and other bacteria.Clostridium difficile diarrhea occurrence is due to administration of various antibiotics.Reference: Manipal Manual of Surgery 4th ed page no 26, 28 