<prompt> Regarding antibiotics true are :No prophylaxis for clean contaminated surgeryNo prophylaxis for gastric ulcer surgeryProphylaxis for colorectal surgeryLocal irrigation with antibiotic contraindicated when systemic antibiotics given.  <response>: Surgical site infections or also ka wound infectionsare infections of the tissue, organs or spaces exposed by surgeons during the performance of an invasive procedure.they are classified as belowClassification of Surgical WoundsClean Wound Class Iinclude those in which no infection is present; only skin microflora potentially contaminate the wound. No hollow viscus is entered. No inflammationexamples: Hernia repair, breast biopsyCleancontaminated wounds Class IIinclude those in which a hollow viscus such as the respiratory, alimentary or genitourinary tracts with indigenous bacterial flora is opened, but under controlled circumstances without significant spillage of contents. No inflammation.examples: Cholecystectomy, elective GI surgery.Contaniinated.wounds Class IIIinclude open accidental wounds encountered early after injury, those with the extensive introduction of bacteria into a normally sterile area of the body due to major breaks in sterile technique eg. open cardiac massage; uncontrolled spillage of viscous contents such as from the intestine. Inflammation is apparentexamples: Penetrating abdominal trauma, large tissue injury, enterotomy during bowel obstruction.Dirty wounds Class IVinclude traumatic wounds in which a significant delay in treatment has occurred and in which necrotic tissue is present. Includes wounds in which pus is present. Includes those wounds created to access a perforated viscus accompanied by a high degree of contamination. Severe inflammation is seenexamples : Perforated diverticulitis, necrotizing soft tissue infectionVarious steps are described for the prevention of SSIs, but we will discuss those related to use of antibiotics onlyUse of antibiotics as nrovhvlaxis of SSIs 