Aim of prospective randomized a placebo controlled study is to prove that in case of acute surgical procedure due to appendicitis, ileus of small bowel and perforation of small bowel and stomach appropriately administered antibiotic prophylaxis is effective with lower incidence of infection in surgical site and comparable risk of development of other nosocomial infections versus group without antibiotic prophylaxis. Secondary aim is to determine risk of developing nosocomial infection in the above mentioned group of patients, identify group of patients which does not benefit from prophylaxis, and compile financial costs for antibiotic prophylaxis and treatment of nosocomial infections and thus the background for the recommended procedure with regards that such prospective study does not exist in the Czech Republic.