Table 2 Definition of endpoints

Primary composite endpoint

Cumulative incidence of deep surgical site infection and/or mortality within 30 days after surgery

Deep SSI will be diagnosed according to the CDC criteria for surgical site infections [37]. Deep SSI includes both deep incisional SSI and organ/space SSI

Secondary endpoints

30 days after surgery

Cumulative incidence of superficial SSI

Superficial and deep SSIs will diagnosed according to the CDC criteria for surgical site infections [37]

Cumulative incidence of deep SSI

All-cause mortality

Cumulative incidence of bacteremia

Blood cultures positive for microorganisms

Cumulative incidence of infection with Clostridium difficile

Stool sample positive for C. difficile toxins

Cumulative incidence of infection with HRE

Clinical cultures positive for ESBL or carbapenemase-producing Enterobacteriaceae or Enterobacteriaceae resistant to quinolones and/or aminoglycosides [38]

Cumulative incidence of rectal colonization with HRE and colistin resistant species

Rectal swabs positive for HRE or colistin resistant species, measured at baseline and 30 days after surgery

Cumulative incidence of anastomotic leakage

Clinical and/or radiological evidence of leakage requiring surgical or radiological reintervention

Cumulative incidence of re-laparotomy

Reoperation in the abdominal region

In-hospital use of antibiotics

Defined as “days on therapy”

6 months after surgery

All-cause mortality

Quality of life

Measured with the RAND-36 questionnaire [39]

Length of hospital stay

In days, including all readmissions

Length of ICU stay

In days, including all readmissions

In-hospital costs