PurposeSuperficial surgical site infections (SSI) are a common complication after abdominal surgery. Additionally, multidrug-resistant organisms (MDRO) have shown an increasing spread in recent years with a growing importance for health care. As there is varying evidence on the importance of MDRO in different surgical fields and countries as causative agents of SSI, we report our findings of MDRO-caused SSI.MethodsWe assembled an institutional wound register spanning the years 2015–2018 including all patients with abdominal surgery and SSI only, including demographics, procedure-related data, microbiological data from screenings, and body fluid samples. The cohort was examined for the frequency of different MDRO in screenings, body fluids, and wound swabs and assessed for risk factors for MDRO-positive SSI.ResultsA total of 138 out of 494 patients in the register were positive for MDRO, and of those, 61 had an MDRO isolated from their wound, mainly multidrug-resistantEnterobacterales(58.1%) followed by vancomycin-resistantEnterococcusspp. (19.7%). As 73.2% of all MDRO-carrying patients had positive rectal swabs, rectal colonization could be identified as the main risk factor for an SSI caused by a MDRO with an odds ratio (OR) of 4.407 (95% CI 1.782–10.896,p= 0.001). Secondly, a postoperative ICU stay was also associated with an MDRO-positive SSI (OR 3.73; 95% CI 1.397–9.982;p= 0.009).ConclusionThe rectal colonization status with MDRO should be taken into account in abdominal surgery regarding SSI prevention strategies.Trial registrationRetrospectively registered in the German register for clinical trials (DRKS) 19th December 2019, registration number DRKS00019058.