In this prevalence study the overall burden of HAI in a large patient population exposed to recent surgery were assessed and the risk profile and HAI rates were compared to those in all inpatients not exposed to surgery. 10.6 % patients exposed to surgery had HAI, but only 4.2 % patients nonexposed to surgery had HAI. Prevalence of surgical site infection (SSI) was 5.4%. Healthcare-associated infections prevalence excluding SSI was 6.5% in patients with surgery and 4.7% in those without (P < 0.0001). Patients exposed to surgery carried less intrinsic risk factors for infection than those nonexposed, but more extrinsic risk factors. Exposure to surgery independently predicted an increased risk of HAI (odds ratio 2.43; 95% CI 2.0–3.0).