Current status of postoperative infections after digestive surgery in Japan: The Japan Postoperative Infectious Complications Survey in 2015

Abstract Aim To survey postoperative infections (PI) after digestive surgery. Methods This survey, conducted by the Japan Society of Surgical Infection, included patients undergoing digestive surgery at 28 centers between September 2015 and March 2016. Data collected included patient background characteristics, type of surgery, contamination status, and type of PI, including surgical site infection (SSI), remote infection (RI), and antimicrobial‐resistant (AMR) bacterial infections and colonization. Results Postoperative infections occurred in 10.7% of 6582 patients who underwent digestive surgery (6.8% for endoscopic surgery and 18.7% for open surgery). SSI and RI, including respiratory tract infection, urinary tract infection, antibiotic‐associated diarrhea, drain infection, and catheter‐related bloodstream infection, occurred in 8.9% and 3.7% of patients, respectively. Among all PI, 13.2% were overlapping infections. The most common overlapping infections were incisional and organ/space SSI, which occurred in 4.2% of patients. AMR bacterial infections occurred in 1.2% of patients after digestive surgery and comprised 11.5% of all PI. Rate of AMR bacterial colonization after digestive surgery was only 0.3%. Conclusion Periodic surveillance of PI, including AMR bacteria, is necessary for a detailed evaluation of nosocomial infections.

Remote infections (RI) can occur at various sites after surgery, 5 such as the respiratory and urinary tracts, as well as drain infection, and include antibiotic-associated diarrhea and catheter-related bloodstream infection. 12 In certain cases, RI can be associated with antimicrobial-resistant (AMR) bacterial infection and colonization, which have become an increasingly significant problem, with increased global incidence and emergence among communityacquired infections. 9,[13][14][15][16] Therefore, investigation of the prevalence of RI as well as AMR bacterial infections and colonization is important for better understanding of this global problem.
Herein, we present the results of the Japan Postoperative Infectious Complications Survey in 2015 (JPICS-15), which examined the incidences and types of PI after digestive surgery. We also determined the rates of specific PI, including SSI and RI as well as AMR bacterial infections and colonization.

| ME THODS
This voluntary survey was conducted by the Japan Society for Surgical Infection at 28 centers, which included 16 university hospitals, 11 general hospitals, and one cancer center. A detailed list of the participating facilities is given in the Acknowledgments section. Patient data (ie, age, gender, type of surgical procedure, contamination status, PI, isolated bacteria, presence and status of AMR bacteria, and prognosis) were prospectively accumulated between Confirmation of bacterial infection was based on the isolation of bacteria from specimens with inflammatory findings of high fever and elevated white blood cell counts and C-reactive protein levels, whereas bacterial colonization was defined as the presence of low-volume bacteria, such as more than 1+ by qualitative analysis, in the absence of any inflammatory findings.   Of all PI, SSI and RI accounted for 583 (8.9%) and 244 (3.7%), respectively. Incidence rates of incisional SSI, organ/space SSI, RTI, UTI, antibiotic-associated diarrhea, catheter-related bloodstream infection, drain infection, and bacteremia of unknown origin according to surgical procedure are shown in Figure 2.
The most common overlapping infections were incisional and organ/ space SSI, which were detected in 30 (4.2%) patients.
Data on AMR bacterial infection and colonization are shown in Figure 3. VRE and MDR-GN were not isolated during the study period. Infections with AMR bacteria were detected in 81 patients, which included 1.2% of patients after digestive surgery and 11.5% of PI.
AMR bacteria were isolated from five patients (one CD colitis, two MRSA, and two ESBL-producing Enterobacteriaceae). We also analyzed overlapping PI. The most common postoperative overlapping infections were incisional and organ/space SSI.

| D ISCUSS I ON
Therefore, the most important problem regarding the prevention of PI is reducing the incidences of incisional and organ/space SSI. There are several strategies that surgeons can implement to prevent SSI. 39,40 Antimicrobial-resistant bacterial infection and colonization, especially after surgery, is a major global clinical problem that is expected to continue to increase in parallel with the increase in the elderly population. The AMR bacterial infection rates in the present This situation may have been influenced by the incidence of postoperative SSI and RI. However, the main focus of this survey was to identify the actual factors underlying the occurrence of SSI, RI, and AMR infection and colonization after digestive surgery in Japan.
In conclusion, PI, including SSI and RI, in patients after digestive surgery, as well as the incidence of AMR bacterial infection and colonization, were evaluated. Periodic survey of PI, including AMR bacterial surveillance, is necessary for a detailed evaluation of nosocomial infections. Future multicenter prospective randomized control trials based on this surveillance will be useful for a detailed evaluation of PI.

ACK N OWLED G M ENTS
We would like to extend our deep appreciation to the participants of this survey. The participating institutions and chief participants were follows: Department of Gastroenterological Surgery, Fukuoka University (S. Takeno), Division of Surgery, Fujinomiya City