Epidemiological analysis of intra-abdominal infections in Italy from the Italian register of complicated intra-abdominal infections—the IRIS study: a prospective observational nationwide study

Background: Intra-abdominal infections (IAIs) are common and severe surgical emergencies associated with high morbidity and mortality. In recent years, there has been a worldwide increase in antimicrobial resistance associated with intra-abdominal infections, responsible for a significant increase in mortality rates. To improve the quality of treatment, it is crucial to understand the underlying local epidemiology, clinical implications, and proper management of antimicrobial resistance, for both community- and hospital-acquired infections. The IRIS study (Italian Register of Complicated Intra-abdominal InfectionS) aims to investigate the epidemiology and initial management of complicated IAIs (cIAIs) in Italy. Material and method: This is a prospective, observational, nationwide (Italy), multicentre study. approved by the coordinating centre ethic committee (Local Research Ethics Committee of Pisa (Prot n 56478//2019). All consecutively hospitalized patients (older than 16 years of age) with diagnosis of cIAIs undergoing surgery, interventional drainage or conservative treatment have been included. Results: 4530 patients included from 23 different Italian hospitals. Community Acquired infection represented the 70.9% of all the cases. Among appendicitis, we found that 98.2% of the cases were community acquired (CA) and 1.8% Healthcare-associated (HA) infections. We observed that CA represented the 94.2% and HA 5.8% of Gastro Duodenal perforation cases. The majority of HA infections were represented by colonic perforation and diverticulitis (28.3%) followed by small bowel occlusion (19%) and intestinal ischemia (18%). 27.8% of patients presented in septic shock. Microbiological Samples were collected from 3208 (70.8%) patients. Among 3041 intrabdominal sample 48.8% resulted positive. The major pathogens involved in intra-abdominal infections were found to be E.coli (45.6%). During hospital stay, empiric antimicrobial therapy was administered in 78.4% of patients. Amoxicillin/clavulanate was the most common antibiotic used (in 30.1% appendicitis, 30% bowel occlusion, 30.5% of cholecystitis, 51% complicated abdominal wall hernia, 55% small bowel perforation) followed by piperacillin/tazobactam (13.3% colonic perforation and diverticulitis, 22.6% cholecystitis, 24.2% intestinal ischemia, 28.6% pancreatitis). Empiric antifungal therapy was administered in 2.6% of patients with no sign of sepsis, 3.1% of patients with clinical sign of sepsis and 4.1% of patients with septic shock. Azoles was administered in 49.2% of patients that received empiric antifungal therapy. The overall mortality rate was 5.13% (235/4350). 16.5% of patients required ICU (748/4350). In accordance with mortality, it is important to highlight that 35.7% of small bowel perforation, 27.6% of colonic perforation and diverticulitis, 25.6% of intestinal ischemia and 24.6% of gastroduodenal complications required ICU. Conclusion: Antibiotic stewardship programs and correct antimicrobial and antimycotic prescription campaigns are necessary to ulteriorly improve the adequacy of drug usage and reduce the resistances burden. This will help in improving the care and the cure of the next generations.