Intestinal Colonization and Subsequent Nosocomial Infection with Carbapenem-Resistant Organisms in a PICU: Risk Factors and Molecular Homology Analysis

Background: Rates of carbapenem-resistant organism (CRO) colonization and infection are rising in pediatric intensive care units (PICUs), mainly due to underlying comorbidities, frequent invasive procedures, prolonged hospitalization, and extensive use of broad-spectrum antibiotics. Colonized patients can act as reservoirs for nosocomial transmission of drug-resistant bacteria, posing a serious threat to other children and healthcare workers. Prevention and control of CRO are therefore of urgent clinical importance. Methods: Based on active screening measures, we analyzed risk factors for intestinal CRO colonization and subsequent nosocomial infection in critically ill children. Pulsed-field gel electrophoresis (PFGE) was used to determine molecular homology between colonizing and infecting strains isolated from the same patient. Results: A total of 1069 children were admitted to our PICU between January 2021 and September 2022. Seventy-seven cases of intestinal CRO colonization were detected, with a colonization rate of 7.2%. Of these colonized children, 15 developed subsequent CRO infection, and PFGE confirmed that the infecting strains were homologous to the colonizing ones. Independent risk factors for CRO colonization included underlying neuromuscular disease (OR 7.048, 95% CI 3.003– 16.545, P< 0.001) and longer hospital stay (OR 1.063, 95% CI 1.034– 1.092, P< 0.001). Among colonized children, independent risk factors for subsequent nosocomial infection were carbapenem exposure (OR 4.041, 95% CI 1.310– 12.470, P=0.014), absence of contact isolation (OR 0.033, 95% CI 0.002– 0.496, P=0.010), and longer hospital stay (OR 1.083, 95% CI 1.002– 1.170, P=0.045). Conclusion: Intestinal CRO colonization significantly increases the risk of subsequent homologous nosocomial infection in PICU children. Rational carbapenem use,aprompt contact isolation following colonization and shorten hospitalization time are crucial strategies to reduce CRO-related nosocomial infections.