Incidence, risk factors and outcome of multi-drug resistant Acinetobacter baumannii nosocomial infections during an outbreak in a burn unit

Background: Multidrug-Resistant Acinetobacter baumannii (MR-AB) can cause outbreaks in burn units. We aimed to study the incidence, risk factors and outcome of MR-AB infections in a burn unit (BU). Methods: A prospective study was conducted from April to November, 2014 during an outbreak in a BU in Paris. Weekly surveillance cultures were performed to determine MR-AB colonization. MR-AB nosocomial infections, discharge or death without MR-AB infection were considered as competing events. To identify risk factors for MR-AB infection, baseline characteristics and time-dependent variables were investigated in univariate analyses using Cox models. Results: Eighty-six patients admissions were analyzed during the study period. Among them, 15 (17%) acquired MR-AB nosocomial infection. Median time to infection was 22 days (interquartile range: 10-26 days). Cumulative incidence of MR-AB infections was 15% at 28 days (95% CI = 8-24). Risk factors for MR-AB infection in univariate analysis were SAPS II (Hazard Ratio (HR): 1.08; 95% CI: 1.05-1.12; P < 0.0001) and ABSI (Abbreviated Burn Severity Index) scores (HR: 1.32; 95% CI: 1.12-1.56; P = 0.001), MR-AB colonization (HR: 10.2; 95% CI: 2.05-50.3; P = 0.004), invasive procedures (ventilation, arterial and/or venous catheter) (P = 0.0001) and >= 2 skin grafts (HR: 10.2; 95% CI: 1.76-59.6; P = 0.010). MR-AB infection was associated with an increased risk of death (HR: 7.11; 95% CI: 1.52-33.2; P = 0.013) and longer hospital stay with a median estimated increase of 10 days (IQR: 6; 14). Conclusions: Incidence of MR-AB nosocomial infection was high during this outbreak, and was associated with prolonged hospitalization and increased risk of death. High patient severity scores, prior MR-AB colonization, invasive procedures and repeated skin grafts were associated with an increased risk of nosocomial infection. (c) 2018 Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).