Gram-Negative Bacilli Blood Stream Infection in Patients with Severe Burns: Microbiological and Clinical Evidence from a 9-Year Cohort

Bloodstream infection is one of the most important and increasing complications in patients with severe burns. Most of the species affecting this population are Gram-negative bacilli that exhibit antimicrobial resistance. We conducted this study to determine the antimicrobial susceptibility profile and resistance mechanisms of these bacterial infections and their clinical associations on morbidity and mortality. We analyzed a retrospective cohort of burn patients. All patients included in this study had monobacterial blood stream infections during their hospital stay. We performed phenotypic and genotypic tests to determine the antimicrobial resistance mechanism and profile of each strain. Univariate and multivariate logistic regression analysis was performed between variables. We found 109 patients with monobacterial bacteremia. spp. (50.7%), (46.4%), and spp. (13.8%) were the most common causative microorganisms. The spp. isolates showed resistance to imipenem (81.5%), mainly by class A and class B carbapenemases. The isolates conferred resistance to imipenem (56.2%), mainly by class D carbapenemases. One quarter of spp. showed resistance to 3rd generation cephalosporins. We also observed that a total body surface area greater than 40% and three or more different types of invasive procedures might be related to increased mortality. Multidrug resistance is highly present. The extent of the burned area and a high number of different types of invasive procedures had an impact in decreasing survivorship in burn patients with bacteremia.