518 Relationship of Microbiome, Antimicrobial Resistance, and Wound Closure in >90% Burn Patients

Abstract

Abstract Introduction Patients with 90% or greater total body surface area (TBSA) burns of face many unique challenges, including prolonged open wounds and antibiotic use. Furthermore, increased antibiotic use can be associated with increased antibiotic resistance. Despite the commonality, the relationship between prolonged wound closure (months) combined with prolonged duration of antibiotic use (months) has not been fully explored. The specific aim of this study was to examine the evolution of burned patients’ microbiome over time in association with wound healing and antibiotic use. Methods We conducted a retrospective review of all patients admitted to our ABA-verified burn center from 2010-present with 90% TBSA or greater burns who survived to discharge. Demographic data, length of stay, percentage monthly wound closure (including donor sites), microbial culture data of bacteria, yeast, fungus, and mold (YFM), antibiotic susceptibilities, and systemic antimicrobial agents administered were recorded. Statistical analysis was performed using Pearson correlation coefficient. Results Two patients met inclusion criteria. Patient A (PtA), a 36 year old (yo) female with 95% TBSA burns and Patient B (PtB), a 45 yo male with 90% TBSA burns. Patients spent a combined 766 days (PtA 425, PtB 341) as inpatients. 347 separate positive cultures were analyzed, 180 of which were bacterial. 15 distinct species of bacteria were cultured (8 PtA, 9 PtB), along with 4 subtypes of Pseudomonas aeruginosa, and 9 distinct YFM (6 PtA, 6 PtB). Increasing antibiotic resistance was found in 57% (PtA) and 71% (PtB) of bacterial species. Pseudomonas was the most commonly isolated organism in 65% (n=118) of cultures. The relationships between percent wound closure, daily antibiotic use, and Pseudomonas antibiotic resistance are shown in the Graph below. There was a strong correlation between wound closure of >50% with decreased amount of antibiotics used per day (PtA 0.83, PtB 0.86) and decreasing % of Pseudomonas antibiotic resistance (PtA 0.66, PtB 0.8). Conclusions Antibiotic resistance increases over time and efforts should be taken to decrease number of antibiotics administered. As wound closure passes a certain threshold, the number of antibiotics needed decreases, and Pseudomonas antibiotic resistance appears to decrease as well. Applicability of Research to Practice Recognition of different environmental pressures for bacteria may point to changes in microbial resistance patterns and thus clinical management.