• Jennifer K Plichta, Casey J Holmes, Vanessa Nienhouse, Michelle Puszynski, Xiang Gao, Qunfeng Dong, Huaiying Lin, James Sinacore, Michael Zilliox, Evelyn Toh, David E Nelson, Richard L Gamelli, and Katherine A Radek.
• 1Burn and Shock Trauma Research Institute, Loyola University Chicago, Health Sciences Campus, Maywood, IL. 2Department of Surgery, Loyola University Chicago, Health Sciences Campus, Maywood, IL. 3Department of Public Health Sciences, Stritch School of Medicine, Loyola University Chicago, Health Sciences Campus, Maywood, IL. 4Center for Biomedical Informatics, Loyola University Chicago, Health Sciences Campus, Maywood, IL. 5Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN.
• Crit. Care Med. 2017 Jun 1; 45 (6): e543-e551.

ObjectivesCharacterization of urinary bacterial microbiome and antimicrobial peptides after burn injury to identify potential mechanisms leading to urinary tract infections and associated morbidities in burn patients.DesignRetrospective cohort study using human urine from control and burn subjects.SettingUniversity research laboratory.PatientsBurn patients.InterventionsNone.Measurements And Main ResultsUrine samples from catheterized burn patients were collected hourly for up to 40 hours. Control urine was collected from "healthy" volunteers. The urinary bacterial microbiome and antimicrobial peptide levels and activity were compared with patient outcomes. We observed a significant increase in urinary microbial diversity in burn patients versus controls, which positively correlated with a larger percent burn and with the development of urinary tract infection and sepsis postadmission, regardless of age or gender. Urinary psoriasin and β-defensin antimicrobial peptide levels were significantly reduced in burn patients at 1 and 40 hours postadmission. We observed a shift in antimicrobial peptide hydrophobicity and activity between control and burn patients when urinary fractions were tested against Escherichia coli and Enterococcus faecalis urinary tract infection isolates. Furthermore, the antimicrobial peptide activity in burn patients was more effective against E. coli than E. faecalis. Urinary tract infection-positive burn patients with altered urinary antimicrobial peptide activity developed either an E. faecalis or Pseudomonas aeruginosa urinary tract infection, suggesting a role for urinary antimicrobial peptides in susceptibility to select uropathogens.ConclusionsOur data reveal potential links for urinary tract infection development and several morbidities in burn patients through alterations in the urinary microbiome and antimicrobial peptides. Overall, this study supports the concept that early assessment of urinary antimicrobial peptide responses and the bacterial microbiome may be used to predict susceptibility to urinary tract infections and sepsis in burn patients.

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