Interspecies interactions in mixed-species biofilms formed by Enterococcus faecalis and gram-negative bacteria isolated from polymicrobial diabetic foot ulcers

• Published in: Biofouling (Chur, Switzerland) Vol. 39; no. 5; pp. 579 - 590
• Main Authors: Mariani, Florencia, Juarez, Guillermo E., Barberis, Claudia, Veiga, Florencia, Vay, Carlos, Galvan, Estela M.
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 28.05.2023; Taylor & Francis Ltd
• Subjects: Agar; Bacteria; Biofilms; Colonization; Diabetes mellitus; Diabetic foot ulcer; E coli; Enterococcus faecalis; Escherichia coli; Gram-negative bacteria; Microbiological strains; mixed-species biofilm; Morganella morganii; Nutrients; Plantar ulcers; polymicrobial infection; Pseudomonas aeruginosa; Ulcers; Enterococcus faecalis; Pseudomonas aeruginosa; mixed-species biofilm; polymicrobial infection; Diabetic foot ulcer; Escherichia coli
• ISSN: 0892-7014; 1029-2454
• DOI: 10.1080/08927014.2023.2236949

Diabetic foot ulcers (DFU) are exacerbated by bacterial colonisation. Here, a high prevalence of Enterococcus faecalis was observed in DFU patients from an Argentinean hospital. E. faecalis was frequently co-isolated with Escherichia coli, Morganella morganii, and Pseudomonas aeruginosa. The effect of interspecies interactions on bacterial growth was investigated in mixed-species macrocolony biofilms developed in Lubbock-Glc-agar. Similar cell counts were found for E. faecalis and M. morganii growing in mixed and single-species biofilms. An E. faecalis strain showed 1 Log higher cell counts in mixed biofilms with E. coli. Remarkably, E. faecalis strains showed 2 to 4 Log higher cell counts in mixed biofilms with P. aeruginosa. This effect was not observed in planktonic growth or biofilms developed in tryptic soy agar. The present findings reveal bacterial interactions that benefit E. faecalis in mixed-species biofilms, mainly with P. aeruginosa, in a medium that partially mimics the nutrients found in DFU.