Biofilm and inflammation. Study of the antimicrobial and immunomodulatory capacity of Lactiplantibacillus plantarumon on Staphylococcus aureus strains isolated from diabetic foot ulcers.

RACHID M; WERENITSKY C; ARGAÑARAZ AYBAR N; DOMÍNGUEZ PAREDES G; CALVO G; BUZZOLA F; NISO S

Congreso; LXXI Reunión Científica Anual de la Sociedad Argentina de Inmunología; 2023

Objectives: The objetives of this study were to (i) study the antimicrobialproperties of Lactiplantibacillus plantarum (Lp) and its supernatant (SLp) on thevirulence factors of methicillin-resistant Staphylococcus aureus (MRSA) strainsisolated from diabetic foot ulcers and (ii) to investigate the effect of Lp and itssupernatant on the microbicity activity of polymorphonuclearcells (PMNs)infected with MRSA. Material and methods: Diabetic patients with ulcers weretreated with a topical application of Lp. This study was approved by the HospitalEthics Committee. Biopsies were taken at day 0, 10 and 30 post-treatment.Standard bacteriology techniques were applied for the isolation and identificationof microorganisms that infect wound. MRSA strains were identified from biopsiesobtained before, during and post-treatment. Antibiotic susceptibility wasdetermined accordingto CLSI international standards. Quantitative real-time PCRwas utilized to determine genes expression that code for adhesión virulencefactors (fnbA,sdrC, eap, emp, cna, clfA).The inhibition capacity of Lp and itssupernatant (SLp) on the biofilms of MRSA strains was studied with the O´Tooleand Kolter technique and viability was also determined with MTT assay.Antimicrobial susceptibility profiles of MRSA and the growth inhibition capacity ofLp and SLp were determined using the disk-diffusion method. PMNs were isolatedfrom the circulanting blood of the patients. PMNs were stimulated with Lp andculture supernatant to perform the following tests: phagocytosis by flowcytometry,NETosis by fluorometry and microbicidal activity. Results: An increase in theexpression of the eap, fnbA and clfA genes of the MRSA strains obtained fromthe biopsies of day 0 and 15 compared to the biopsies of day 30 was observed.In this study all MRSA strains isolates were identified as biofilms producers. Lpand SLp inhibit the MRSA biofilm after 18 h of incubation. Significant differenceswere observed between the MRSA biofilm without treatment and the biofilmtreated with Lp (100% vs 35%