Antimicrobial activity of Lactobacillus spp against uropathogenic bacteria

ROBLES, ROCÍO; FARIZANO, JUAN VICENTE; RAPISARDA, VIVIANA A.; HEBERT, ELVIRA M.; GRILLO PUERTAS, MARIANA; VILLEGAS, JOSEFINA M.

Mendoza

Congreso; SAIB 2022; 2022

SAIB

Urinary tract infections (UTI) remain a major medical problem in terms of the number of people afflicted each year. Althoughantimicrobial therapy is generally an effective way to eradicateseradicate these infections, a current problem is the increasingemergence of microbes resistant to antimicrobial agents. Uropathogens (UP) usually develop biofilms, resulting in persistent andchronic infections that are associated with resistance to antimicrobial therapy. The use of lactobacilli has been proposed as analternative to prevent UTIs in the era of antibiotic resistance. Here, the potential antibacterial and antibiofilm activities ofsupernatants derived from five lactobacilli strains against different clinical urinary strains, isolated from patients of a public hospitalof Tucumán, were investigated. First, Lactiplantibacillus paraplantarum CRL 1905, L. brevis CRL 1942, L. fermentum CRL 973,L. helveticus ATCC974 and L. acidophilus ATCC 4356 strains were grown in MRS for 24 h at 37 °C; cell-free supernatants (CFS)were obtained by filtration. Inhibitory activities of these CFS were assayed by the agar well diffusion assay. Based on the inhibitionhalo, all CFS displayed a strong antimicrobial ability against the different UP strains, but with variable degrees. Staphylococcusaureus EC1 and Escherichia coli EC7 strains were selected for further studies. The minimum inhibitoryvolume (MIV) of the different CFS against the indicated strains were determined using a brothmicrodilution assay. The five CFS inhibited both pathogenic bacteria, with a MIV of 25 % (v/v).However, the minimal bactericidal volume (MBV) values of these CFS were ≥ 50 % (v/v), killing99.99 % of the bacteria. The effect of all CFS against biofilm formation by EC1 and EC7 strainswere determined. Dilutions up to 6 % of the tested CFS significantly inhibited biofilmformation, when compared with the untreated control, observing an antibiofilm activity in aconcentration-dependent manner. In addition, the biofilm disassembly capacity of all CFS on72 h- established biofilms of the UP strains was assessed. When compared with the untreatedcontrol, a reduction of the integrity of biofilms using 10-fold concentrated CFS was observed.Finally, to determine the nature of the antimicrobial compound/s, the different CFS weresubmitted to heat, proteinase K and tripsine treatment, or neutralization. It was observedthat all CFS lost their antagonistic properties after pH neutralization, suggesting an acidicnature of the metabolite/s. Our results demonstrate that CFS obtained from five lactobacillistrains secrete products that inhibit growth, reduce biofilm formation and removeestablished biofilm of different UP, suggesting their potential application for controlling orpreventing colonization in UTIs.