Lactic acid bacteria with antimicrobial activity against Acinetobacter baumannii

CECILIA RODRÍGUEZ; LEAL CAMILA; RAMIREZ MARIA SOLEDAD; RAYA RAUL RICARDO

Washington, DC

Congreso; ASM Microbe; 2022

American Society of Microbiology

Acinetobacter baumannii (AB) is an important nosocomial pathogen with a high ability to persist in the hospital environment and to rapidly acquire resistance to several antimicrobials. Thus, it becomes difficult to treat AB infections with available antibiotics. New therapeutic alternatives for the control of AB are an urgent priority. In this work, the antimicrobial activity of eight lactic acid bacteria (LAB) strains (Latilactobacillus curvatus CRL705; Limosilactobacillus mucosae CRL573; Lacticaseibacillus casei BL23; Lactobacillus acidophilus CRL641; Fructobacillus tropaeolis CRL2034, Lacticaseibacillus rhamnosus CRL1505 y CRL75 y Limosilactobacillus reuteri CRL1101) against AB118 was evaluated. The inhibitory activity of cell pellets and their supernatants were determined, respectively, by the soft-agar overlay and the well diffusion methods. R values (Inhibition diameter - Spot diameter) were determined and interpreted as R6 mm (high inhibition). The pellets of all LAB strains assayed, except F. tropaeolis, showed R values >6 mm (with diameters of inhibition >20mm). No inhibitory activity was observed for all supernatants. The cell viability of AB118, assessed in co-culture with probiotic L. casei BL23, showed 6-log decrease in AB118 CFU/mL and changes in AB118 colony morphology. While, the cell viability of AB118, assessed with supernatant or filtrate from BL23/AB118 co-culture, showed 1-2 log decrease in AB118. Thus, the interaction between LAB/AB cells seems to be critical for antimicrobial activity. Future trials are needed to elucidate the mechanism involved.