Lactic acid bacteria with antimicrobial activity against Acinetobacter baumannii.

CECILIA RODRÍGUEZ; CAMILA LEAL; MARIA SOLEDAD RAMÍREZ; RAÚL RAYA

Washington, DC

Congreso; ASM Microbe; 2022

ASM

Acinetobacter baumannii (AB) is an important nosocomial pathogen with a high ability topersist in the hospital environment and to rapidly acquire resistance to severalantimicrobials. 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, theantimicrobial activity of eight lactic acid bacteria (LAB) strains (Latilactobacillus curvatusCRL705; Limosilactobacillus mucosae CRL573; Lacticaseibacillus casei BL23;Lactobacillus acidophilus CRL641; Fructobacillus tropaeolis CRL2034, Lacticaseibacillusrhamnosus CRL1505 y CRL75 y Limosilactobacillus reuteri CRL1101) against AB118was evaluated. The inhibitory activity of cell pellets and their supernatants weredetermined, 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 LABstrains 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 ofAB118, assessed in co-culture with probiotic L. casei BL23, showed 6-log decrease inAB118 CFU/mL and changes in AB118 colony morphology. While, the cell viability ofAB118, assessed with supernatant or filtrate from BL23/AB118 co-culture, showed 1-2 logdecrease in AB118. Thus, the interaction between LAB/AB cells seems to be critical forantimicrobial activity. Future trials are needed to elucidate the mechanism involved.