Antimicrobial Synergy between Aminoglycosides and Licorice Extract in Listeria monocytogenes

Area of Science:

• Microbiology
• Pharmacology
• Food Science

Background:

• Listeria monocytogenes causes severe infections with high fatality rates, necessitating improved treatments.
• Current therapies for listeriosis, like ampicillin and gentamicin, lack proven synergy.
• There is a need for novel strategies to combat antibiotic resistance in L. monocytogenes.

Purpose of the Study:

• To investigate the potential synergistic antimicrobial effects of licorice extract with aminoglycosides against Listeria monocytogenes.
• To evaluate if licorice extract can restore susceptibility to gentamicin in resistant L. monocytogenes strains.

Main Methods:

• Determined the minimum inhibitory concentration (MIC) of gentamicin alone and in combination with aqueous licorice extract against L. monocytogenes.
• Tested the efficacy of the combination therapy on gentamicin-resistant clinical isolates of L. monocytogenes.

Main Results:

• Aqueous licorice extract demonstrated significant antimicrobial synergy with gentamicin against L. monocytogenes.
• The minimum inhibitory concentration (MIC) of gentamicin was reduced by 32-fold in the presence of 1 mg/mL licorice extract.
• Licorice extract resensitized gentamicin-resistant L. monocytogenes clinical isolates to gentamicin.

Conclusions:

• Licorice extract acts as a potent adjuvant, enhancing the efficacy of gentamicin against Listeria monocytogenes.
• This combination therapy holds promise for improving the treatment of listeriosis, especially in cases involving antibiotic resistance.
• The findings support the potential use of licorice extract as a complementary agent in antimicrobial strategies for listeriosis.