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Updated: Jun 24, 2025
Antimicrobial Synergy Testing by the Inkjet Printer-assisted Automated Checkerboard Array and the Manual Time-kill Method
Published on: April 18, 2019
Amoxicillin and Ceftriaxone: A Synergistic Association Against Listeria monocytogenes
Thibault Sixt1, Florian Moretto1, Sylvia Das Neves1
1Department of Infectious Diseases, Dijon Bourgogne University Hospital, Dijon, France.
Abstract:
Among 15 strains of Listeria monocytogenes tested, a synergy between amoxicillin and ceftriaxone was observed in 14 (93%) according to minimal inhibitory concentration strips and 12 (80%) per the checkerboard methods, as well as for 2 of the 3 strains tested by the time-killing curve. This association may be an alternative treatment for listeriosis in the future.
Insights
Amoxicillin and ceftriaxone show synergy against Listeria monocytogenes, a dangerous bacterium. This combination could offer a new future treatment for listeriosis infections.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Listeria monocytogenes is a significant foodborne pathogen.
- Listeriosis, the infection caused by L. monocytogenes, can be severe, particularly in vulnerable populations.
- Effective antibiotic treatments are crucial for managing listeriosis.
Purpose of the Study:
- To investigate the synergistic effects of amoxicillin and ceftriaxone against Listeria monocytogenes.
- To evaluate the potential of this antibiotic combination as a future therapeutic strategy for listeriosis.
Main Methods:
- Minimal inhibitory concentration (MIC) strips were used to assess drug synergy.
- Checkerboard methods were employed for quantitative synergy testing.
- Time-killing curves were utilized to evaluate the bactericidal activity of the combination.
Main Results:
- Synergistic activity between amoxicillin and ceftriaxone was observed in 14 out of 15 (93%) Listeria monocytogenes strains by MIC strips.
- Checkerboard methods confirmed synergy in 12 out of 15 (80%) strains.
- Time-killing curves demonstrated synergistic effects in 2 out of 3 tested strains.
Conclusions:
- A significant synergy exists between amoxicillin and ceftriaxone against Listeria monocytogenes.
- This antibiotic combination presents a promising alternative treatment option for listeriosis.
