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Antimicrobial susceptibility of Enterococcus strains used in clinical practice as probiotics
Tetsuo Yamaguchi1, Yuri Miura, Tetsuya Matsumoto
1Department of Microbiology, Tokyo Medical University, 6-1-1, Shinjuku, Shinjuku-ku, Tokyo, 160-8402, Japan.
Abstract:
The aim of this study was to evaluate the antimicrobial susceptibilities of probiotic strains that are suggested to be effective for preventing antibiotics-associated diarrhea (AAD). The minimum inhibitory concentrations (MICs) of 17 antibiotics against probiotic strains were tested by the agar plate dilution method or broth microdilution method. In all, eight probiotic strains containing Enterococcus faecalis, Bifidobacterium spp., Clostridium butyricum, and Lactobacillus acidophilus were tested. Although the MIC range was wide, from less than 0.0625 to more than 1,024 μg/ml, the MICs of 11 beta-lactams were high for three of four enterococci, with a range of 32 to more than 1,024 μg/ml. In contrast, fluoroquinolones and vancomycin showed potent activities against all enterococci, of which MICs were 0.25-8 μg/ml. Two Bifidobacterium strains and one Lactobacillus strain showed low MICs against many of the beta-lactams, fluoroquinolones, macrolides, and vancomycin, with MICs of 8 μg/ml or less. Fosfomycin showed generally mild activity against enterococci (MIC, 8-32 μg/ml) and anaerobic strains (MIC, 32 to >1,024 μg/ml), respectively. The probiotics strains with high MIC values may survive in the intestinal tract, even if the patient was concomitantly using the antibiotics in clinical practice. Therefore, our results suggest that adequate combinations of probiotics strains and antibiotics should be important for preventing AAD. Further study is needed to determine the efficacy of probiotics in clinical practice.
Insights
This study assessed antibiotic resistance in probiotics for preventing antibiotic-associated diarrhea (AAD). Some probiotics showed resistance to certain antibiotics, highlighting the need for careful selection to ensure effectiveness.
Area of Science:
- Microbiology
- Pharmacology
- Gastroenterology
Background:
- Antibiotic-associated diarrhea (AAD) is a common side effect of antibiotic therapy.
- Probiotics are often recommended to prevent AAD, but their efficacy can be influenced by antibiotic resistance.
- Understanding the antimicrobial susceptibility of probiotic strains is crucial for their effective use.
Purpose of the Study:
- To evaluate the antimicrobial susceptibilities of specific probiotic strains.
- To determine the Minimum Inhibitory Concentrations (MICs) of various antibiotics against these probiotics.
- To inform the selection of probiotic-antibiotic combinations for preventing AAD.
Main Methods:
- Tested eight probiotic strains including Enterococcus faecalis, Bifidobacterium spp., Clostridium butyricum, and Lactobacillus acidophilus.
- Utilized agar plate dilution and broth microdilution methods to determine MICs.
- Evaluated the activity of 17 different antibiotics against the selected probiotic strains.
Main Results:
- Probiotic strains exhibited a wide range of MICs (0.0625 to >1,024 μg/ml) against 17 antibiotics.
- Enterococci showed high resistance to beta-lactams but were susceptible to fluoroquinolones and vancomycin.
- Bifidobacterium and Lactobacillus strains displayed low MICs against beta-lactams, fluoroquinolones, macrolides, and vancomycin.
Conclusions:
- Probiotic strains with high MIC values may survive concurrent antibiotic treatment, potentially aiding in AAD prevention.
- Careful selection of probiotic strains and antibiotic combinations is essential for managing AAD.
- Further clinical studies are required to confirm the practical efficacy of these probiotics in preventing AAD.
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