Related Experiment Videos
The effect of some antibiotics on Enterococcus faecium SF 68 inoculated in germ-free mice
L D Trovatelli1, P G Sarra, S Massa
1Dipartimento di Agrobiologia e Agrochimica, Università della Tuscia, Viterbo, Italy.
Abstract:
A strain of Enterococcus faecium SF 68 (sensitive to penicillin, tetracycline, virginiamicin and tylosin, but resistant to streptomycin) was administered to five groups of germ-free mice. Each group was subsequently given 40 micrograms/ml and then 80 micrograms/ml of a single antibiotic. The following determinations were made: a) colonization of the bacterial strain before and after administration of the antibiotic and b) the MICs in the original strain and after administration of the antibiotic (80 micrograms Iml). The results show that in the mice treated with streptomycin, colonization is not influenced by the antibiotic treatment; in mice treated with antibiotics to which the strain is sensitive, the colonization increases in proportion to the level of the antibiotic resistance (tylosin and tetracycline).
Insights
Antibiotic resistance in Enterococcus faecium SF 68 was studied in germ-free mice. Treatment with sensitive antibiotics increased bacterial colonization, while streptomycin had no effect, highlighting complex interactions between antibiotics and gut bacteria.
Area of Science:
- Microbiology
- Pharmacology
- Germ-free animal models
Background:
- Enterococcus faecium SF 68 is a bacterial strain with a defined antibiotic resistance profile.
- Understanding how antibiotics affect bacterial colonization is crucial for managing infections and antibiotic resistance.
- Germ-free mice provide a controlled environment to study host-microbe-drug interactions.
Purpose of the Study:
- To investigate the impact of different antibiotics on the colonization of Enterococcus faecium SF 68 in germ-free mice.
- To determine if antibiotic administration influences the minimum inhibitory concentrations (MICs) of the bacteria.
- To correlate antibiotic resistance levels with colonization changes.
Main Methods:
- Administration of Enterococcus faecium SF 68 to five groups of germ-free mice.
- Treatment of each group with specific antibiotics (penicillin, tetracycline, virginiamicin, tylosin, streptomycin) at increasing concentrations (40 µg/ml, then 80 µg/ml).
- Monitoring bacterial colonization before and after antibiotic treatment and determining MICs of the original strain and post-treatment isolates.
Main Results:
- Streptomycin treatment did not affect Enterococcus faecium SF 68 colonization.
- Antibiotics to which the strain was sensitive (tylosin, tetracycline) led to increased bacterial colonization.
- The increase in colonization correlated with the level of antibiotic resistance, suggesting a complex adaptive response.
Conclusions:
- Antibiotic treatment can paradoxically increase the colonization of susceptible bacterial strains.
- The effect of antibiotics on bacterial colonization is dependent on the specific antibiotic and the bacterial resistance profile.
- Further research is needed to elucidate the mechanisms underlying antibiotic-induced increases in bacterial load.