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Colonization resistance of the digestive tract of mice during systemic antibiotic treatment
Abstract:
During systemic treatment of mice with ampicillin or streptomycin, oral contaminations with exogenous bacterial species resulted in an abnormal colonization pattern. The contaminants persisted much longer and in much higher concentrations in the caecum of systemically treated mice than in control animals. Spread of the contaminant into the mesenteric lymph nodes and the spleen was found much more often in the antibiotic treated group. This, however, was only seen when the contaminant was ;resistant' to the antibiotic injected. The experiments suggest that the ;CR-inducing species' of the microflora live in close contact with the mucosa and therefore could be identical with the anaerobic tapered rods described by Savage & Dubos (1968).
Insights
Antibiotics like ampicillin disrupt normal gut bacteria, allowing oral contaminants to colonize and spread. Resistant bacteria showed increased persistence and systemic spread in antibiotic-treated mice.
Area of Science:
- Microbiology
- Immunology
- Pharmacology
Background:
- Systemic antibiotic administration can alter the gut microbiome.
- The impact of antibiotics on the colonization resistance of the gut microbiota is not fully understood.
Purpose of the Study:
- To investigate the effect of systemic ampicillin and streptomycin treatment on the colonization pattern of orally introduced bacterial contaminants in mice.
- To determine if antibiotic resistance influences the persistence and spread of contaminants.
Main Methods:
- Mice were treated systemically with ampicillin or streptomycin.
- Oral gavage with exogenous bacterial species was performed.
- Colonization patterns in the caecum, mesenteric lymph nodes, and spleen were analyzed.
- Bacterial resistance to the administered antibiotics was assessed.
Main Results:
- Systemic antibiotic treatment led to abnormal colonization patterns of exogenous bacteria.
- Contaminants persisted longer and in higher concentrations in the caecum of treated mice.
- Spread to mesenteric lymph nodes and spleen occurred more frequently in antibiotic-treated mice, particularly with resistant contaminants.
Conclusions:
- Systemic antibiotics disrupt colonization resistance, facilitating the persistence and spread of exogenous bacteria.
- Antibiotic resistance is a critical factor in the enhanced susceptibility to contamination.
- The study suggests that mucosa-associated bacteria, potentially anaerobic tapered rods, play a role in colonization resistance.