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Amoxycillin-resistant oral streptococci and experimental infective endocarditis in the rabbit
L P Longman1, P D Marsh, M V Martin
1Department of Clinical Dental Sciences, University of Liverpool, UK.
Abstract:
The ability of three amoxycillin-resistant strains of Streptococcus sanguis 254, 24 and 297 (MIC 40 mg/L) to cause infective endocarditis (IE) in the rabbit was investigated. These strains all produced infection in the rabbit, as did an antibiotic sensitive control strain NCTC 7864. Prophylactic amoxycillin (400 mg/kg body weight) administered one hour before bacterial challenge prevented 80% of the animals developing IE irrespective of the challenging strain. It is concluded that amoxycillin-resistant strains of S. sanguis can cause IE and that amoxycillin prophylaxis can still be effective against these bacteria.
Insights
Amoxycillin-resistant Streptococcus sanguis strains can cause infective endocarditis (IE) in rabbits. However, prophylactic amoxycillin treatment remains effective in preventing IE, even with resistant bacterial strains.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Infective endocarditis (IE) is a serious infection, often caused by bacteria like Streptococcus sanguis.
- The emergence of antibiotic resistance in bacterial pathogens poses a significant challenge to treatment and prevention strategies.
- Amoxycillin is a commonly used antibiotic for IE prophylaxis and treatment.
Purpose of the Study:
- To investigate the capacity of amoxycillin-resistant Streptococcus sanguis strains to induce infective endocarditis (IE) in a rabbit model.
- To evaluate the efficacy of prophylactic amoxycillin administration against IE caused by amoxycillin-resistant S. sanguis.
Main Methods:
- Three amoxycillin-resistant strains of Streptococcus sanguis (MIC 40 mg/L) and one sensitive strain were used.
- Infection was induced in a rabbit model by bacterial challenge.
- Prophylactic amoxycillin (400 mg/kg body weight) was administered one hour before bacterial challenge.
Main Results:
- All tested Streptococcus sanguis strains, including amoxycillin-resistant ones, successfully caused infective endocarditis in the rabbit model.
- Prophylactic amoxycillin administration prevented IE in 80% of the animals, regardless of the challenging strain's resistance profile.
Conclusions:
- Amoxycillin-resistant strains of Streptococcus sanguis are capable of causing infective endocarditis.
- Amoxycillin prophylaxis demonstrates continued efficacy against amoxycillin-resistant Streptococcus sanguis strains in preventing IE.