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Inactivation of penicillin G during experimental infection with Bacteroides fragilis
Abstract:
An animal model implanted with intraperitoneal plastic reservoirs was used for study of the penetration of penicillin G into sites infected with Bacteroides fragilis. Penicillin G was given to rabbits, and its concentration in uninfected reservoirs and in those infected with B. fragilis was determined. The mean percentage penetration ([concentration in capsule divided by peak concentration in serum] X 100) of penicillin into uninfected capsules was 19.9%, whereas that into heavily infected capsules was 1.5%. The percentage penetration of radiolabeled penicillin into infected capsules was 12.5%, whereas the proportion of bioactive drug in the same capsules was again very low (1%). These results show that there is a modest reduction in penetration of penicillin into infected sites and a striking inactivation of the drug by B. fragilis in this experimental model.
Insights
Penicillin G penetration into infection sites was reduced, and Bacteroides fragilis bacteria inactivated the drug. This animal model study highlights challenges in treating B. fragilis infections with penicillin G.
Area of Science:
- Pharmacology
- Microbiology
- Infectious Diseases
Background:
- Bacteroides fragilis is a common cause of serious infections.
- Penicillin G is a widely used antibiotic, but its efficacy against B. fragilis can be variable.
Purpose of the Study:
- To investigate the penetration of penicillin G into sites infected with B. fragilis.
- To determine the impact of B. fragilis infection on penicillin G concentrations in infected tissues.
Main Methods:
- An animal model using rabbits with intraperitoneal plastic reservoirs was established.
- Penicillin G concentrations were measured in infected and uninfected reservoirs.
- Radiolabeled penicillin G was used to assess drug penetration and bioactivity.
Main Results:
- Penicillin G penetration into uninfected capsules was 19.9%, significantly reduced to 1.5% in heavily infected capsules.
- Radiolabeled penicillin G showed 12.5% penetration into infected capsules, but only 1% remained bioactive.
- A modest reduction in penetration and striking inactivation by B. fragilis were observed.
Conclusions:
- Bacteroides fragilis significantly reduces penicillin G penetration and bioactivity in infected tissues.
- The findings suggest limitations in using penicillin G for B. fragilis infections due to drug inactivation.
- Further research into alternative treatment strategies for B. fragilis infections is warranted.