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In-vitro antibiotic inactivation by mammalian cell and killed bacterial preparations
Abstract:
Inactivation of a range of antibiotics acting at different points in the metabolism of the bacterial cell was detected by estimating the MIC and MBC in the presence of liver and other tissue preparations. High temperature treatment and sonication of liver cells increased their ability to inactivate antibiotic action. This treatment would have almost completely destroyed enzyme activity, which was, therefore, not thought likely to be the cause of the phenomenon. The loss of antibiotic activity may be related to "protein binding" and a dialysis experiment showed that penicillin binding with liver homogenate was very much greater than with human albumin. It may be that increased disruption of tissue cells by physical methods exposes more active binding sites which reduces the bioavailability of antibiotics. Some degree of binding specificity was indicated in experiments in which DNA was shown to block antibiotics acting primarily on DNA--related synthesis and RNA blocked antibiotics acting on RNA--related metabolism. Suggestions are made for the cause of failure of antibiotic treatment in certain clinical situations.
Insights
Tissue preparations significantly inactivate antibiotics, potentially through protein binding rather than enzymes. This binding may explain antibiotic treatment failures in certain clinical scenarios.
Area of Science:
- Microbiology
- Pharmacology
- Biochemistry
Background:
- Antibiotic efficacy is crucial for treating bacterial infections.
- Understanding factors affecting antibiotic activity in vivo is essential.
- Tissue interactions can influence drug bioavailability and effectiveness.
Purpose of the Study:
- To investigate the inactivation of various antibiotics by tissue preparations.
- To explore the mechanisms behind antibiotic inactivation.
- To identify potential causes for antibiotic treatment failure.
Main Methods:
- Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays were performed.
- Antibiotic activity was tested in the presence of liver and other tissue preparations.
- Tissue cells were treated with high temperature and sonication to assess their impact on inactivation.
- Dialysis experiments were conducted to evaluate antibiotic binding to tissue homogenates and albumin.
- Experiments involving DNA and RNA were used to assess binding specificity.
Main Results:
- Liver and tissue preparations demonstrated significant antibiotic inactivation.
- Heat and sonication treatments enhanced the inactivating capacity of liver cells, suggesting a non-enzymatic mechanism.
- Penicillin exhibited much greater binding to liver homogenate than to human albumin, indicating strong protein binding.
- Binding specificity was observed, with DNA and RNA blocking antibiotics targeting related metabolic pathways.
- Increased disruption of tissue cells appeared to expose more binding sites, reducing antibiotic bioavailability.
Conclusions:
- Tissue interactions, particularly protein binding, play a significant role in antibiotic inactivation.
- The observed binding phenomenon may contribute to the failure of antibiotic treatments in specific clinical situations.
- Further research into tissue-drug interactions is warranted to optimize antibiotic therapy.