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Isolation and properties of metronidazole-resistant mutants of Clostridium perfringens
Abstract:
Clostridium perfringens strains resistant to metronidazole and tinidazole were isolated from the sensitive parent strain CM288 after mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine. Strain CM288 was already resistant to rifampicin and nalidixic acid; these genetic markers helped to confirm the identity of mutants. All mutants showed similar characteristics: they grew more slowly than the parent strain and failed to reach the same maximum turbidity; uptake of metronidazole and tinidazole from culture fluids was slow and end products of glucose metabolism were different from those of the parent. Pyruvate dehydrogenase activity was not detected in broken cell preparations of the mutant strains although this enzyme was readily detected in the parent strain. Changes in end products of glucose metabolism were consistent with the absence of pyruvate dehydrogenase activity because pyruvate was accumulated during growth and lactate levels were higher whereas acetate, CO2 and ethanol levels were diminished.
Insights
Researchers developed Clostridium perfringens strains resistant to metronidazole and tinidazole. These mutants exhibited slower growth and altered glucose metabolism due to absent pyruvate dehydrogenase activity, impacting antibiotic resistance studies.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Clostridium perfringens is an opportunistic pathogen.
- Antimicrobial resistance is a growing concern in bacterial infections.
- Metronidazole and tinidazole are key drugs for treating anaerobic bacterial infections.
Purpose of the Study:
- To generate and characterize Clostridium perfringens mutants resistant to metronidazole and tinidazole.
- To investigate the metabolic and growth characteristics of these resistant strains.
Main Methods:
- Bacterial mutagenesis using N-methyl-N'-nitro-N-nitrosoguanidine.
- Phenotypic characterization of resistant mutants, including growth curves and end product analysis.
- Enzyme activity assays for pyruvate dehydrogenase.
Main Results:
- Mutant strains resistant to metronidazole and tinidazole were successfully isolated.
- Mutants displayed reduced growth rates and lower maximum turbidity compared to the parent strain.
- Absence of pyruvate dehydrogenase activity in mutants correlated with altered glucose metabolism, increased lactate, and decreased acetate, CO2, and ethanol production.
Conclusions:
- Pyruvate dehydrogenase is implicated in the mechanism of metronidazole and tinidazole resistance in Clostridium perfringens.
- Altered glucose metabolism and impaired growth are consequences of this enzymatic deficiency.
- These findings provide insights into antimicrobial resistance mechanisms and potential therapeutic targets.