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Published on: May 2, 2018

Trimethoprim-resistant bacteria: cross-resistance patterns

D Grey, J M Hamilton-Miller

    Microbios
    |January 1, 1977
    PubMed

    Insights

    Trimethoprim-resistant bacteria showed cross-resistance to pyrimethamine and methasquin. Proguanil exhibited consistent activity, suggesting it may not be an anti-folate agent.

    Area of Science:

    • Microbiology
    • Pharmacology
    • Antimicrobial Resistance

    Background:

    • Trimethoprim is a widely used antibiotic.
    • Emerging resistance to trimethoprim necessitates the investigation of alternative antimicrobial agents.
    • Understanding cross-resistance patterns is crucial for effective treatment strategies.

    Purpose of the Study:

    • To evaluate the sensitivity of trimethoprim-resistant bacteria to other dihydrofolate reductase inhibitors.
    • To determine the antibacterial activity spectrum of proguanil, pyrimethamine, methotrexate, and methasquin against resistant strains.
    • To investigate potential cross-resistance between trimethoprim and these agents.

    Main Methods:

    • Testing 181 clinically isolated trimethoprim-resistant bacterial strains.
    • Assessing bacterial sensitivity to proguanil, pyrimethamine, methotrexate, and methasquin.
    • Comparing the intrinsic antibacterial activity of tested agents with trimethoprim.

    Main Results:

    • All tested agents demonstrated lower intrinsic antibacterial activity than trimethoprim.
    • Significant cross-resistance was observed between trimethoprim and pyrimethamine/methasquin.
    • Methotrexate showed minimal activity against Gram-negative bacilli but was inhibitory to streptococci.
    • Proguanil displayed consistent activity across all tested organisms and may not function as an anti-folate agent.

    Conclusions:

    • Trimethoprim resistance is associated with cross-resistance to pyrimethamine and methasquin.
    • Proguanil's consistent activity suggests a different mechanism of action, distinct from folate antagonism.
    • Further research into proguanil's efficacy and mechanism is warranted for clinical applications.

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