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Published on: March 16, 2012

Transfer of a plasmid-specified beta-lactamase gene from Haemophilus influenzae

J R Saunders, R B Sykes

    Antimicrobial Agents and Chemotherapy
    |February 1, 1977
    PubMed

    Insights

    Ampicillin resistance genes transferred between bacteria like Haemophilus influenzae and E. coli. The gene transfer, likely via conjugation, often resulted in stable chromosomal insertion, especially in Pseudomonas aeruginosa.

    Area of Science:

    • Microbiology
    • Genetics
    • Molecular Biology

    Background:

    • Ampicillin resistance in bacteria poses a significant public health challenge.
    • Understanding the mechanisms of resistance gene transfer is crucial for combating antibiotic resistance.

    Purpose of the Study:

    • To investigate the transfer of ampicillin resistance genes from Haemophilus influenzae to other bacterial species.
    • To elucidate the mechanism and stability of resistance gene transfer and integration.

    Main Methods:

    • Conjugation experiments were performed using ampicillin-resistant Haemophilus influenzae as donors.
    • Recipient strains included Haemophilus parainfluenzae, Escherichia coli, and Pseudomonas aeruginosa.
    • Characterization of extrachromosomal DNA and analysis of gene integration into host chromosomes were conducted.

    Main Results:

    • Haemophilus influenzae strains transferred ampicillin resistance genes encoding TEM beta-lactamase to recipient bacteria.
    • Transfer occurred via conjugation, even without detectable plasmids, and resistance was often unstable.
    • Stable transcipients showed chromosomal insertion of the beta-lactamase gene, sometimes associated with auxotrophy induction in P. aeruginosa and E. coli.

    Conclusions:

    • Bacterial conjugation can facilitate the transfer of ampicillin resistance genes, even in the absence of plasmids.
    • Chromosomal insertion provides a mechanism for stable inheritance of resistance genes.
    • The lack of a penetration barrier to beta-lactam drugs in Haemophilus may explain delayed resistance acquisition.

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