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Interspecies gene transfer in vivo producing an outbreak of multiply resistant shigellosis

R V Tauxe1, T R Cavanagh, M L Cohen

  • 1Division of Bacterial Diseases, Centers for Disease Control, Atlanta, Georgia 30333.

The Journal of Infectious Diseases
|December 1, 1989
PubMed

Insights

A diabetic patient on trimethoprim/sulfamethoxazole (TMP/SMZ) therapy likely spread a multiply-drug-resistant Shigella flexneri strain. This strain acquired its resistance plasmid from an Escherichia coli strain also present in the patient.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Antimicrobial Resistance

Background:

  • An outbreak of multiply-drug-resistant Shigella flexneri 3a occurred on the Hopi Indian reservation in 1983.
  • The index patient had a concurrent Escherichia coli urinary tract infection and shigellosis.

Observation:

  • Both E. coli and S. flexneri isolates from the index patient exhibited resistance to multiple antibiotics.
  • A transferable 35-MDa plasmid was identified in both E. coli and S. flexneri isolates.
  • An E. coli strain isolated from the patient weeks prior showed identical antimicrobial resistance patterns.

Findings:

  • The E. coli and S. flexneri isolates shared a common 35-MDa plasmid conferring multiple drug resistance.
  • The plasmid was transferable to recipient E. coli strains.
  • The index patient's prior E. coli infection possessed the same resistance plasmid.

Implications:

  • The index patient, undergoing prophylactic trimethoprim/sulfamethoxazole (TMP/SMZ) therapy, was identified as the probable source of the R-plasmid for the outbreak strain.
  • This highlights the potential for antimicrobial resistance plasmids to transfer between different bacterial species in a single host.
  • Understanding plasmid-mediated resistance is crucial for controlling infectious disease outbreaks.

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