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Updated: Jul 6, 2026

Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance
09:00

Testing the Role of Multicopy Plasmids in the Evolution of Antibiotic Resistance

Published on: May 2, 2018

Plasmid-encoded fosfomycin resistance in bacteria isolated from the urinary tract in a multicentre survey

P Arca1, G Reguera, C Hardisson

  • 1Dpto. Biología Funcional (Area de Microbiología), Facultad de Medicina, C/ Julián Clavería s/n, Oviedo, Spain.

The Journal of Antimicrobial Chemotherapy
|October 24, 1997
PubMed

Insights

Fosfomycin resistance in urinary pathogens is mainly due to chromosomal alterations, not plasmid genes fosA or fosB. PCR is effective for tracking plasmid-mediated fosfomycin resistance in epidemiological studies.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Epidemiology

Background:

  • Fosfomycin is a crucial antibiotic for treating urinary tract infections.
  • Emerging fosfomycin resistance necessitates understanding its genetic basis.
  • Plasmid-mediated resistance genes (fosA, fosB) are potential drivers of resistance.

Purpose of the Study:

  • To investigate the prevalence and mechanisms of fosfomycin resistance in Italian urinary pathogens.
  • To screen for plasmid-borne fosA and fosB genes in resistant bacterial isolates.
  • To evaluate the utility of PCR for epidemiological surveillance of fosfomycin resistance.

Main Methods:

  • Screening of 60 fosfomycin-resistant bacterial isolates from over 7400 urinary pathogens.
  • Detection of fosA and fosB genes using PCR amplification.
  • Analysis of chromosomal mechanisms, including alterations in the GlpT transport system.

Main Results:

  • Only 5 out of 60 resistant strains harbored fosA or fosB plasmid genes.
  • The majority of fosfomycin resistance was attributed to modifications in the chromosomally encoded GlpT transport system.
  • One Morganella morganii strain exhibited an unusual alpha-glycerolphosphate incorporation, requiring further study.

Conclusions:

  • Plasmid-mediated fosfomycin resistance via fosA and fosB genes is infrequent in Italian urinary pathogens.
  • Chromosomal alterations, particularly in the GlpT system, are the primary cause of fosfomycin resistance.
  • PCR is a reliable and rapid method for epidemiological surveillance of plasmid-encoded fosfomycin resistance.

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