Reduction trend of mcr-1 circulation in Emilia-Romagna Region, Italy

Carlo Gagliotti, Luca Bolzoni, Edoardo Carretto, Mario Sarti, Enrico Ricchizzi, Simone Ambretti, Agostino Barozzi, Chiara Bracchi, Massimo Confalonieri, Ilaria Menozzi, Marina Morganti, Maria Federica Pedna, Vittorio Sambri, Erika Scaltriti, Roberta Schiavo, Laura Soliani, Martina Tambassi, Claudia Venturelli, Carlo Biagetti, Rossella ButtazziAdriana Calderaro, Chiara Casadio, Marianna Meschiari, Fabio Tumietto, Giuseppe Diegoli, Stefano Pongolini, Maria Luisa Moro

Research output: Contribution to journalArticlepeer-review


This study aims to describe trends of mcr-positive Enterobacterales in humans based on laboratory surveillance with a defined catchment population. The data source is the Micro-RER surveillance system, established in Emilia-Romagna region (Italy), to monitor the trend of mcr resistance. Enterobacterales isolates from human clinical samples with minimum inhibitory concentration (MIC) ≥ 2 mg/L for colistin were sent to the study reference laboratory for the detection of mcr genes. Isolates prospectively collected in the period 2018–2020 were considered for the assessment of population rates and trends; further analyses were carried out for the evaluation of clonality and horizontal mcr gene transfer. Previous isolates from local laboratory collection were also described. In the period 2018–2020, 1164 isolates were sent to the reference laboratory, and 51 (4.4%) were confirmed as mcr-positive: 50 mcr-1 (42 Escherichia coli, 6 Klebsiella pneumoniae, 2 Salmonella enterica) and 1 mcr-4 (Enterobacter cloacae). The number of mcr-positive isolates dropped from 24 in the first half of 2018 to 3 in the whole of 2020 (trend p value < 0.001). Genomic analyses showed the predominant role of the horizontal transfer of mcr genes through plasmids or dissemination of transposable elements compared to clonal dissemination of mcr-positive microorganisms. The study results demonstrate a substantial decrease in the circulation of mcr-1 plasmid genes in Emilia-Romagna Region.

Original languageEnglish
Pages (from-to)2585-2592
Number of pages8
JournalEuropean Journal of Clinical Microbiology and Infectious Diseases
Issue number12
Publication statusPublished - Dec 2021


  • Antibiotic resistance
  • Antimicrobials for veterinary use
  • Clonal dissemination
  • Colistin
  • Enterobacterales
  • Horizontal transfer
  • Humans
  • Mcr
  • One Health approach

ASJC Scopus subject areas

  • Microbiology (medical)
  • Infectious Diseases


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