Acquisition and Spread of Antimicrobial Resistance: A tet(X) Case Study

Rustam Aminov* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)
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Understanding the mechanisms leading to the rise and dissemination of antimicrobial resistance (AMR) is crucially important for the preservation of power of antimicrobials and controlling infectious diseases. Measures to monitor and detect AMR, however, have been significantly delayed and introduced much later after the beginning of industrial production and consumption of antimicrobials. However, monitoring and detection of AMR is largely focused on bacterial pathogens, thus missing multiple key events which take place before the emergence and spread of AMR among the pathogens. In this regard, careful analysis of AMR development towards recently introduced antimicrobials may serve as a valuable example for the better understanding of mechanisms driving AMR evolution. Here, the example of evolution of (X), which confers resistance to the next-generation tetracyclines, is summarised and discussed. Initial mechanisms of resistance to these antimicrobials among pathogens were mostly via chromosomal mutations leading to the overexpression of efflux pumps. High-level resistance was achieved only after the acquisition of flavin-dependent monooxygenase-encoding genes from the environmental microbiota. These genes confer resistance to all tetracyclines, including the next-generation tetracyclines, and thus were termed (X). IS and IS as well as a variety of conjugative and mobilizable plasmids of different incompatibility groups, played an essential role in the acquisition of (X) genes from natural reservoirs and in further dissemination among bacterial commensals and pathogens. This process, which took place within the last decade, demonstrates how rapidly AMR evolution may progress, taking away some drugs of last resort from our arsenal.
Original languageEnglish
Article number3905
Number of pages14
JournalInternational Journal of Molecular Sciences
Issue number8
Early online date9 Apr 2021
Publication statusE-pub ahead of print - 9 Apr 2021


  • antimicrobial resistance
  • horizontal gene transfer
  • mobile genetic elements
  • natural reservoirs
  • next-generation tetracyclines
  • tetracyclines


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