Risks for AMR development and transmission

Now we know how AMR arises, in this article Professor Roberto La Ragione will explain why AMR has arisen, and how it can be transferred from animal to animal, and from bacteria to bacteria.

Why has AMR emerged?

• Antibiotic use and overuse in human and animal healthcare.
• Use of antibiotics as growth promoters.
• Poor patient compliance with antibiotic treatment regimes.
• Inappropriate antibiotic dose rate or course duration.
• Antimicrobials in the environment.
• Inappropriate use of disinfectants.
• Bacterial evolutionary pressures.

If any of the following factors are incorrect it may increase the risk of AMR development: treatment plan, initial diagnosis, treatment course (too long or too short), dilution of the disinfectant or exposure time to the disinfectant.

AMR can be transmitted from animal to animal or from bacteria to bacteria.

Animal to animal:

Direct contact with infected animals, contact with infected surfaces, wildlife/rodents, water, feed, bedding and people are all methods of transmission between animals. The images below show potential infection hot spots (red areas) and infection control measures to reduce infection spread (green areas). Understanding infection risks and transfer ‘hot spots’ is crucial to reducing the emergence and spread of AMR. Click to enlarge Click to enlarge Click to enlarge

Acknowledgments for images – AMRSim: A Microbial Reality Simulator. The Glasgow School of Art, University of Surrey and Fitzpatrick Referrals. Funded by an Arts and Humanities Research Council Antimicrobial Resistance (AMR) grant number AH/R002088/1

Bacteria to bacteria:

There are 3 methods of transmission of AMR from bacteria to bacteria: transformation, conjugation and transduction. Transformation involves the uptake of free DNA in the environment. The free DNA usually comes from the breakdown of dead bacteria. Conjugation is the transfer of plasmids (circular pieces of DNA), containing resistance genes, from one bacteria to another. Transduction is where bacterial DNA is transferred via bacteriophages (viruses that can only affect bacteria), to other bacteria.