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Tackling AMR in wastewater systems with sneaky bacteria

Wastewater treatment plants (WWTPs) reduce levels of antimicrobial resistance (AMR) genes and bacteria. But occasionally, they also select for multidrug resistance bacteria.

Project leader

Prof David Graham

Prof Jeff Errington



Project staff

Dr Kelly Jobling

Mr Adrian Blackburn


Northumbrian Water Ltd


Chinese National Academy of Science - Xiamen


Multidrug resistant bacteria contain genetically mobile elements.

This is partly because of how we separate biosolids WWTPs. But it may also be due to novel intrinsic traits of some bacteria who can resist antimicrobials under any conditions. For example, some bacteria can switch to a reversible, cell-wall deficient state called the L-form. This results in broad resistance to any antimicrobials that can act on cell wall synthesis pathways. Thus, L-form cells are multidrug resistant (MDR).

L-form bacteria often look like bubbles when they develop this unusual state. The picture is of a highly resistant E. coli as an L-form. This E. coli is normally a short rod and 1000 times more susceptible than this strain.

We are isolating and identifying L-form bacteria from wastewater systems. We are investigating the role these bacteria play in the selection of AMR, in particular multidrug resistance in WWTPs.

We are also assessing more ecological explanations for elevated MDR strains, including selective predation.