Skip to main content

Targeting Efflux Pumps to Combat Antimicrobial Resistance

Principal Supervisor: Dr Jessica Blair - Institute of Microbiology and Infection

Co-supervisor: Dr Luke Alderwick

PhD project title: Targeting Efflux Pumps to Combat Antimicrobial Resistance

University of Registration: University of Birmingham

Project outline:

Antibiotic resistance is a current global health crisis. Antibiotic resistant infections kill 700,000 people worldwide every year and this number is rising annually. Bacteria become resistant to antibiotics in many ways but one important mechanism is via multi-drug efflux pumps (Blair et al., 2015; Blair, Richmond et al. 2014). These are pumps that are found in the bacterial cell membrane and can pump antibiotics out of bacterial cells. This reduces the amount of drug inside the bacterial cell allowing them to survive at higher drug concentrations and therefore, conferring antibiotic resistance. Many efflux pumps can export multiple classes of antibiotic so the bacteria are resistant to many drugs at the same time, known as multi-drug resistant (MDR).

The Resistance Nodulation Division (RND) family of efflux pumps confer antibiotic resistance to many human and animal pathogens, including the foodborne pathogen Salmonella. In Salmonella the major efflux pump of this family, AcrB, confers antibiotic resistance and is commonly over-expressed in multi-drug resistant (MDR) clinical and veterinary isolates. RND pumps, such as AcrB, work with two other protein components to form a tri-partite pump system. One of the essential components of the tripartite efflux pump is called the Periplasmic Adaptor Protein (PAP) and we have previously shown that the PAPs are a good target against which inhibitor molecules could be developed (Blair et al., 2009; Smith and Blair, 2014). If an appropriate inhibitor was identified it could be prescribed alongside an already licensed antibiotic to confer susceptibility to that drug and to prevent resistance to that antibiotic from occurring. Efflux pumps such as AcrB are also required for many Gram-negative pathogens to form biofilms and to cause infection therefore, a successful inhibitor would not only reduce resistance to antimicrobials, but could also be used as an anti-virulence and anti-biofilm agent or to prevent colonisation of animals within the food chain.

The main research focus of Dr Blair’s lab is developing inhibitors of the periplasmic adaptor protein. This currently includes validation of the PAPs as a target for efflux pump inhibitors, understanding the biological effect on the bacterial cell of losing PAP function and investigating the likelihood of resistance to PAP inhibition occurring. Future directions include studying the structure/function of all the PAPs and/or development of, and screening for, inhibitor molecules. The project will require a combination of molecular microbiology, bacterial physiology, structural biology and high-throughput drug screening.

References:

  1. Blair, J. M., G. E. Richmond and L. J. Piddock (2014). "Multidrug efflux pumps in Gram-negative bacteria and their role in antibiotic resistance." Future Microbiol 9(10): 1165-1177.
  2. Jessica M A Blair, Roberto M La Ragione, Martin J Woodward and Laura J V Piddock. The Periplasmic Adaptor Protein AcrA has a Distinct role in Antibiotic Resistance and Virulence of Salmonella enterica Serovar Typhimurium. Journal of Antimicrobial Chemotherapy, 64(5): 956-72 Nov 2009.
  3. Helen E Smith and Jessica M A Blair. Redundancy in the periplasmic adaptor proteins AcrA and AcrE provides resilience and an ability to export substrates of multidrug efflux. Journal of Antimicrobial Chemotherapy. 2014. 69(4): 982-987.
  4. Blair, J. M., M. A. Webber, A. J. Baylay, D. O. Ogbolu and L. J. Piddock (2015). "Molecular mechanisms of antibiotic resistance." Nat Rev Microbiol 13(1): 42-51.

BBSRC Strategic Research Priority: Food Security

Techniques that will be undertaken during the project:

The techniques used during this project will include:

  • Basic microbiology (including measuring antimicrobial susceptibility, mutant selection etc)
  • Molecular microbiology (including PCR, sequencing, cloning etc)
  • Measurement of bacterial efflux using a range of assays
  • Flow cytometry
  • Development of High-throughput drug screening including development of miniaturised cellular screening assays, use of Microtitre plate readers (absorbance/fluorescence/luminescence), operation of automated liquid handling robotics and data analysis (chemoinformatics) of large biological data sets reconciled with chemical information. (With Dr Luke Alderwick)

Contact: Dr Jessica Blair, University of Birmingham