Cefotaxime exposure selects mutations within the CA-domain of envZ which promote antibiotic resistance but repress biofilm formation in Salmonella

Trampari, Eleftheria, Zhang, Chuanzhen, Gotts, Kathryn, Savva, George M., Bavro, Vassiliy N. and Webber, Mark (2022) Cefotaxime exposure selects mutations within the CA-domain of envZ which promote antibiotic resistance but repress biofilm formation in Salmonella. Microbiology Spectrum, 10 (3). ISSN 2165-0497

Preview

PDF (trampari-et-al-2022-cefotaxime-exposure-selects-mutations-within-the-ca-domain-of-envz-which-promote-antibiotic) - Published Version Available under License Creative Commons Attribution. Download (2MB) | Preview

Abstract

Cephalosporins are important beta lactam antibiotics, but resistance can be mediated by various mechanisms including production of beta lactamase enzymes, changes in membrane permeability or active efflux. We used an evolution model to study how Salmonella adapts to subinhibitory concentrations of cefotaxime in planktonic and biofilm conditions and characterized the mechanisms underpinning this adaptation. We found that Salmonella rapidly adapts to subinhibitory concentrations of cefotaxime via selection of multiple mutations within the CA-domain region of EnvZ. We showed that changes in this domain affect the ATPase activity of the enzyme and in turn impact OmpC, OmpF porin expression and hence membrane permeability leading to increased tolerance to cefotaxime and low-level resistance to different classes of antibiotics. Adaptation to cefotaxime through EnvZ also resulted in a significant cost to biofilm formation due to downregulation of curli. We assessed the role of the mutations identified on the activity of EnvZ by genetic characterization, biochemistry and in silico analysis and confirmed that they are responsible for the observed phenotypes. We observed that sublethal cefotaxime exposure selected for heterogeneity in populations with only a subpopulation carrying mutations within EnvZ and being resistant to cefotaxime. Population structure and composition dynamically changed depending on the presence of the selection pressure, once selected, resistant subpopulations were maintained even in extended passage without drug. IMPORTANCE Understanding mechanisms of antibiotic resistance is crucial to guide how best to use antibiotics to minimize emergence of resistance. We used a laboratory evolution system to study how Salmonella responds to cefotaxime in both planktonic and biofilm conditions. In both contexts, we observed rapid selection of mutants within a single hot spot within envZ. The mutations selected altered EnvZ which in turn triggers changes in porin production at the outer membrane. Emergence of mutations within this region was repeatedly observed in parallel lineages in different conditions. We used a combination of genetics, biochemistry, phenotyping and structural analysis to understand the mechanisms. This data show that the changes we observe provide resistance to cefotaxime but come at a cost to biofilm formation and the fitness of mutants changes greatly depending on the presence or absence of a selective drug. Studying how resistance emerges can inform selective outcomes in the real world.

Item Type:	Article
Additional Information:	Funding Information: E.T. and M.W. were supported by the BBSRC Institute Strategic Program Microbes in the Food Chain BB/R012504/1 and its constituent project BBS/E/F/000PR10349. G.M.S. were supported by the Quadram Institute Bioscience BBSRC funded Core Capability Grant (project number BB/CCG1860/1). Bioinformatics analyses were performed on CLIMB-computing servers, an infrastructure supported by a grant from the UK Medical Research Council (MR/L015080/1).
Uncontrolled Keywords:	antimicrobial resistance,biofilms,evolution,two component systems,physiology,ecology,immunology and microbiology(all),genetics,microbiology (medical),cell biology,infectious diseases,sdg 3 - good health and well-being ,/dk/atira/pure/subjectarea/asjc/1300/1314
Faculty \ School:	Faculty of Medicine and Health Sciences > School of Health Sciences Faculty of Medicine and Health Sciences > Norwich Medical School
UEA Research Groups:	Faculty of Science > Research Groups > Norwich Epidemiology Centre Faculty of Medicine and Health Sciences > Research Groups > Norwich Epidemiology Centre
Related URLs:	http://www.scopus.com/inward/record.url?...
Depositing User:	LivePure Connector
Date Deposited:	31 Oct 2024 09:30
Last Modified:	15 Dec 2024 01:28
URI:	https://ueaeprints.uea.ac.uk/id/eprint/97356
DOI:	10.1128/spectrum.02145-21

Downloads

Actions (login required)

View Item