Functional mgrA Influences Genetic Changes within a Staphylococcus aureus Cell Population over Time
Por:
Lee J, Carda-Diéguez M, Žiemyte M, Vreugde S, Cooksley C, Crosby HA, Horswill AR, Mira A, Zilm PS and Kidd SP
Publicada:
18 oct 2022
Ahead of Print:
1 sep 2022
Resumen:
Prolonged survival in the host-bacteria microenvironment drives the selection of alternative cell types in Staphylococcus aureus, permitting quasi-dormant sub-populations to develop. These facilitate antibiotic tolerance, long-term growth, and relapse of infection. Small Colony Variants (SCV) are an important cell type associated with persistent infection but are difficult to study in vitro due to the instability of the phenotype and reversion to the normal cell type. We have previously reported that under conditions of growth in continuous culture over a prolonged culture time, SCVs dominated a heterogenous population of cell types and these SCVs harbored a mutation in the DNA binding domain of the gene for the transcription factor, mgrA. To investigate this specific cell type further, S. aureus WCH-SK2-Delta mgrA itself was assessed with continuous culture. Compared to the wild type, the mgrA mutant strain required fewer generations to select for SCVs. There was an increased rate of mutagenesis within the Delta mgrA strain compared to the wild type, which we postulate is the mechanism explaining the increased emergence of SCV selection. The mgrA derived SCVs had impeded metabolism, altered MIC to specific antibiotics and an increased biofilm formation compared to non-SCV strain. Whole genomic sequencing detected single nucleotide polymorphisms (SNP) in phosphoglucosamine mutase glmM and tyrosine recombinase xerC. In addition, several genomic rearrangements were detected which affected genes involved in important functions such as antibiotic and toxic metal resistance and pathogenicity. Thus, we propose a direct link between mgrA and the SCV phenotype.
IMPORTANCE Within a bacterial population, a stochastically generated heterogeneity of phenotypes allows continual survival against current and future stressors. The generation of a sub-population of quasi-dormant Small Colony Variants (SCV) in Staphylococcus aureus is such a mechanism, allowing for persistent or relapse of infection despite initial intervention seemingly clearing the infection. The use of continuous culture under clinically relevant conditions has allowed us to introduce time to the growth system and selects SCV within the population. This study provides valuable insights into the generation of SCV which are not addressed in standard laboratory generated models and reveals new pathways for understanding persistent S. aureus infection which can potentially be targeted in future treatments of persistent S. aureus infection.
Filiaciones:
Lee J:
Department of Molecular and Biomedical Sciences, School of Biological Sciences, The University of Adelaidegrid.1010.0, Adelaide, South Australia, Australia
Research Centre for Infectious Disease (RCID), The University of Adelaidegrid.1010.0, Adelaide, South Australia, Australia
Australian Centre for Antimicrobial Resistance Ecology (ACARE), The University of Adelaidegrid.1010.0, Adelaide, South Australia, Australia
:
Department of Health and Genomics, Center for Advanced Research in Public Health, FISABIO Foundation, Valencia, Spain
:
Department of Health and Genomics, Center for Advanced Research in Public Health, FISABIO Foundation, Valencia, Spain
Vreugde S:
Department of Otolaryngology, Head and Neck Surgery, Basil Hetzel Institute, South Australia, Adelaide, Australia
Cooksley C:
Department of Otolaryngology, Head and Neck Surgery, Basil Hetzel Institute, South Australia, Adelaide, Australia
Crosby HA:
Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
Horswill AR:
Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
:
Department of Health and Genomics, Center for Advanced Research in Public Health, FISABIO Foundation, Valencia, Spain
Zilm PS:
Adelaide Dental School, The University of Adelaidegrid.1010.0, Adelaide, South Australia, Australia
Kidd SP:
Department of Molecular and Biomedical Sciences, School of Biological Sciences, The University of Adelaidegrid.1010.0, Adelaide, South Australia, Australia
Research Centre for Infectious Disease (RCID), The University of Adelaidegrid.1010.0, Adelaide, South Australia, Australia
Australian Centre for Antimicrobial Resistance Ecology (ACARE), The University of Adelaidegrid.1010.0, Adelaide, South Australia, Australia
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