Related Experiment Video
Updated: May 19, 2026
07:10
A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
Published on: February 19, 2019
Evolutionary blueprint for host- and niche-adaptation in Staphylococcus aureus clonal complex CC30
Martin J McGavin1, Benjamin Arsic, Nicholas N Nickerson
1Department of Microbiology, Schulich School of Medicine and Dentistry, Siebens Drake Research Institute and Centre for Human Immunology, University of Western Ontario, London ON, Canada. martin.mcgavin@ schulich.uwo.ca
Frontiers in Cellular and Infection Microbiology
|August 25, 2012
Summary
Staphylococcus aureus CC30 Clade 3 strains have evolved reduced virulence and adapted to specific niches. These hospital-associated MRSA and MSSA strains show genetic changes favoring adaptation over hyper-virulence.
Area of Science:
- Microbiology
- Evolutionary Biology
- Genomics
Background:
- Staphylococcus aureus clonal complex CC30 has a long history of causing infectious epidemics.
- Phylogenetic analyses revealed three major branches (Clades 1-3) within CC30.
- Clades 1 and 2 are hyper-virulent, while Clade 3 exhibits attenuated virulence.
Purpose of the Study:
- To investigate the evolutionary adaptations of Staphylococcus aureus CC30 Clade 3 strains.
- To assess the hypothesis that Clade 3 has evolved for niche adaptation.
Main Methods:
- In silico genome comparisons of 15 public domain CC30 genomes.
- Analysis of single nucleotide polymorphisms (SNPs) and other genetic traits.
- Phylogenetic analysis and comparative genomics.
Main Results:
- Clade 3 strains possess SNPs affecting alpha-hemolysin (Hla) production and accessory gene regulator (agr) signaling.
- Common Clade 3 traits include tryptophan auxotrophy, truncated IsdH, loss of toxin-antitoxin modules, and acquisition of SaPI4/SaPI2.
- S. aureus MN8 (Clade 3) shows unique ISSau2 insertion and enhanced toxic shock syndrome toxin (tst) production.
Conclusions:
- Clade 3 strains demonstrate an evolutionary trajectory towards niche adaptation.
- Genetic modifications in Clade 3 contribute to reduced virulence and specialized functions.
- These findings provide insights into the evolution of bacterial pathogenicity and adaptation.
Related Concept Videos
01:29Staphylococcal Skin Infections
Staphylococcus aureus is a Gram-positive coccus that resides harmlessly on the skin and mucous membranes of healthy individuals. When the skin barrier is breached, it can shift from a commensal to an opportunistic pathogen. This transition is facilitated by surface adhesins, such as clumping factor B and S. aureus surface protein G (SasG), which bind to structural proteins, including loricrin and cytokeratin, in the damaged epidermis. Protein A, another key factor, binds the Fc region of...
01:24Evolution of New Traits in Microbes
Microorganisms evolve rapidly due to their large population sizes and short generation times, often exhibiting measurable changes within days under laboratory conditions. Natural selection acts on standing genetic variation, enabling the retention and amplification of beneficial traits that confer fitness advantages in changing environments.Adaptive Pigment Regulation in RhodobacterIn Rhodobacter, a genus of purple non-sulfur bacteria, light-harvesting pigments such as bacteriochlorophyll and...
01:25Clinical Significance of Antibiotic Resistance
Methicillin-resistant Staphylococcus aureus (MRSA) presents a critical public health threat, arising from its capacity to resist β-lactam antibiotics due to acquisition of the mecA gene within the staphylococcal cassette chromosome mec (SCCmec). This gene encodes penicillin-binding protein 2a (PBP2a), which impairs binding efficacy of methicillin and other β-lactams. MRSA has evolved into distinct clonal lineages impacting humans and animals alike, reinforcing its significance within the One...
01:16Transduction
Among the three main modes of HGT—transformation, conjugation, and transduction—transduction is unique in that it is mediated by bacteriophages, or bacterial viruses.Transduction occurs in two ways. Generalized transduction occurs during the lytic cycle of a bacteriophage infection. In this process, bacteriophages infect bacterial cells, replicate within them, and ultimately cause cell lysis, releasing newly assembled virions. Occasionally, random fragments of the bacterial genome are...
01:08Evolution of Microbial Genome
Microbial genome evolution is a highly dynamic process shaped by continual gene gain and loss across species and strains. This genomic flexibility allows microorganisms to adapt rapidly to environmental pressures and interactions with other organisms. Central to understanding this diversity is the distinction between the core and pan genomes.The core genome comprises the genes shared by all sampled strains of a species, representing essential functions needed for fundamental cellular processes.
01:25Mechanism of Antibiotic Resistance in MRSA
Antibiotic resistance in bacteria arises when microorganisms evolve the ability to withstand drugs designed to kill them or inhibit their growth, rendering once-effective treatments useless. This phenomenon, driven by genetic change and selection under antibiotic exposure, poses a profound threat to modern medicine. Mechanisms include drug-inactivating enzymes (e.g., β-lactamases), efflux pumps that eject antibiotics, mutations altering antibiotic targets, decreased drug uptake, and acquisition...