Related Experiment Video

Updated: May 14, 2026

A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
07:10

A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues

Published on: February 19, 2019

Virulence gene and expression analysis of community-associated methicillin-resistant Staphylococcus aureus causing

Wei-Chun Hung1, Hiromitsu Mori, Sayaka Tsuji

  • 1Division of Bacteriology, Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.

Journal of Infection and Chemotherapy : Official Journal of the Japan Society of Chemotherapy
|February 2, 2013
PubMed

Insights

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) can cause rare iliopsoas abscesses (IPAs). This study identifies a novel CA-MRSA strain variant responsible for IPA and discitis, linked to skin infections and exotoxin-mediated symptoms.

Area of Science:

  • Infectious Diseases
  • Microbiology
  • Genetics

Background:

  • Iliopsoas abscesses (IPAs) caused by methicillin-resistant Staphylococcus aureus (MRSA) are uncommon, but community-associated MRSA (CA-MRSA) strains may be emerging as a cause.
  • Previous reports in Japan documented CA-MRSA strains in adolescent athletes, highlighting the potential for diverse clinical presentations.
  • Intractable skin conditions can serve as a potential entry point for invasive bacterial infections.

Observation:

  • A 62-year-old man with severe eczema developed IPAs and discitis (L1-L2).
  • CA-MRSA strain NN55 was isolated from blood, pus, and joint fluid, suggesting an origin from the patient's eczema.
  • The patient presented with systemic myalgia and severe thrombocytopenia, potentially due to an exotoxin.

Findings:

  • Strain NN55, a variant of ST8 CA-MRSA/J (ST8 CA-MRSA/Jv), was identified. It possesses specific genetic markers, including a novel subtype of SCCmecIV encoding CWASP/J.
  • NN55 exhibited enhanced expression of cytolytic peptide genes (psmα and hld) and gentamicin resistance.
  • Unlike other ST8 strains, NN55 lacked the SaPIj50 island encoding toxic shock syndrome toxin-1 (TSST-1).

Implications:

  • The findings suggest that CA-MRSA strains, through adhesins and cytolytic peptides (excluding PVL and TSST-1), play a significant role in the pathogenesis of IPAs.
  • This study highlights the potential for CA-MRSA to cause severe musculoskeletal infections originating from skin infections.
  • The specific mechanisms causing systemic myalgia and thrombocytopenia in this case warrant further investigation.

More Related Videos

Identification of Virulence Markers of Mycobacterium abscessus for Intracellular Replication in Phagocytes08:34

Identification of Virulence Markers of Mycobacterium abscessus for Intracellular Replication in Phagocytes

Published on: September 27, 2018

Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)12:18

Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus (MRSA)

Published on: February 9, 2011

Related Concept Videos

Clinical Significance of Antibiotic Resistance01:25

Clinical 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...
Staphylococcal Skin Infections01:29

Staphylococcal 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...
Mechanism of Antibiotic Resistance in MRSA01:25

Mechanism 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...
Gene Regulation in Microbial Communities: Quorum Sensing01:28

Gene Regulation in Microbial Communities: Quorum Sensing

Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
Regulation of Bacterial Virulence01:28

Regulation of Bacterial Virulence

Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
Bacterial Gastroenteritis01:18

Bacterial Gastroenteritis

Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...