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Virulence Genes of Staphylococcus aureus Associated With Keratitis, Conjunctivitis, and Contact Lens-Associated

Madeeha Afzal1, Ajay Kumar Vijay1, Fiona Stapleton1

  • 1School of Optometry and Vision Sciences, University of New South Wales, Sydney, NSW, Australia.

Translational Vision Science & Technology
|July 8, 2022
PubMed
Abstract

Insights

Staphylococcus aureus virulence genes differ between ocular infections like keratitis and conjunctivitis, and noninfectious events. Specific genes like hlg, hld, and scpA show distinct patterns, aiding in understanding ocular disease pathogenesis.

Area of Science:

  • Ophthalmology
  • Microbiology
  • Genetics

Background:

  • Staphylococcus aureus is a significant cause of various human ocular diseases.
  • These include infectious conjunctivitis, microbial keratitis (MK), and noninfectious corneal infiltrative events (niCIE).

Purpose of the Study:

  • To investigate the presence of known Staphylococcus aureus virulence genes in strains isolated from ocular infections (MK, conjunctivitis) and niCIE.
  • To identify potential virulence factors contributing to the pathogenesis of these distinct ocular conditions.

Main Methods:

  • Sixty-three S. aureus strains were analyzed: 23 from MK, 26 from conjunctivitis, and 14 from niCIE.
  • Polymerase chain reaction (PCR) was employed to detect the mecA gene and ten virulence genes (clfA, fnbpA, eap, coa, scpA, sspB, sspA, hla, hld, hlg) associated with MK, and two (pvl, seb) with conjunctivitis.

Main Results:

  • The mecA gene was more prevalent in infection strains (35%) than niCIE strains (7%).
  • Invasion genes hlg and hld were significantly higher in infection strains compared to niCIE strains.
  • The evasion gene scpA was found at a higher frequency in niCIE strains (86%) than in infection strains (45%).

Conclusions:

  • Higher frequencies of hlg and hld in infection-related strains suggest a role in pathogenesis.
  • The gene scpA may be a key virulence factor specifically in noninfectious corneal infiltrative events.
  • This research elucidates specific virulence factors contributing to ocular pathogenesis by S. aureus.

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