June 2021
Volume 62, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2021
Antimicrobial susceptibility of Staphylococcus aureus from different ocular conditions
Author Affiliations & Notes
  • Madeeha Afzal
    School of Optometry and Vision Sciences, University of New South Wales, Sydney, New South Wales, Australia
  • Ajay Kumar Vijay
    School of Optometry and Vision Sciences, University of New South Wales, Sydney, New South Wales, Australia
  • Fiona Stapleton
    School of Optometry and Vision Sciences, University of New South Wales, Sydney, New South Wales, Australia
  • Mark Willcox
    School of Optometry and Vision Sciences, University of New South Wales, Sydney, New South Wales, Australia
  • Footnotes
    Commercial Relationships   Madeeha Afzal, None; Ajay Kumar Vijay, None; Fiona Stapleton, None; Mark Willcox, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2021, Vol.62, 403. doi:
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    • Get Citation

      Madeeha Afzal, Ajay Kumar Vijay, Fiona Stapleton, Mark Willcox; Antimicrobial susceptibility of Staphylococcus aureus from different ocular conditions. Invest. Ophthalmol. Vis. Sci. 2021;62(8):403.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Staphylococcus aureus is a frequent cause of eye infections, with isolates exhibiting increased antimicrobial resistance to commonly prescribed antibiotics. This study aimed to determine the antimicrobial susceptibility patterns and virulent determinants of S. aureus strains isolated from infectious and non-infectious adverse events from USA and Australia.

Methods : 51 strains of S. aureus from different ocular conditions (11 microbial keratitis [MK], 26 conjunctivitis and 14 from non-infectious contact lens corneal infiltrative events (niCIEs), were analysed for susceptibility to antibiotics commonly used to treat these conditions, using the broth dilution method. The presence of 13 virulence genes was determined by PCR.

Results : All strains were sensitive to vancomycin (100%) and gentamicin (98%). The susceptibility to other antibiotics decreased in the following order: chloramphenicol (80%), oxacillin (70%), ciprofloxacin (45%), ceftazidime (13%), azithromycin (10%) and polymyxin B (2%). All Australian MK strains but only 11% of USA MK strains were susceptible to ciprofloxacin and oxacillin (p = 0.107). 75% of Australian conjunctivitis strains from Australia were susceptible to ciprofloxacin compared to 37% of USA conjunctivitis strains (p=0.278). Most (90%) Australian niCIEs and USA conjunctivitis (96%) but only 55% of USA MK strains were susceptible to chloramphenicol (p = 0.0036). 84% of all strains were multi-drug resistant. All strains possessed Eap which aids in adhesion. Most strains possessed fnbpA, except 2 strains from niCIEs. No MK possessed clfA whereas all strains form niCIEs and 61% of conjunctivitis strains possessed clfA gene. pvl (Panton-Valentine leukocidin), which is associated with community-acquired MRSA, was present in most Australian MK and conjunctivitis strains but not in non-infectious strains (p = 0.018). Australian conjunctivitis strains were more likely to possess pvl than USA conjunctivitis strains (p = 0.031).

Conclusions : Knowledge of the rates of resistance to antibiotics may be important in decisions on treating these diseases. The differences in possession of virulence genes may be related to the pathogenesis of these conditions.

This is a 2021 ARVO Annual Meeting abstract.

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