Ocular TRUST: nationwide antimicrobial susceptibility patterns in ocular isolates

Area of Science:

• Ophthalmology
• Microbiology
• Infectious Diseases

Background:

• The Ocular Tracking Resistance in U.S. Today (TRUST) program monitors antimicrobial resistance in common ocular pathogens.
• Understanding resistance patterns is crucial for effective treatment of eye infections.

Purpose of the Study:

• To evaluate the in vitro antimicrobial susceptibility of ocular isolates of Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae.
• To assess the activity of various antibiotics, including fluoroquinolones, against these pathogens.

Main Methods:

• Laboratory investigation of prospectively collected and archived ocular isolates.
• Antimicrobial susceptibility testing using minimum inhibitory concentration (MIC90) breakpoints.
• Classification of Staphylococcus aureus isolates as methicillin-susceptible (MSSA) or methicillin-resistant (MRSA).

Main Results:

• Fluoroquinolones demonstrated consistent activity against MSSA, S. pneumoniae, and H. influenzae.
• All S. pneumoniae isolates were susceptible to gatifloxacin, levofloxacin, and moxifloxacin.
• High-level in vitro resistance to fluoroquinolones was observed in MRSA isolates (15.2% susceptibility).
• Trimethoprim showed high activity against MRSA.

Conclusions:

• Fluoroquinolones remain effective against MSSA, S. pneumoniae, and H. influenzae.
• Ocular S. pneumoniae maintained high susceptibility to newer fluoroquinolones despite systemic use.
• High MRSA resistance necessitates considering alternative therapies when MRSA is suspected.