Antibiotic resistance associated with staphylococcal ocular isolates
Antibiotic resistance among commonly used topical antibiotics is significant, first author of the ARMOR study results told Healio/OSN.
“The ARMOR surveillance study gives us an incredible view of eye infections over 10 years in the U.S.,” Penny A. Asbell, MD, MBA, of the department of ophthalmology at the University of Tennessee Health Science Center in Memphis, said.
The study, which looked at more than 6,000 isolates from 88 sites across 41 states, determined that more than one-third of Staphylococcus aureus and nearly one-half of coagulase-negative staphylococci (CoNS) ocular isolates were methicillin-resistant, Asbell said.
Of 6,091 isolates included in longitudinal data from the ARMOR study, 34.9% of 2,189 S. aureus isolates were resistant to oxacillin/methicillin, 33.5% were resistant to ciprofloxacin, and 59.7% were resistant to azithromycin.
Antibiotic resistance to oxacillin/methicillin was 49.3%, or 871 of 1,765 CoNS isolates.
“Multidrug resistance was very common, especially in methicillin-resistant isolates,” Asbell said. Furthermore, about three-fourths of Staphylococcus isolates were multidrug-resistant, she said.
Resistance rates to all antibiotics tested except azithromycin and penicillin were less than 10% among S. pneumoniae isolates. For azithromycin, the rate was 36.3% and for penicillin it was 32.2%. Overall antibiotic resistance was low for the 767 Pseudomonas aeruginosa and 780 Haemophilus influenzae isolates included in the report.
Methicillin-resistant S. aureus isolates and CoNS isolates were significantly more likely to be simultaneously resistant to other antibiotic drug classes than methicillin-susceptible S. aureus and CoNS isolates.
“If local cultures are done and results show resistance, be aware that multidrug resistance might be in play,” Asbell said. “Clinicians should pick the antibiotic to use wisely and use recent available data.”
The ARMOR data may be helpful for the initial antibiotic selection and for revising treatment if the patient is not responding, she said.