ARMOR study shows high antibiotic resistance rates for S. aureus, coagulase-negative staphylococci

Overall antibiotic resistance rates have not increased in the last 5 years, but resistance is high for some Staphylococcus aureus and coagulase-negative staphylococci isolates, according to a study.

Many strains showed multi-drug resistance rates that correlated with reports for non-ocular staphylococcal isolates in the literature, the study authors said.

“Until rapid diagnostic methods are available to guide treatment choices, clinicians should consider these data to guide the empirical treatment of ocular infections,” they said.

In the first 5 years of the ARMOR study, the authors analyzed antibiotic resistance profiles and trends for more than 3,000 ocular isolates. The study began in 2009 and looked at antibiotic resistance among S. aureus, coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Haemophilus influenzae and Pseudomonas aeruginosa isolates from ocular infections.

Investigators collected 1,169 S. Aureus isolates, 992 CoNS isolates, 330 S. pneumoniae isolates, 357 H. influenzae isolates and 389 P. aeruginosa isolates, totaling 3,237 isolates, over a 5-year period.

Methicillin resistance was observed in 493 S. aureus isolates and 493 CoNS isolates. Methicillin resistance correlated significantly with concurrent resistance to fluoroquinolones, aminoglycosides and macrolides (P < .001).

Staphylococcal isolates were found to be susceptible to vancomycin.

The resistance rate among S. pneumoniae isolates was highest for azithromycin. P. aeruginosa and H. influenzae showed low resistance.

Staphylococci resistance to methicillin did not increase during the 5-year period. There were slight decreases in resistance to ciprofloxacin in CoNS and methicillin-resistant CoNS and to tobramycin in CoNS.

Staphylococcal isolates from elderly patients and S. aureus isolates from the southern U.S. were significantly more likely to be resistant to methicillin than other isolates (P < .001). – by Matt Hasson

Disclosure: Asbell reports she serves on the advisory board for Valeant and Bausch + Lomb. The other authors report no relevant financial disclosures.

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Source:

Asbell PA, et al. JAMA Ophthalmol. 2015;doi:10.1001/jamaophthalmol.2015.3888.