ARVO LIVE: ARMOR study and antibiotic resistance

Ophthalmology Times® talked with Penny Asbell, MD, FACS, MBA, about the ARMOR study and antibiotic resistance at this year's ARVO meeting.

Video transcript

Editor’s note: Transcript lightly edited for clarity.

Penny Asbell, MD, FACS, MBA:

Hi, I'm Penny Asbell. I'm here at ARVO 2023, and I'm associated with the University of Memphis, Department of Bioengineering, and we're going to be talking about antibiotic resistance part of the ARMOR study. You know, we all get patients who have infections, and we want to know how to treat them right away.

I think that's where the ARMOR study comes in. It's been a study that's been collecting isolates over 10 years. We started actually in 2009, and we took a look specifically at our staff isolates. When you look at infections in the eye, staph is probably the most common offending organism. So, we separated it into staph aureus and coagulase-negative staph, and then we further took a look at resistance, specifically methicillin resistance.

As you recall, back at the beginning of this project, methicillin-resistance was very common. Good news: It's actually decreased over this past decade. So when you look at staph aureus, we're about 50% decreased. When you look at coagulase-negative staph, like staph epidermidis, it's down, but it's still almost 40% for methicillin resistance.

Well, what does this mean to us as clinicians? When you're getting an organism that is methicillin-resistant, the chances are it's resistant to at least three other classes of antibiotics, meaning it's highly resistant, and just may not work with the antibiotic that you pick out. And, if you look at those methicillin-resistant organisms, almost 80% of them are going to be resistant to multiple antibiotics. So we really have to pick wisely, particularly at the beginning, before we have culture results, to better determine what's going to work clinically.

What about the antibiotics? If you look at vancomycin, it's done pretty well that whole period of time, still very low MICs, the measurement of potency in the laboratory. Another good news is besifloxacin, which is commercially available, also continues to be very low, almost like vancomycin, frankly, and its MIC numbers, and it really hasn't changed at all since 2009.

So we do have some good options, both by compounding and available as a prescription product to treat even those methicillin-resistant organisms. But keep it in mind, you're still gonna have to deal with resistance; you're gonna still have to deal with methicillin resistance, and some of those organisms may be very tough to treat.