An Overview of ABSSSI

Peter L. Salgo, MD; Yoav Golan, MD; and Bruce M. Jones, PharmD, BCPS, identify the commonalities of ABSSSI, including the predominant pathogens, such as Staphylococcus aureus and Streptococcus, and gram-positive infections.

Peter L. Salgo, MD: Hello, and thank you for joining us today for this Contagion^® Peer Exchange^® panel discussion. Acute bacterial skin and skin structure infections (ABSSSI) have become a challenging medical problem often associated with high direct and indirect costs. These infections are responsible for an astounding 750,000 hospitalizations per year, representing a 17.3% increase in hospitalized ABSSSI patients from 2005 to 2011. If left untreated, these infections can cause potentially life-threatening infections in bones, joints, surgical wounds, bloodstream infections, heart valves, and lungs, to name just a few. This Peer Exchange^® panel of experts in infectious diseases is going to discuss the trends in ABSSSI incidence, cost considerations, and patient selection for outpatient parenteral antibiotic therapy.

I’m Dr. Peter Salgo, and I’m a professor of medicine and anesthesiology at Columbia University College of Physicians and Surgeons and an associate director of surgical intensive care at New York-Presbyterian Hospital. Participating today on our distinguished panel are Dr. Yoav Golan, an attending physician at Tufts Medical Center in Boston, Massachusetts, and associate professor at Tufts University School of Medicine, and Dr. Bruce Jones, infectious diseases clinical pharmacy specialist for St. Joseph’s/Candler Health System of Savannah, Georgia. Thank you so much for joining us. Let’s get right to the point and discuss some basic, simple definitions. How do you define acute bacterial skin and skin structure infections?

Yoav Golan, MD: Well, it’s important to remember, this is an FDA indication; that is, when new antibiotics are being approved.

Peter L. Salgo, MD: You are telling me, first of all, that it’s a bureaucratic definition, but there is also a clinical definition, too. So, how do we go about this?

Yoav Golan, MD: It’s not what we use in everyday medicine, and if you translate that to everyday medicine, it includes cellulitis, erysipelas. It includes abscesses, and it includes wound infections—this could be surgical wound infections, trauma-related wound infections, and so forth. Those 3 together make this FDA indication of ABSSSI.

Peter L. Salgo, MD: But it wouldn’t be a definition somewhere, by some bureaucratic standard, if there wasn’t a number in it. Do we know how big it needs to be to make that definition?

Bruce M. Jones, PharmD, BCPS: Absolutely. The FDA has established that it needs to be greater than 75 cm to be considered a major cutaneous abscess. They want to know that it’s a good size.

Peter L. Salgo, MD: That’s huge—75 square centimeters is a lot of centimeters.

Yoav Golan, MD: It’s the size of a baseball.

Peter L. Salgo, MD: The size of a baseball, yes—that’s a big infection. Just this once, I think we can all agree, you get 75 square centimeters involved, you have a problem—whether it’s cellulitis, erysipelas, or wound infection, that’s a big infection. Given that big of an infection, how big of a problem is ABSSSI?

Bruce M. Jones, PharmD, BCPS: In this day and age, it’s one of the most common infections that we’re seeing in inpatients that we deal with. In terms of emergency department visits, we’re seeing over 3 million a year; outpatient visits, over 14 million a year—so it is a big problem in society today.

Peter L. Salgo, MD: I’m not sure I’ve ever really focused on it quite like that. That’s a lot of infected tissue, so we can lump that together into a big skin infection. That’s a lot of people.

Bruce M. Jones, PharmD, BCPS: Absolutely.

Peter L. Salgo, MD: Is that getting bigger? Is it a bigger problem than it used to be? You read about it in the paper sometimes.

Bruce M. Jones, PharmD, BCPS: Absolutely. I think we’re seeing linear growth. If you look at the numbers now, every year we see more and more of these patients. They’re coming to physician offices, and where are they sending them? They’re sending them to the emergency departments.

Peter L. Salgo, MD: You hear stories in the popular press: There is some kid who’s a wrestler…he’s a hockey player…he’s a baseball player…and he comes in with some MRSA (methicillin-resistant Staphylococcus aureus) infection on his skin, and he loses an arm. Is that common?

Yoav Golan, MD: In the past, you actually needed to have risk factors to have Staphylococcus and to have resistant Staphylococcus known as MRSA. Nowadays, everyone can develop those, and, in fact, recurrent data from several studies in emergency departments show that MRSA is more prevalent than methicillin-susceptible, which is the susceptible version of this bacteria in the emergency department. In the past, you needed to be a pro athlete and then just an athlete, and now you don’t have to be an athlete at all, and those infections have become very, very common in the community. As you know, the MRSA version of Staphylococcus was particularly prevalent in ICUs many years ago, then in the wards, then in other institutions in the community, but now it’s prevalent in the community itself.

Peter L. Salgo, MD: The gram-positive organisms that we typically see are what? There are Staphylococcus and there are Streptococcus species, and you were talking about MRSA. It has always been my understanding that the resistance isn’t the same as its virulence—that is you can be resistant to antibacterial agents, but Staphylococcus is Staphylococcus. Is that fair?

Yoav Golan, MD: I would say so, and I think that skin infections are increasing tremendously in the community, among community providers, in the emergency department, in the hospital, and in other institutions. There are 2 main drivers to that when you talk about the pathogen. What is interesting is that the Staphylococcus we see circulating nowadays not only is more resistant to the common antibiotics that we use in the community but actually also is a more virulent strain. In other words, it’s a strain that’s more capable of causing infection. There was a recent study that was done among military recruits showing that if you are colonized with this strain of Staphylococcus, as compared with other strains of Staphylococcus, before your preliminary or first training, you are far more likely to get infected during the training. This is the Staphylococcus that is more capable of causing an infection, and the infection is harder to treat because the Staphylococcus is more resistant to antibiotics.

Peter L. Salgo, MD: Did I misspeak? I always thought that resistance is 1 thing, and then the virulence of the organism is another. Are you implying that there’s a link between antibiotic resistance and virulence?

Yoav Golan, MD: One way to look at antibiotic resistance is as a virulence factor, because the more resistant you are, the treatment options that we have are not as good. The likelihood that you get early, adequate therapy is reduced because there are fewer antibiotics that can be used reliably. The disease is going to run its course, and the infection is going to be more severe at the end of the day.

Peter L. Salgo, MD: Allow me to say in my own defense that academically I might be right but pragmatically I’m not. We were talking about gram-positives…When I was a medical student, it was always gram-positives in skin, but gram-negatives are out there, too, right?

Bruce M. Jones, PharmD, BCPS: Absolutely. I think if you look at specifically surgical-site infections as an example, if they include the gastrointestinal tract, I think gram-negatives come into play. We spoke earlier about how if you look at certain wound infections especially, if purulence is found, it leans more toward Staphylococcus. If you have a quick-growing cellulitis, for example, many times it’s Streptococcus.