Published in the February 2015 issue of Today’s Hospitalist
WHEN IT COMES TO STUDYING antibiotic overuse in acute skin and skin-structure infections, researchers at Denver Health Medical Center in Denver have amassed quite a track record.
Between 2010 and 2014, they published four studies looking at inpatient prescribing patterns for cellulitis and cutaneous abscess. A common theme emerged in all their findings: Doctors in hospitals are prescribing a significant and unwarranted level of broad-spectrum gram-negative antibiotics.
Their latest research, published in the December 2014 issue of the Journal of Hospital Medicine, was a secondary analysis of two of their previously published studies. During this pass, the authors wanted to see if antibiotic-prescribing patterns for patients hospitalized with cellulitis or cutaneous abscess differed between diabetics and nondiabetics. Patients with infected ulcers or deep tissue infections were excluded.
Among the cases that produced a positive culture, 90% of the infections in diabetic patients and 92% of those in nondiabetics were due to gram-positive organisms. Gram-negative pathogens were isolated in only 7% and 12% respectively.
But researchers found that an alarming percentage of nondiabetic patients “44% “received some gram-negative therapy. Worse, that was the case for the majority of patients with diabetes: 54% were exposed to at least two days of antibiotics with broad gram-negative activity. Diabetics were also more likely to receive an antipseudomonal, the broadest-spectrum antibiotics, and to be prescribed fluoroquinolones at discharge.
Further, researchers found that the prescribing dichotomy between those groups was initiated after admission. In their analysis, the same number of patients in both groups who were prescribed antibiotics in the emergency or in-house urgent-care department had been started on some gram-negative therapy (31%).
Today’s Hospitalist talked to Timothy Jenkins, MD, an infectious diseases specialist who directs Denver Health’s antimicrobial stewardship program and is the lead author on all four studies.
What led you and your colleagues to start this line of research?
It really stemmed from our clinical experience in the hospital. We were getting requests for consults from hospitalists and surgeons on patients who had relatively uncomplicated skin infections but were on very broad-spectrum antibiotic regimens. So we felt that skin infections might be a particularly high-yield target in which to reduce unnecessary antibiotic use.
We also chose skin and soft-tissue infections because the vast majority are caused by gram-positive pathogens. Over the last decade, antibiotic resistance in gram-negative bacteria has become particularly worrisome, so we’re focusing our efforts around how to limit the use of agents with gram-negative activity to conditions where they are really necessary.
What do you think is behind this disproportionate prescribing for diabetic patients?
I suspect it is related to providers’ experience with diabetics who have more complicated infections, such as infected ulcers or osteomyelitis. There is a higher likelihood of gram-negative involvement in those types of infections, and national guidelines for such infections do recommend broad-spectrum therapy. I think inpatient physicians are extrapolating their experience with those treatment recommendations to these less complicated cases of cellulitis and abscess.
Your analysis did find that diabetic patients with cellulitis or abscess had some different clinical factors.
The diabetic group was older and more likely to have lower-extremity cellulitis. But lower-extremity cellulitis is typically caused by beta-hemolytic streptococci, so gram-negative therapy is not warranted in the vast majority of these infections. Certain clinical factors were also less common among diabetics like injection drug use and HIV infection.
Unfortunately, you also found a great deal of gram-negative prescribing among nondiabetics.
That’s an important point. Although diabetics were more likely to be exposed to broad gram-negative therapy, both groups had substantial exposure and present a major opportunity to reduce unnecessary use of these agents.
But efforts to change prescribing practices will have to involve many different provider groups, not just hospitalists. Those include providers starting empiric therapy in the emergency department or urgent care, orthopedic surgeons, general surgeons, housestaff, and others. That’s one of the significant challenges in improving antibiotic prescribing for these conditions.
Would more concrete guideline recommendations help?
Current guidelines do not specifically mention some conditions “like diabetes or injection-drug use “where patients are more likely to be exposed to broad-spectrum therapy. So specific statements in guidelines may help.
But many providers aren’t aware of national guidelines, or they aren’t comfortable following those guidelines at the bedside. In addition, guidelines suggest a number of treatment options, which may lead to confusion as to what the recommended treatment is at a given hospital. This is why you need local efforts to provide education and promote hospital-specific antibiotic utilization strategies.
One of your studies measured the effect of interventions that your team put in place to change gram-negative prescribing. What were your results?
Several years ago, we developed a clinical practice guideline to help manage skin infections. The intervention also included an educational campaign, peer champion advocates to promote the guideline’s use, quarterly audit of and feedback about prescribing practices to the departments that manage skin infections, and a CPOE order set.
We found a 45% decline in the use of broad gram-negative agents for both cellulitis and abscess and a nearly 25% reduction in therapy durations. We’re no longer performing the active components of the intervention. But based on unpublished internal data, clinicians have been able to sustain those prescribing changes.
Where do you go from here in your research?
Although we’re doing better with antibiotic selection and treatment durations for patients with skin infections, there is more work to be done on that front.
We’ve recently developed a smart-phone application with local antibiotic prescribing guidance that we hope will improve treatment choices at the point of care for a wide range of infections. We are also evaluating whether biomarkers such as CRP or procalcitonin might be useful laboratory tools to assess patients’ response to therapy and determine when antibiotics can be stopped.
Community-acquired pneumonia and urinary tract infections are also common infections that frequently lead to antibiotic overuse. We’ve shown similar improvements in prescribing for patients with community-acquired pneumonia through a guideline-based intervention. And we are currently developing an intervention to optimize empiric therapy ” with oral step-down antibiotic selection “and treatment durations for patients with urinary tract infections.
Phyllis Maguire is Executive Editor of Today’s Hospitalist.