Antimicrobial Stewardship in the Emergency Department: Does Your Institution Need an Emergency Department-Specific Antibiogram?

The importance of prompt empiric therapy is clear. Prompt empiric therapy leads to better survival among patients with both community- and hospital-acquired infections.

Citing a paper by Luna et al, Laurimay Larocco, PharmD, with WakeMed Health and Hospitals in Raleigh, North Carolina, impressed upon the audience that initial therapy with inadequate antimicrobials might lead to higher mortality rates and adverse clinical outcomes.

Dr Larocco explained that although empiric antibiotic therapy does not have the benefit of selection based on actual cultures, other factors may inform the decision of which antimicrobial to use. For instance, patient age, organ dysfunction (ie, kidney, liver), and pharmacokinetic factors may play a role in the selection. Additionally, the antibiogram for a given hospital may recommend use of one antibiotic over another.

Although hospitals use an overall antibiogram, Dr Larocco differentiated hospital antibiograms from unit-specific documentation of susceptibility. The benefits of a unit-specific antibiogram have been supported by several studies. Bryce and Smith compared the antibiotic susceptibility of isolates of Pseudomonas aerugenosa in the intensive-care unit (ICU) setting to isolates found in other parts of the same hospital and found a higher resistance rate in the ICU than elsewhere, which were reflected in 2 additional studies presented.

Offering a possible explanation for these findings, Dr Larocco emphasized that patients in a higher age range with more disabling conditions, higher prevalence of prior antibiotic use, and more implanted medical devices are at a higher risk for antibiotic resistance. Showing data that demonstrated the higher rate of long-term care residence, dialysis use, HIV infection, and a primary diagnosis of an infection, she explained that patients treated in the emergency department (ED) may be more prone to infection with isolates of bacteria that are resistant to antibiotic treatment. As a result, the importance of a separate antibiogram for this group to optimize outcomes can be visualized.

Using the case of a skin infection to demonstrate the difference between infections obtained in the hospital setting and infections from the community setting, Dr Larocco showed that clindamycin effectively treated skin infections in 67% of cases of hospital-acquired infections versus 90% of community-acquired infections. Similarly, higher cure rates were observed for skin infections acquired in the community setting with 2 other antibiotics.

Some challenges to developing a hospital-specific antibiogram include the lack of entries for the site of collection of blood and urine samples. This lack of information poses a serious challenge to retrospective collection of data for development of an antibiogram. However, minor changes to information technology might facilitate development of an ED-specific antibiogram.

The resulting susceptibility information might have several benefits, as described by Dr Larocco, including more timely selection of empiric antibiotic treatment, greater comfort with antibiotic selection among caregivers, and fewer escalations of therapy. To achieve these benefits, multidisciplinary support from pharmacy staff, laboratory technicians, and physicians is important. Additionally, once developed, the antibiogram would need to be embedded into prescribing software used in the ED.

Dr Larocco emphasized the differences between microbial isolate resistance patterns to antibiotics between patients in the overall hospital population versus those treated in the ED setting. The differences between these groups, apparent from multiple studies, might lead to clinically significant differences in which empiric antimicrobial therapies are most appropriate for treatment of common infections. Establishing an antibiogram might improve therapeutic outcomes for patients and increase the comfort level of prescribers and pharmacists with the choice of antibiotic therapy.