DISCUSSION

In this survey of primary-care residents at an academic medical center, we found that antibiograms are infrequently recognized as a resource when making antibiotic prescribing decisions. When asked an open-ended question about the resources they would draw from to select appropriate empiric antibiotic regimens for the clinical vignettes, only 12.3% identified the antibiogram as a reference despite the majority (89.6%) subsequently reporting being aware of this tool. Only ~70% of residents felt comfortable using an antibiogram or had used one before to aid in prescribing decisions, and less than half knew how to access the institutional antibiogram. Individuals with infectious diseases experience were more likely to have used the institutional antibiogram previously but were equally uncomfortable as other residents with using antibiograms in practice. Evaluation of the other responses to the clinical vignettes suggested weaknesses in respondents’ ability to determine appropriate empiric antibiotic regimens in scenarios where clinical guidelines and treatment pathways do not provide explicit recommendations for the specific patient case. In our survey, the clinical vignettes were developed to require some degree of clinical judgment beyond what could be identified in the relevant guidelines and resources. Furthermore, we refrained from directly asking questions regarding antibiograms until the final page of the survey to limit influencing respondents.

Our findings are consistent with a previous survey of medical residents and fellows at an academic center that revealed that 64% of respondents had never used the hospital’s antibiogram and that 61% did not know how to find it.Reference Mermel, Jefferson and Devolve ⁷ Similar results were observed with physicians and medical students, suggesting that the observed lack of comfort and familiarity with antibiograms may arise in medical school and persists as students become residents and, later, autonomous physicians.Reference Abbo, Cosgrove and Pottinger ^{5 ,} Reference Giblin, Sinkowitz-Cochran and Harris ^{6 ,} Reference Evans, Rogers, Burns, Lopansri and Weaver ⁸ Our survey provides greater context to these findings with the addition of clinical vignettes to assess residents’ antibiotic prescribing decisions in hypothetical cases. In these cases, only 12.3% of residents recognized antibiograms as a possible resource for guiding antibiotic prescribing, highlighting a disconnect between awareness (89.6% of respondents) and use. In addition to issues of accessibility, the limited antibiogram use by the residents in our study may be due to a perceived lack of need. Compared to many other urban facilities across the United States, our institution has relatively low rates of resistance to most antimicrobials. As such, medical residents may not feel that consulting an antibiogram is beneficial because many antibiotics may provide adequate empiric coverage. However, antibiogram use may encourage residents to prescribe empiric therapy with narrower-spectrum agents; thus, antibiograms may be used as a tool to support antimicrobial stewardship efforts.

While resident performance on the clinical vignettes was not the primary objective of the survey, we observed several important patterns in the responses. Approximately half of residents did not specify all the pathogens against which to direct empiric antibiotic therapy or recommend antibiotic regimens with appropriate coverage. Furthermore, there was no association between successfully identifying which bacteria to target and providing an appropriate antibiotic regimen. Several factors may influence the prescribing patterns we observed in the clinical vignettes. Surveys of medical students in the United States and Europe indicate that students feel insufficiently prepared to describe the spectrum of different antimicrobials or to select the best one for a specific infection and that additional training in this area is desired.Reference Abbo, Cosgrove and Pottinger ^{5 ,} Reference Dyar, Pulcini, Howard and Nathwani ⁹ However, 61% of respondents in our sample were in their second or later year of training, and approximately half had completed an infectious diseases rotation. While those who had completed an infectious diseases rotation were more likely to have used an antibiogram previously, they were no more likely to provide appropriate responses to either clinical vignette. This finding suggests that potential gaps in medical school curricula may persist inresidency and current resident training in infectious diseases does not sufficiently close these gaps. Enhancing education focused on infectious diseases pharmacotherapy and antibiogram interpretation throughout the medical curriculum and postgraduate training may be needed to improve antibiogram interpretation skills and antimicrobial prescribing decisions. Nori et alReference Nori, Madaline and Munjal ¹⁰ recently described a strategy of recurring case-based lectures coupled with distribution of antibiograms as a way to provide postgraduate education related to antimicrobial use; this approach resulted in a sustained improvement in antibiotic appropriateness over 20 months. This program was part of a larger education initiative that may not be feasible at all institutions. Other experts have suggested that antimicrobial education should be part of physician revalidation and accreditation and that antimicrobial stewardship teams should incorporate education into audit and feedback activities.Reference Abbo, Sinkowitz-Cochran and Smith ¹¹

Several limitations should be considered when interpreting the results of this study. Because our survey was distributed to a small sample of residents attending educational conferences and response was voluntary, our findings may be susceptible to response bias. While our response rate for disseminated surveys was 98%, respondents may differ from residents who did not attend educational conferences and thus could not participate in the survey. Another limitation is the generalizability of our findings. This is a small, cross-sectional survey of trainees at a single institution, and we limited our survey to primary-care residents in family medicine, internal medicine, and pediatric medicine. Consequently, our results may not apply to other resident cohorts, nonresident physicians, or other health systems. Furthermore, most respondents in our survey were from the internal medicine program, so any application of our results to family medicine and pediatric residents should be done cautiously, recognizing their relatively small representation in our data. Because this was a cross-sectional study, we could not assess improvements in antibiogram use and clinical performance over time. While we did evaluate relationships between antibiogram knowledge and year of residency, our lack of any significant improvements with time may be due to differences between residency classes rather than a lack of change over time. Future studies should consider including trainees from multiple training programs and institutions and assess responses throughout residency. Additional studies should also include more targeted questions to better identify and understand barriers to antibiogram use beyond that of accessibility. Finally, when evaluating residents’ performance in the clinical vignettes, it is important to remember that the clinical vignettes were composed of hypothetical case scenarios and may not represent actual clinical scenarios in which antibiotics are prescribed.

In conclusion, our results indicate that medical residents are aware of hospital antibiograms, but many have never used one or are not comfortable using it to guide antibiotic prescribing. More importantly, less than half of respondents were even aware of how to access the institutional antibiogram. While efforts to improve antibiogram accessibility and increase proficiency with their use may improve antibiogram utilization and appropriate empiric antibiotic prescribing, broader efforts focused on providing more applied education about infectious disease therapies may be needed to maximize the utility of antibiograms and meaningfully affect antibiotic prescribing decisions.