Benefits of ID Consultation and ASP Collaboration

Contagion, Contagion, October 2020 (Vol. 05 No. 05) , Volume 05, Issue 05

Regulatory requirements have underscored the role of antimicrobial stewardship programs (ASPs), leading to their increased presence in hospitals.1 Although ASPs have demonstrated the ability to improve antimicrobial use and patient outcomes, concerns have been described regarding task-shifting away from infectious diseases consultation (IDC) because it purportedly antagonizes colleagues in other specialties; an overall reduction in IDCs has occurred as a result.2 In contrast, published data suggest that ASPs can actually increase the number of IDCs, since ASPs typically delineate roles separate from those of IDCs.3 IDC services are patient-focused and include direct communication with patients and making patient-specific plans, whereas ASPs are typically focused on activities that are more administrative in nature, such as developing institutional guidelines, updating antibiograms, and evaluating antimicrobial metrics.4 However, in hospitals with robust ASPs there may be overlapping patient care activities, because members of the ASP often perform prospective audits and provide patient-specific recommendations. So what is the impact of IDC in the presence of a well-established ASP?

Bork and colleagues sought to evaluate antibiotic use among patients with and without IDC in a hospital with robust ASP services.5 This was a cross-sectional retrospective analysis of inpatients at the University of Maryland Medical Center (UMMC), a large tertiary care center with a comprehensive IDC program consisting of 6 inpatient adult IDC services and primary ID service. Institutional policies promote pervasive influence by IDC, as IDC is required within 24 hours of ordering a restricted antimicrobial and is also required upon starting any antimicrobial for the treatment of infection among patients in the oncology ward, medical intensive care unit (ICU), or trauma services.

UMMC also has an established ASP with 2 ID physicians and 3 ID pharmacists. Prospective audit and feedback are the mainstay of the ASP, which is performed on all active antimicrobial orders started for treatment within 3-5 days of starting therapy for patients without IDC, and within 4-6 days for patients being seen by the IDC service. Antimicrobial appropriateness, along with the indication and any interventions, are documented in the electronic medical record for each antimicrobial reviewed.

The study included all antimicrobial prescriptions active for more than 2 days that were reviewed by the ASP over an 18-month time period. The primary outcome was antimicrobial appropriateness defined as (1) having an indication for antimicrobial treatment, and (2) using an antimicrobial consistent with institutional guidelines or using an antimicrobial that was otherwise justified by ASP review. Appropriate antimicrobial therapies were further categorized as either “guideline-concordant” or “guideline-discordant but justified.” The investigators performed several statistical analyses to mitigate limitations of the retrospective analysis, including multivariable logistic regression, stratification by primary service, and propensity score matching.

A total of 10,507 (6615 unique patient encounters) antimicrobial prescriptions met inclusion criteria. IDC was present in most (72%) of the antibiotics reviewed. Antimicrobial prescriptions with IDC were more likely to be a restricted antimicrobial and written for patients in the ICU. Patients with IDC were also more likely to have positive cultures and be colonized with organisms that were multidrug resistant.

Appropriate therapy was greater among antimicrobials with IDC compared with those without IDC (94% vs 84%; P <.0001). Unsurprisingly, “guideline-discordant but justified” antimicrobials occurred more frequently with IDC than without IDC (9% vs 5%; P <.0001). After propensity score matching, the sample size decreased to 3566 with relatively improved distribution of baseline characteristics. In the propensity score matched sample, IDC was positively associated with antimicrobial appropriateness (OR, 2.5; 95% CI, 2.1-3.0) and the difference in appropriate therapy remained (93% with IDC vs 85% without IDC; P <.0001). When stratified by primary service, IDC improved antimicrobial appropriateness among both the medical and surgical specialties, with the greatest benefit among surgical specialties. The authors conclude that IDC and ASPs may be synergistic.

Several considerations potentially limit the reproducibility of these results in other hospitals. The intensive and pervasive IDC and ASP services at the study site are one important reason. At UMMC, the ASP and IDC services appear well-established and appropriately resourced, allowing the evaluation of a large proportion of patients receiving antibiotics. Institutions with an imbalance of resources for the ASP and/or IDC services may not observe such high rates of antimicrobial appropriateness and the results may skew in favor of the service, with its improved ability to provide direct patient care services to a great proportion of patients. For example, in hospitals with ASPs that are unable to perform prospective audit and feedback on all antimicrobials, the baseline rate of appropriateness may be lower, potentially leading to a larger improvement with IDC. In this study, most patients were seen by IDC and all patients were prospectively evaluated by the ASP. Additionally, reviewer bias may have skewed the results, as only antimicrobials reviewed by the ASP were included in the analysis and appropriateness was determined by an unblinded ASP team member. Reviews were also performed later in the course of therapy for antimicrobials with IDC, which may have allotted more time for diagnostic tests and antimicrobial adjustments.

Overall, well-resourced centers with robust IDC services are best able to relate to these findings, which demonstrate the benefits of IDC even in the presence of a well-established ASP. Some centers, particularly those with other strong subspecialties, may have providers who are reluctant to consult ID. These findings underscore the benefits of bedside IDC services and add to the current body of published literature that supports the relationship between IDC and ASPs. ASPs can also use these data to quell fears of an ASP overtaking. Working together, IDC and ASPs can optimize antimicrobial use, particularly for more nuanced cases that fall outside of ASP guideline recommendations.

Highlighted Study: Bork JT, Claeys KC, Heil EL, et al. A propensity score matched study of the positive impact of infectious diseases consultation on antimicrobial appropriateness in hospitalized patients with antimicrobial stewardship oversight. Antimicrob Agents Chemother. 2020;64(8):e00307-20. doi:10.1128/AAC.00307-20

Cynthia Nguyen, PharmD, is an infectious diseases clinical pharmacy specialist at the University of Chicago Medicine. She is an active member of the Society of Infectious Diseases Pharmacists, Society for Healthcare Epidemiology of America, and American College of Clinical Pharmacy.


1. The Joint Commission. 2020 Comprehensive Accreditation Manual for Hospitals. Joint Commission Resources, 2019.

2. Sunenshine RH, Liedtke LA, Jernigan DB, Strausbaugh LJ; Infectious Diseases Society of America Emerging Infections Network. Role of infectious diseases consultants in management of antimicrobial use in hospitals. Clin Infect Dis. 2004;38(7):934-938. doi:10.1086/382358

3. Morrill HJ, Gaitanis MM, LaPlante KL. Antimicrobial stewardship program prompts increased and earlier infectious diseases consultation. Antimicrob Resist Infect Control. 2014;3:12. doi:10.1186/2047-2994-3-12

4. Beach JE, Ramsey TD, Gorman SK, Lau TTY. Roles of infectious diseases consultant pharmacists and antimicrobial stewardship pharmacists: a survey of Canadian tertiary care academic hospitals. Can J Hosp Pharm. 2017;70(6):415-422. doi:10.4212/cjhp.v70i6.1709

5. Bork JT, Claeys KC, Heil EL, et al. A propensity score matched study of the positive impact of infectious diseases consultation on antimicrobial appropriateness in hospitalized patients with antimicrobial stewardship oversight. Antimicrob Agents Chemother. 2020;64(8):e00307-20. doi:10.1128/AAC.00307-20