1789. Inpatient Penicillin Skin Testing: Outcomes from a Propensity-matched Case-control Study
Session: Poster Abstract Session: Antimicrobial Stewardship: Impact of Allergy
Saturday, October 6, 2018
Room: S Poster Hall
  • PST Prop Match FINAL.pdf (698.7 kB)
  • Background:

    Nearly 10% of patients report an allergy to penicillin, yet fewer than 10% are confirmed to have a true allergy. Reported allergy frequently leads to the use of costly, broad-spectrum or less effective antibiotics. We launched a penicillin skin testing (PST) service offering real-time skin testing for inpatients. Here we present clinical outcomes for the first 80 consecutively tested cases compared to propensity-matched controls.


    PST was performed on 80 adults with a reported penicillin allergy admitted to Duke University Hospital between 11/2016 and 3/2018. A logistic regression model predicting PST receipt was developed using a cohort of penicillin-allergic, untested adults. Covariates included age, gender, diagnosis, and Charlson co-morbidity index. Using this model, the PST cases were propensity-matched 1:1 with untested, penicillin-allergic controls admitted in the preceding year (10/2015-10/2016). Rates of first-line antibiotic receipt were compared between PST cases and their propensity-matched controls.


    PST cases and controls had similar demographics, reported allergies, diagnoses and co-morbidities. Cases were more likely to receive a first-line antibiotic (83% vs 57%, p=0.003, table 1). Rates of clinical cure were similar between groups. Ninety-day recurrence and C. difficile infection were numerically higher in the untested group but did not reach statistical significance. A single allergic reaction (rash upon receipt of a cephalosporin) occurred in the PST group.


    Penicillin skin-testing significantly increased the proportion of patients receiving first-line antibiotics. While rates of recurrence and C. difficile infection were lower for skin-tested patients, these differences did not reach statistical significance. As this study was not expressly powered to detect such differences, we plan to reassess these outcomes once we have accrued a sufficiently large cohort of tested patients.

    Table 1: Outcomes.

    PCN Skin Tested

    N=80 (%)


    N=80 (%)


    Clinical Outcomes:

      First-line antibiotics

    53 (82.8)

    31 (57.4)


      Clinical cure

    58 (95.1)

    57 (91.9)


      90-day recurrence

    3 (5.2)

    8 (13.3)


      C. difficile infection

    2 (3.1)

    4 (6.3)


      Allergic reaction

    1 (1.5)

    0 (0)


    Christina Sarubbi, PharmD1, Rebekah Wrenn, PharmD1, Nicholas Turner, MD2, Renee Kleris, MD3, Jessica Seidelman, MD1, Patricia Lugar, MD4, Cristine Radojicic, MD5, Rebekah W. Moehring, MD, MPH2 and Deverick J. Anderson, MD, MPH, FIDSA, FSHEA1, (1)Duke Center for Antimicrobial Stewardship and Infection Prevention, Durham, NC, (2)Division of Infectious Diseases, Duke University Medical Center, Durham, NC, (3)Department of Pediatrics, Division of Allergy and Immunology, Durham, NC, (4)Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, Durham, NC, (5)Allergy and Immunology, Duke University Health System, Durham, NC


    C. Sarubbi, None

    R. Wrenn, None

    N. Turner, None

    R. Kleris, None

    J. Seidelman, None

    P. Lugar, None

    C. Radojicic, None

    R. W. Moehring, None

    D. J. Anderson, None

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 3rd with the exception of research findings presented at the IDWeek press conferences.