Beta-lactam testing in antimicrobial stewardship increases use of preferred antibiotics

Using beta-lactam allergy skin testing in antimicrobial stewardship programs significantly increased the use of preferred therapies without increasing the risk for adverse drug reactions in three hospitals, researchers in Canada reported.

“Reported allergy to beta-lactams is detrimental to patients with infectious diseases,” Jerome A. Leis, MD, MSc, of the division of infectious diseases at Sunnybrook Health Sciences Centre, Toronto, and colleagues wrote.  “These patients frequently receive less effective second-line therapies due to their allergy and broader spectrum antimicrobial agents that contribute to the development and spread of antimicrobial resistance. As most patients with a reported beta-lactam allergy could safely tolerate beta-lactams, promoting their use when clinically indicated is increasingly regarded as a function of antimicrobial stewardship.”

The researchers further noted that 2016 guidelines on antimicrobial stewardship called for use of beta-lactam allergy skin testing. However, the test “is not routinely available to institutions that lack expertise in allergy and immunology.”

Leis and colleagues performed a pragmatic multicenter prospective study of three hospitals. Antimicrobial stewardship teams were trained to offer the test for patients who had infectious diseases and reported beta-lactam allergies, with training at each hospital conducted in staggered 3-month intervals. The main outcome of the study was the proportion of patients who received preferred treatment with beta-lactams.

A total of 827 patients had reported beta-lactam allergies over 15 months of follow-up, the researchers reported. Penicillin was the specific allergen reported in 557 (88%) cases, a cephalosporin was the allergen in 7% (n = 43) of cases and both in 5% (n = 32).  However, Leis and colleagues reported that among more than three quarters of patients (76%; n = 632), beta-lactam therapy was the preferred treatment.

Half of patients (50%; n = 124 of 246) received preferred beta-lactam therapies based on their histories during the baseline period, Leis and colleagues wrote. This rose to 60% (n = 232 of 386; P = .02) during the intervention period, and rose again to 81% (n = 313 of 386) after the administration of beta-lactam allergy skin testing (P < .001). There was no increase in the incidence of adverse drug reactions, the researchers reported (4% vs. 3%; P = .04).

After researchers adjusted for correlation between hospitals and patient variables, they reported that the intervention period was associated with a 4.5-fold increased likelihood that patients would be treated with preferred beta-lactam therapy (95% CI, 2.4-8.2).

Leis and colleagues noted that the study was limited by the relatively small sample size and by the fact that the definition of preferred therapy was not standardized across individual hospitals. They noted, however, that definitions remained consistent throughout the study period.

“Our study demonstrates [the] feasibility of performing [beta-lactam allergy skin testing] as an antimicrobial stewardship activity to safely promote the use of preferred beta-lactam therapy, especially when the history is not sufficient to exclude a severe IgE-mediated reaction,” the researchers wrote. “Longer term studies are needed to better assess the safety and clinical impact of this [antimicrobial stewardship program] intervention.” – by Andy Polhamus

Disclosure: The researchers report no relevant financial disclosures.