Issue: November 2017
October 16, 2017
2 min read

Reported penicillin allergy increases SSI risk

Issue: November 2017
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Patients with a documented penicillin allergy had an increased risk for developing surgical site infections, which researchers linked to the use of second-line perioperative antibiotics.

“This study has direct clinical significance,” Kimberly Blumenthal, MD, MSc, of the Division of Rheumatology, Allergy and Immunology, the Medical Practice Evaluation Center and the Lawrence Center for Quality and Safety at Massachusetts General Hospital, said in a press release. “We already know that more than 95% of patients who believe they have penicillin allergy can actually tolerate the drug, which indicates that preoperative penicillin evaluation could effectively reduce surgical site infections (SSIs) in these patients.”

According to Blumenthal and colleagues, SSIs are responsible for 40% of all health care-associated infections in hospitalized patients and cost an estimated $25,000 per case. Cefazolin is often recommended for surgical patients to reduce the incidence of SSIs. However, non-beta-lactam antibiotics such as clindamycin and vancomycin may be used as an alternative option for patients with a documented penicillin allergy.

The researchers conducted a retrospective cohort study to assess the impact of a reported penicillin allergy on the incidence of SSIs. Their analysis included 8,358 patients who underwent 9,004 procedures, including hip arthroplasty (n = 2,624), knee arthroplasty (n = 2,439), hysterectomy (n = 1,560), colon surgery (n = 1,250) and coronary artery bypass grafting (n = 1,131) at Massachusetts General Hospital from 2010 through 2014. The results were presented at IDWeek and published in Clinical Infectious Diseases.

Overall, 11% of patients had a reported penicillin allergy and 241 had an SSI. The proportion of patients who developed an SSI was higher among those with a reported penicillin allergy than those without one. After adjusting for multiple factors, the researchers estimated that a reported penicillin allergy increased the odds of developing an SSI by 50% (adjusted OR = 1.51; 95% CI, 1.02-2.22). In a multivariable marginal structural model, the effect of reporting a penicillin allergy on SSI incidence was “entirely due to the use of beta-lactam alternative perioperative antibiotics,” Blumenthal and colleagues wrote.

“This implies that the increased SSI risk is potentially modifiable if patients with a reported penicillin allergy could receive first-line beta-lactam antibiotic prophylaxis after a negative penicillin allergy evaluation,” they added.

A review of reported penicillin reaction histories revealed that all but five patients in the cohort may have been able to tolerate cefazolin. However, only 12.2% of patients with a reported allergy received the drug vs. 92.4% who did not report a penicillin allergy. Instead, patients with a reported allergy were more likely to receive clindamycin (48.8% vs. 3.1%), vancomycin (34.7% vs. 3.3%), gentamicin (24% vs. 2.8%) and fluoroquinolones (6.8% vs. 1.3%).

“We hope our findings spark reconsideration of the language about penicillin allergy testing in the national guidelines,” Erica Shenoy, MD, PhD, an assistant physician at Massachusetts General Hospital, said in the release. “In the meantime, I would recommend that any patients with a history of allergy to penicillin or to cephalosporins — the antibiotic class that includes cefazolin — who are scheduled for surgery to ask their doctor whether an antibiotic would be needed and, if so, discuss a referral for an allergy evaluation in advance to increase their chances of getting the most effective antibiotic.” – by Stephanie Viguers


Blumenthal KG, et al. Abstract 2194. Presented at: IDWeek; Oct. 4-8, 2017; San Diego.

Blumenthal KG, et al. Clin Infect Dis. 2017;doi:10.1093/cid/cix794.

Disclosures: The authors report no relevant financial disclosures.