Patients who report having a prior penicillin allergy have been found to have a 50% increased risk of developing a surgical site infection (SSI), according to US researchers.
A study by Massachusetts General Hospital found that surgical patients believed to be allergic to penicillin were significantly more likely to develop infections than those with no documented allergy.
“This study has direct clinical significance”
The differential SSI risk was “attributable to receipt of alternative antimicrobial prophylaxis in the patient population reporting a prior history of penicillin allergy”, said the study authors.
They highlighted that 40% of healthcare-related infections in hospital patients occurred at the site of surgical incisions and that such infections could lead to complications and even death.
Reported penicillin allergies have been associated with increased healthcare-related infections, but no previous study has analysed a potential impact on surgical site infections, said the researchers.
They reviewed the records of almost 8,400 patients who underwent common surgical procedures – hip or knee replacement, hysterectomy, colon surgery and coronary artery bypass – during 2010-14.
Of that total, 922 patients had penicillin allergy noted in their medical record, a proportion similar to that of the general US population.
Overall, 214 patients developed a surgical site infection, which translated into 3.5% of those with documented penicillin allergy and 2.6% of those without.
After adjustment for factors such as age, sex and the type and duration of surgery, the risk of a surgical site infection was found to be 50% higher in patients with a reported penicillin allergy.
The only factor clearly associated with infection risk was the type of antibiotic patients received, highlighted the researchers.
“The 50% increased odds of SSI among patients reporting a penicillin allergy in this cohort was entirely due to the use of beta-lactam alternative perioperative antibiotics,” stated the researchers.
“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 said in the journal Clinical Infectious Diseases.
Further analysis revealed that practically all of the patients in the study could have safely received standard testing for penicillin allergies, suggesting they could have tolerated a beta-lactam antibiotic like cefazolin in order to cut SSI risk.
They noted that, instead of cefazolin, patients with a documented penicillin allergy often received clindamycin, vancomycin and gentamicin, which were known to be less effective against SSIs.
They added vancomycin also requires a longer infusion time than cefazolin, so the increased infection rate could also relate to patients receiving it too close to surgery for full effectiveness.
Patients with reported penicillin allergy at ‘higher SSI risk’
Lead study author Dr Kimberly Blumenthal said: “This study has direct clinical significance.
“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 in these patients,” she said.
Senior study author Dr Erica Shenoy suggested that patients with a history of allergy to penicillin or to cephalosporins should be referred for an allergy evaluation in advance to increase their chances of getting the most effective antibiotic.
Dr Shenoy will be presenting the findings this week at an annual US infection control conference in San Diego. Presentation of the data at the IDWeek 2017 conference will coincide with publication in the journal.