Antibiotic Prescribing Patterns for Patients With and Without Penicillin Allergy

Penicillin allergy isn’t all that uncommon. What do physicians do when a patient presents with the sensitivity? In a presentation at the annual meeting of the American Academy of Allergy, Asthma, and Immunology (AAAAI 2017) in Atlanta, Sharzad J. Alagheband, MD, explained study results analyzing prescribing practices for people who do and do not have the allergy.

Although about 10% of people in the United States report having an allergic reaction to penicillin at some point, only 1% are truly allergic to the drug, according to the US Centers for Disease Control and Prevention (CDC). Of people who have a confirmed diagnosis of penicillin allergy, 50% lose their sensitivity by five years and 80% by 10 years.

Patients labeled with the allergy are often given non-beta-lactam antibiotics as a supplant. However, these drugs¾such as quinolones, vancomycin, cephalosporins, and macrolides¾may be less effective and more expensive. In addition, aminoglycosides, an antibiotic alternative deemed safe for those allergic to penicillin, can cause nephrotoxicity.

There is a considerable risk of morbidity for patients carrying a penicillin allergy label, Alagheband explained. For patients with this allergy label in an inpatient hospital setting, their risk increases for vancomycin-resistant enterococci (VRE) (30%), Clostridium difficile (C. difficile) (23%), and methicillin-resistant Staphylococcus aureus (MRSA) (14%). Outpatient data, however, is limited.

People carrying the penicillin allergy label need to be appropriately evaluated in order to cut down on the use of broad-spectrum antibiotics.

Alagheband and colleagues conducted a three-month retrospective study to determine internists’ prescribing patterns for patients with a penicillin allergy in an outpatient setting. Patients with a penicillin allergy were matched for sex and age to controls without a history of the allergy.

A total of 518 patient charts documented a penicillin allergy. Patients reported different types of penicillin reactions:

• Immediate hypersensitivity: 344 patients (66.4%)
• Unknown: 163 patients (31.5%)
• Other: nine patients (1.7%)
• Delayed hypersensitivity: two patients (0.4%)

Among patients with and without the allergy, macrolides and quinolones were the most commonly prescribed types of antibiotics.

• Macrolides: 260 penicillin-allergic patients (50.2%) and 112 controls (21.8%)
• Floroquinolones: 150 penicillin-allergic patients (29%) and 109 controls (21%)
• Cephalasporins: 10 pencillin-allergic patients (1.9%) and 53 controls (10.2%)

Neither group received ceftriaxone and vancomycin.

“In our population, when comparing outpatient antibiotic prescription patterns, the antibiotics prescribed were statistically different” Alagheband said.

The types of infections treated were not different between the groups. But compared to non-penicillin labeled patients, people with the label received less cephalasporins and more macrolides, quinolones, and tetracyclines.

One worrisome takeaway was that none of the patients’ primary care physicians (PCPs) referred them to an allergist when they indicated they had a penicillin allergy.

When one of the audience members asked Alagheband how to encourage doctors to refer their patients to allergists, she said that annual physicals create that opportunity. PCPs can use that time to look at the patient’s allergies and refer to a specialist accordingly. For new patients, she suggested that if they report a penicillin allergy, have it followed up with by an allergist.

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