Antibiotic Prescribing Practices amongst Internists in Penicillin Allergic Patients

Rationale: Approximately 10% of patients report a history of penicillin (PCN) allergy. In cases of antibiotic prescribing, labeled PCN-allergic patients often receive non-beta-lactam antibiotics, such as quinolones, vancomycin, cephalasporins and macrolides to avoid allergic reactions. These alternatives maybe less effective, more toxic (aminoglycosides), more expensive and broader spectrum agents are often associated with increased risk of c-difficile diarrhea (clindamycin, floroquinolones) as well. We sought to determine the prescribing patterns of internists in the outpatient setting in PCN-allergic labeled patients. 

Methods: We performed a three-month retrospective, IRB approved matched cohort study of patients with and without a documented PCN allergy in our Internal Medicine (IM) clinic. We recorded the prescribing patterns of IM physicians for patients with a history of PCN allergy (cases). This was compared to the antibiotic selection in sex-matched, age-matched control subjects without a history of PCN allergy (controls).

Results: PCN allergy was documented in 518 charts. Macrolides and quinolones were the most common class of antibiotics prescribed in both groups. Macrolides were given to 260(50.2%) cases and 112(21.6%) controls (p=0.696). Floroquinolones were given to 150(29%) cases and 109(21%) controls (p=0.803). There were only 10(1.9%) cases prescribed cephalasporins compared to 53(10.2%) of controls (p=0.451). Ceftriaxone and vancomycin were not prescribed in either group.

Conclusions: In our population, we found no evidence of a difference in the antibiotic prescription pattern amongst internists in patients with and without PCN allergy. Further evaluation in larger PCN allergic populations and amongst other specialties would be helpful to validate these findings.