Bad bugs – not just a problem in penicillin allergic patients

Reviewed by: Cynthia T. Nguyen, PharmD, University of Chicago Medicine

Several studies have described increased rates of MRSA, VRE and C. difficile colonization and infection among patients with penicillin allergies. However, the prevalence of these organisms among patients with any antibiotic allergy is less known. In a single-center retrospective cohort study, Lam and colleagues observed a higher rate of MRSA colonization among patients with any antibiotic allergy compared to those without an antibiotic allergy (8.3% versus 4.7%, p=0.025). This difference was driven by patients with allergies to tetracycline and glyco/lipopeptides. No difference in VRE colonization was observed (36.2% versus 46.9%, p=0.10). Patients colonized with MRSA and VRE also had a greater number of hospital admissions and total hospital days in the preceding year, which may have contributed to these findings. Additional limitations to consider include the lack of universal and standardized MRSA and VRE screening processes for patient inclusion and the lack of prior antibiotic use and other confounding data commonly associated with colonization with resistant pathogens.


Lam W, Staicu ML, Conn KM, Ramsey AC. Is there a higher prevalence of methicillin-resistant Staphylococcus aureus (MRSA) or vancomycin-resistant Enterococcus (VRE) colonization in patients with antibiotic allergy labels?. Am J Infect Control. 2020;48(6):663-667. doi:10.1016/j.ajic.2019.09.021 

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