(HealthDay News) — Patients with a history of penicillin “allergy,” even though that may be inaccurate, spend more time in the hospital and have a greater risk of acquiring antibiotic-associated infections, according to research published in the Journal of Allergy and Clinical Immunology.

Eric Macy, MD, of the Southern California Permanente Medical Group in San Diego, and Richard Contreras, of the Kaiser Permanente Health Care Program in Pasadena, Calif., conducted a retrospective, matched cohort study involving 51,582 subjects with penicillin “allergy” who were admitted to Kaiser Foundation hospitals in Southern California in 2010–2012. Each subject was matched to two control subjects by age, sex, date of admission, and discharge diagnosis.

The researchers found that patients labeled with penicillin allergy, compared with control subjects, averaged 0.59 more total hospital days (95% confidence interval [CI], 0.47–0.71). Case subjects received treatment with significantly more of each of the following antibiotics: fluoroquinolones, clindamycin, and vancomycin. Compared with control subjects, case subjects experienced more Clostridium difficile infections (23.4%; 95% CI, 15.6–31.7%), methicillin-resistant Staphylococcus aureus infections (14.1%; 95% CI, 7.1–21.6%), and vancomycin-resistant Enterococcus infections (30.1%; 95% CI, 12.5–50.4%).

“A penicillin ‘allergy’ history, although often inaccurate, is not a benign finding at hospital admission,” the authors write.

The Kaiser Permanente Health Care Program and ALK-Abelló funded the study. Both study authors disclosed financial ties to ALK-Abelló.

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