There is a correlation for documented penicillin allergy
with increased risk of methicillin-resistant Staphylococcus aureus (MRSA)
and Clostridium difficile, which is mediated by increased use of β-lactam
alternative antibiotics, according to a study published online in the BMJ.

Kimberly G. Blumenthal, MD, from Massachusetts General
Hospital in Boston, and colleagues conducted a population-based matched cohort
study to examine the correlation between penicillin allergy and development of
MRSA and C. difficile. Data were included for 301 399 adults without
previous MRSA or C. difficile: 64 141 with a penicillin allergy and 237 258
age-, sex-, and study-entry-time-matched comparators.

The researchers found that during a mean six years of
follow-up, 1365 adults developed MRSA (442 with penicillin allergy) and 1688
developed C. difficile (442 with penicillin allergy). The adjusted
hazard ratio for MRSA and for C. difficile was 1.69 and 1.26,
respectively, among patients with penicillin allergy. Also among patients with
penicillin allergy, the adjusted incidence rate ratios for antibiotic use were
4.15, 3.89, and 2.1 for macrolides, clindamycin, and fluoroquinolones,
respectively. Increased use of β-lactam alternative antibiotics accounted for
55% and 35% of the increased risk of MRSA and C. difficile, respectively.

“Systematically addressing penicillin allergies may be
an important public health strategy to reduce the incidence of MRSA and C.
difficile among patients with a penicillin allergy label,” the
authors write.


Reference: Blumenthal
KG, et al. Risk of methicillin resistant Staphylococcus aureus and Clostridium
difficile in patients with a documented penicillin allergy: population
based matched cohort study. BMJ 2018; 361.
Published 28 June 2018.