Increase in imported mupirocin-resistant Staphylococcus aureus from the tropics and subtropics: trends in Berlin from 2018 to 2025

Abstract

Background Mupirocin resistance in Staphylococcus (S.) aureus (Mup-RSA) is emerging and may lead to S. aureus decolonisation failure. Our aim was to assess temporal trends in mupirocin-resistant S. aureus (Mup-RSA) and methicillin-resistant S. aureus (MRSA) among S. aureus –positive patients presenting to the Tropical Medicine outpatient Department, also including the Dermatology Department and the overall university hospital for context. Methods We calculated annual percentages of Mup-RSA and MRSA among S. aureus –positive patients and modelled temporal trends using Poisson or negative binomial regression, estimating incidence rate ratios (IRR). Results From January 1, 2018, to June 30, 2025, Mup-RSA was detected in 3.1% (24/782) of patients with S. aureus at the Tropical Medicine Department, 1.1% (23/2030) at the Dermatology, and 0.5% (142/28,122) at the hospital overall. The rate of Mup-RSA among S. aureus -positive patients increased over time at the Tropical Medicine (IRR, 1.64; 95% CI, 1.3 – 2.06, p < 0.01 ), and at the Dermatology (IRR, 1.37; 95% CI, 1.12 – 1.67, p < 0.01 ), but not at the hospital overall. MRSA did not increase significantly over time in either setting. MRSA in Mup-RSA was found in 4.2% (1/24), 4.3% (1/23), and 22.5% (32/142), respectively. Conclusion Mup-RSA proportions are low overall, but have increased substantially in Tropical Medicine, with modest increases in Dermatology. Clinicians should be aware of both the emergence of Mup-RSA and the availability of alternative topical agents for decolonisation, particularly in contexts where S. aureus could be imported from regions with high Mup-RSA prevalence.