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Updated: Sep 14, 2025
Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
Genomic and Phenotypic Characterization of Mupirocin-resistant Staphylococcus aureus Clinical Isolates
Ariana M Virgillio1,2, Emily A Felton2,3, Jessica K Jackson3
1Division of Infectious Disease and International Medicine, University of South Florida, Tampa, Florida, USA.
Background:
Colonization with Staphylococcus aureus is a risk factor for subsequent infection. Decolonization with the topical antibiotic mupirocin is effective and reduces the risk of subsequent S. aureus infection for both methicillin-sensitive and methicillin-resistant (MRSA) strains but may select for mupirocin-resistant isolates.
Methods:
We characterized oxacillin and mupirocin susceptibility amongst 384 S. aureus strains isolated from clinical samples isolated in 2017-2023 in Tampa, Florida, spanning strains collected before and after the onset of the coronavirus disease 2019 (COVID-19) pandemic. Whole genome sequencing of bacterial isolates was conducted in parallel and correlated with drug susceptibility profiles.
Results:
Mupirocin resistance (MupR) was nearly exclusively present in MRSA strains (103/106, 97.1% of MupR; 103/299, 34.4% of MRSA). Although our hospital protocol for decolonization shifted to povidone iodine in the post-COVID period, the overall prevalence of MupR did not change in pre-COVID and post-COVID samples (28.9% vs 26%). Genotype correlated with antibiotic susceptibility with low-level MupR, linked to mutations in ileS and high-level MupR, linked to the presence of mupA. Genome analysis revealed that most MupR strains fell into 3 sequence types (ST) falling into 2 major clonal complexes (CC): CC8 ST8 (including community-associated MRSA strains USA300 and USA500), CC5 ST5 (associated with healthcare-associated MRSA such as USA100), and CC5 ST3390. ST3390 isolates had the highest prevalence of MupR (30/36 83%; high-level MupR 20/36 55.6%; low-level MupR 10/36 27.8%).
Conclusions:
Mupirocin resistance was prevalent in our hospital MRSA strains. We also found evidence for emergence and persistence of ST3390 MRSA-MupR strains in Florida.
Insights
Mupirocin resistance is common in methicillin-resistant Staphylococcus aureus (MRSA) in Florida. Despite changes in decolonization protocols, resistance rates remain stable, with specific sequence types showing high prevalence.
Area of Science:
- Microbiology
- Infectious Diseases
- Genomics
Background:
- Staphylococcus aureus colonization increases infection risk.
- Mupirocin decolonization is effective but can select for resistant strains.
- Methicillin-resistant S. aureus (MRSA) poses a significant public health threat.
Purpose of the Study:
- To characterize oxacillin and mupirocin susceptibility in S. aureus strains.
- To investigate the impact of the COVID-19 pandemic on antimicrobial resistance patterns.
- To correlate genotypic data with antibiotic susceptibility profiles.
Main Methods:
- Analysis of 384 S. aureus clinical isolates from Tampa, Florida (2017-2023).
- Whole genome sequencing of isolates.
- Correlation of genotypic data with oxacillin and mupirocin susceptibility testing.
Main Results:
- Mupirocin resistance was prevalent, primarily in MRSA strains (97.1%).
- Mupirocin resistance prevalence remained consistent before and after the COVID-19 pandemic (28.9% vs. 26%).
- Specific sequence types, particularly ST3390, showed high rates of mupirocin resistance.
Conclusions:
- Mupirocin resistance is a significant issue in hospital-associated MRSA.
- Emergence and persistence of ST3390 MRSA strains with mupirocin resistance were observed in Florida.
- Genomic analysis is crucial for understanding resistance mechanisms and epidemiology.
