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Updated: Jun 12, 2025
Visualization of Bacterial Resistance using Fluorescent Antibiotic Probes
Published on: March 2, 2020
Synthetic lincosamides iboxamycin and cresomycin are active against ocular multidrug-resistant methicillin-resistant
Camille André1, Kelvin J Y Wu2, Andrew G Myers2
1Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston MA, USA.
Objective:
Antimicrobial resistance is a global pandemic that poses a major threat to vision health as ocular bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA), are becoming increasingly resistant to first-line therapies. Here we evaluated the antimicrobial activity of new synthetic lincosamides in comparison to currently used antibiotics against clinical ocular MRSA isolates.
Methods:
Antimicrobial susceptibility testing was performed by broth microdilution for two novel synthetic lincosamides (iboxamycin and cresomycin) and eight comparator antibiotics against a collection of 50 genomically characterised ocular MRSA isolates, including isolates harbouring erm genes (n = 25).
Results:
Both drugs were active against widespread MRSA clonal complexes CC8 and CC5. The MIC50 and MIC90 of iboxamycin were 0.06 and 2 mg/L, respectively. Cresomycin (MIC50 = 0.06 mg/L) also displayed good activity with an in vitro potency four-fold higher (MIC90 = 0.5 mg/L) than iboxamycin. In isolates harbouring erm genes, MIC90 were >16, 2, and 0.5 mg/L for clindamycin, iboxamycin, and cresomycin, respectively. The in vitro potencies of iboxamycin and cresomycin were similar or higher than that of comparator agents and were not impacted by multidrug-resistance phenotypes or by the presence of erm genes when compared with clindamycin.
Conclusions:
Our results demonstrate that iboxamycin and cresomycin display potent in vitro activity against ocular MRSA isolates, including multidrug-resistant isolates harbouring erm genes.
