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Updated: May 14, 2026

Development and Assessment of Intracellular Infection Models for Staphylococcus aureus
Published on: January 17, 2025
Thickening of the cell wall in macrolide-resistant Staphylococcus aureus
Yukiyoshi Hyo1, Sakuo Yamada, Kenji Fukutsuji
1Department of Otolaryngology, Kawasaki Medical School, 577 Matsusima, Kurasiki, Okayama, 701-0192, Japan, yuki-hyo@med.kawasaki-m.ac.jp.
Abstract:
Macrolides are widely used at low dosage for long-term therapy of chronic sinusitis. Twenty clinical macrolide-resistant Staphylococcus aureus strains were morphologically compared with 10 clinical macrolide-sensitive strains. PCR amplification was performed to determine the presence of four known macrolide resistance genes. Transmission electron microscopy revealed significantly thicker cell walls in clinical macrolide-resistant strains. Even though the ultrastructural characteristics were shared by all macrolide-resistant strains, they were not associated with the presence or absence of the known macrolide-resistance genes. We also demonstrated that macrolide-resistant mutant strains derived in vitro from a macrolide-sensitive parent strain had thickened cell walls and did not harbor the known macrolide-resistance genes. These results, therefore, revealed that macrolide-resistant S. aureus strains have thickened cell walls as a common ultrastructural characteristic and that cell wall thickening is likely mediated by an unknown gene which is unrelated to any known macrolide resistance gene.
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