title: Thickening of the cell wall in macrolide-resistant Staphylococcus aureus.
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.
authors: Department of Otolaryngology, Kawasaki Medical School, 577 Matsusima, Kurasiki, Okayama, 701-0192, Japan, yuki-hyo@med.kawasaki-m.ac.jp.
authors: Yukiyoshi
authors: Y
authors: Hyo
authors: Sakuo
authors: S
authors: Yamada
authors: Kenji
authors: K
authors: Fukutsuji
authors: Tamotsu
authors: T
authors: Harada
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D002473:Cell Wall / Q000648:ultrastructure*; D018942:Macrolides / Q000494:pharmacology*; D008780:Methyltransferases / Q000235:genetics; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics / Q000648:ultrastructure*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D018942:Macrolides; D008780:Methyltransferases; C431709:ErmA protein, Bacteria