An electronmicroscope study of glycopeptide antibiotic-resistant strains of Staphylococcus epidermidis

Area of Science:

• Microbiology
• Cell Biology
• Infectious Diseases

Background:

• Staphylococcus epidermidis is a common cause of nosocomial infections.
• Glycopeptide antibiotics like vancomycin are crucial for treating resistant bacterial infections.
• Understanding the mechanisms of glycopeptide resistance in S. epidermidis is essential for effective treatment.

Purpose of the Study:

• To investigate the ultrastructural changes in glycopeptide-resistant Staphylococcus epidermidis strains.
• To elucidate the effects of sub-inhibitory concentrations of vancomycin and teicoplanin on resistant S. epidermidis.

Main Methods:

• Ultra-thin section transmission electron microscopy was used to examine bacterial cell wall and cytoplasmic structures.
• Resistant and control strains of Staphylococcus epidermidis were cultured and exposed to sub-minimum inhibitory concentrations (sub-MIC) of vancomycin and teicoplanin.

Main Results:

• Two resistant strains showed abnormally thick cell walls, suggesting increased glycopeptide binding sites.
• A third resistant strain exhibited a thickened, irregular cell wall and autolysis, indicating abnormal cell wall synthesis.
• Sub-MIC vancomycin and teicoplanin induced cytoplasmic changes, including intracellular lamellae and mesosome-like structures, in resistant strains.
• Teicoplanin exposure also led to filamentous forms, extracellular material, abnormal septation, and a double-layered cell wall in some resistant bacteria.

Conclusions:

• Glycopeptide resistance in Staphylococcus epidermidis may be associated with altered cell wall synthesis and structure.
• Vancomycin and teicoplanin can induce distinct ultrastructural changes within the cytoplasm and cell envelope of resistant S. epidermidis.
• These findings provide insights into the morphological adaptations and cellular responses contributing to glycopeptide resistance in this opportunistic pathogen.