Differences in the susceptibility of Streptococcus pyogenes to rokitamycin and erythromycin A revealed by morphostructural atomic force microscopy

Area of Science:

• Microbiology
• Microscopy
• Pharmacology

Background:

• Streptococcus pyogenes is a significant human pathogen.
• Macrolide antibiotics like erythromycin A and rokitamycin are used to treat S. pyogenes infections.
• Understanding the morphological effects of these antibiotics is crucial for treatment efficacy.

Purpose of the Study:

• To investigate the differential effects of erythromycin A and rokitamycin on the M phenotype of Streptococcus pyogenes.
• To utilize atomic force microscopy (AFM) for high-resolution morphological analysis.

Main Methods:

• Atomic Force Microscopy (AFM) was employed to scan and sense the topography of S. pyogenes.
• Bacteria were incubated with erythromycin A (32 mg/L) and rokitamycin (2 mg/L) for 2, 4, and 6 hours.
• Morphological changes were analyzed by comparing AFM images taken at different time points.

Main Results:

• Erythromycin A did not interfere with the M phenotype of S. pyogenes, even at high concentrations.
• Rokitamycin demonstrated a progressive action, leading to abnormally enlarged cells.
• Rokitamycin also caused loosening of the bacterial chain structure and the formation of clusters.

Conclusions:

• Rokitamycin is effective in disrupting the M phenotype of S. pyogenes, inducing significant morphological alterations.
• Erythromycin A lacks efficacy against this specific phenotype of S. pyogenes.
• AFM is a valuable tool for visualizing antibiotic-induced bacterial morphological changes at high resolution.