Morphologic study of Staphylococcus aureus L-form, reverting, and intermediate colonies in situ

Area of Science:

• Microbiology
• Veterinary Science
• Bacterial Pathogenesis

Background:

• Staphylococcus aureus is a significant pathogen in bovine mastitis.
• Understanding bacterial L-forms is crucial for developing effective antibiotic treatments.
• Penicillin-induced L-forms of Staphylococcus aureus present unique morphological characteristics.

Purpose of the Study:

• To characterize the morphology of Staphylococcus aureus L-forms derived from bovine strains.
• To investigate the growth patterns and developmental stages of these L-forms in vitro.
• To establish a basis for identifying similar forms in vivo during chronic bovine mastitis treatment.

Main Methods:

• Bovine Staphylococcus aureus strains were induced into L-forms using penicillin.
• L-forms were cultured on supplemented brain heart infusion agar without antibiotics.
• Morphological analysis was performed using light and electron microscopy on plastic-embedded colonies.

Main Results:

• Observed diverse L-form morphologies, including pleomorphic budding forms and large spherules.
• Identified growth primarily in the agar core, with surface colonies showing progression to spherules.
• Documented reverting forms with cell wall development and intermediate colony forms.

Conclusions:

• Staphylococcus aureus L-forms display varied morphologies and growth patterns in vitro.
• These findings provide a reference for identifying L-forms in vivo during bovine mastitis treatment.
• Further in vivo studies are warranted to correlate these findings with antibiotic efficacy.