Thymidine-dependent small-colony variants of Staphylococcus aureus exhibit gross morphological and ultrastructural changes consistent with impaired cell separation.

Thymidine-dependent small-colony variants (SCV) of Staphylococcus aureus exhibited unusual colony morphology with "fried-egg" or pinpoint white colonies on agar plates and pleomorphic cocci as determined by Gram staining. Electron microscopy revealed enlarged cocci with incomplete or multiple cross walls consistent with impaired cell separation. Fried-egg SCV phenotypes could be reversed by thymidine supplementation.