Electron microscopy revealed that Streptococcus mitis ATCC 903 bound g
old probes conjugated with goat IgG by non-immune mechanisms. Only a f
ew of the cells and the cell wall fragments could bind IgG, in contras
t to Staphylococcus aureus and Streptococcus group G which showed a mo
re homogenous binding to nearly all cells or cell wall fragments.