Difficulties encountered in identification of a nutritionally deficient streptococcus on the basis of its failure to revert to streptococcal morphology.

Difficulties were encountered in the recognition of a nutritionally deficient streptococcus which continued to display aberrant morphologic forms (especially bulbous swellings and filament formation) despite provision of growth factors. With isolates displaying diverse morphologic entities not characteristic of a given species, e.g., Streptobacillus moniliformis or Erysipelothrix rhusiopathiae, nutritionally deficient streptococci should be considered.