We don't have synonyms for oral method yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are gram method.
(n) :
a staining technique used to classify bacteria; bacteria are stained with gentian violet and then treated with gram's solution; after being decolorized with alcohol and treated with safranine and washed in water, those that retain the gentian violet are gram-positive and those that do not retain it are gram-negative
(n) :
a staining technique used to classify bacteria; bacteria are stained with gentian violet and then treated with gram's solution; after being decolorized with alcohol and treated with safranine and washed in water, those that retain the gentian violet are gram-positive and those that do not retain it are gram-negative