"Gram stain" . "Gram-negative" . "Gram" . "gram-positive" . "staining" . "Gram-positive" . "Gram stain and counter-stain" . . . "Gram staining method" . "gram stain" . "gram" . "Gram-stain" . "gram-indeterminate" . . . "Gram-stained" . "stain" . . "positive" . "gram-negative" . "Gram-staining" . "gram-variable" . "Gram-variable and gram-indeterminate bacteria" . . "gram positive" . "Gram-stain-positive" . . . "Gram stain" .