Correlation between a direct Gram stained smear of the specimen and what grows in culture should always be attempted. However, some bacterial organisms may appear differently when viewed in direct clinical specimens versus isolates growing on solid or in liquid culture media. For example, if gram-negative organisms are surrounded by large amounts of cellular material in the direct smear, the cellular material may totally or partially prevent decolorization of the bacteria so that the gram-negative bacteria growing in culture may appear gram-positive or gram-variable on direct smear.
