ABSTRACT

The identification of bacterial isolates to the species level, or even to the genus level, is sufficient in many situations. For example, the identification of Shigella species in the stool of a child with bloody diarrhea is sufficient to establish a diagnosis and suggest appropriate therapy. In many cases, how­ ever, bacterial isolates must be grouped at a lower level. Bacterial subtyping is the differentiation of isolates below the species level. Examples of bacte­ rial subtyping include traditional methods such as serotyping, phage typing, biotyping, and antimicrobial resistance typing, and newer methods such as molecular subtyping or DNA fingerprinting. Molecular methods are typ­ ically the most sensitive and do not require any special reagents or skills, and they are thus becoming increasingly popular.