pathotype

Pathotype is a classification term used in microbiology and plant pathology to describe a strain or lineage of a microorganism defined by its pathogenic properties rather than by its genetic sequence alone. A pathotype groups isolates that produce a characteristic set of disease symptoms in a particular host or tissue, or that share a specific repertoire of virulence factors. It is related to, but distinct from, genotype, serotype, or sequence type, which describe genetic or antigenic characteristics rather than disease phenotype.

In humans and animals, several bacterial groups are organized into pathotypes to reflect their disease-causing profiles. Escherichia coli, for example, includes enteropathogenic (EPEC), enterotoxigenic (ETEC), enterohemorrhagic (EHEC), enteroaggregative (EAEC), and enteroinvasive (EIEC) pathotypes, each associated with distinct clinical syndromes and virulence determinants. Other pathogens are similarly classified according to host range or tissue tropism, and pathotype designations guide diagnostics, surveillance, and treatment considerations.

In plant pathology, pathotypes describe strains that differ in virulence on certain host species or cultivars. For many plant pathogens, the term is closely related to, or sometimes used interchangeably with, pathovar, which denotes host range. Pathotype testing often relies on pathogenicity assays and differential host sets to map virulence patterns and monitor the emergence of new variants.

Limitations include that pathotype definitions can be fluid, as horizontal gene transfer, host adaptation, or environmental conditions can alter virulence profiles.