Which organism is frequently confused with Salmonella species?

Citrobacter freudii is frequently confused with Salmonella species due to several characteristics they share in terms of biochemical properties and their ability to be isolated from similar environments, such as the intestines of animals and human fecal matter. Both organisms are members of the family Enterobacteriaceae and can exhibit similar colony morphology on certain media, which can lead to misidentification in laboratory settings.

In addition, both Citrobacter freudii and Salmonella species can produce hydrogen sulfide, which can further complicate differentiation on selective media like triple sugar iron (TSI) agar. They can also share certain pathogenic capabilities, though they generally cause different types of infections. The presence of such similarities contributes to the confusion in their identification and classification, which is especially critical in a clinical microbiology context. This explains why someone might mistakenly identify Citrobacter freudii as a Salmonella species if proper biochemical tests and confirmatory methods are not utilized.