The rRNA sequence of P. shigelloides has been found to be most similar to Proteus mirabilis, and as a result it is now considered part of the tribe Proteeae within the family Enterobacteriaceae.

P. shigelloides is incapable of surviving in saltwater environments where the concentration of salt is greater than 4% and has been found to tolerate pH ranges between 4.5 and 9.

[9][8] The effects of pH, salinity, temperature, turbidity, and conductivity on concentrations of P. shigelloides in freshwater conditions is not currently understood.

[11] P. shigelloides has been isolated from a wide variety of human clinical specimens including both intestinal (usually feces or rectal swabs) and extra-intestinal.

Although reports have found a link between P. shigelloides and diarrhea or gastroenteritis, research has not yet determined whether this bacteria is always responsible for these conditions.