Colonial variants of proteus species: their growth requirements, biochemical characters and resistance to antibacterial agents.

Stable small-colony variants of Proteus species were isolated and characterised. They differed from typical organisms in their morphology, biochemical properties and drug resistance. They were found most frequently in culture media of low osmolarity. Their growth rate was depressed at high concentrations of salts, which had only a small effect on typical organisms. This may be important in the routine isolation of proteus spp. and in testing of disinfectants.