Media for the detection and recognition of the enteropathogen Providencia alcalifaciens in faeces

A medium (PAM: Providencia alcalifaciens medium) is described that enables the presence of the enteropathogen P. alcalifaciens in faeces to be detected with ease and simplicity. This organism is probably the only oxidase-negative organism likely to be present in tetrathionate broth cultures of faeces that is unable to ferment the mannitol, xylose or galactose present in the medium. Thus the red colonies of P. alcalifaciens appeared quite distinct from the lemon-yellow acid-forming colonies of all the other bacteria that ferment one or more of these sugars. Extensive tests showed the medium to be both highly specific and sensitive in detecting P. alcalifaciens. Two additional media are described that enable the identity of presumptive P. alcalifaciens isolates to be confirmed unequivocally and with ease.