Proteus, Providencia, and Morganella Group

Proteus, Providencia, and Morganella Group
Members of these genera are agents of urinary tract and other extra intestinal infections. This group deaminate phenylalanine, are motile, grow on potassium cyanide medium (KCN), and ferment xylose. Proteus species and Morganella morganii are urease-positive, while Providencia species usually are urease-negative. The proteus-providencia group ferments lactose very slowly or not at all.

Lab diagnostic tests:
1- Gram stain : G-ve bacilli or coccobacilli.
2- MacConkey agar : Selective & Differential
Selective : -Crystal violet (inhibit G+ve)
-Bile salt (inhibit G-ve other than enterobacteriacea).
Differential: differentiate between lactose fermentor (pink colony) and non fermentor lactose (pale colony).
Indicator neutral red : - yellow in alkaline Ph.
- pink in acid ph.
3- EMB (Eosin Methylen blue) : Selective and Differential
- Selective for enterobacteriaceae *Methylene blue (inhibit G+ve)
-Differential for E.coli (green metallic sheen)
Lactose fermentation lead to alcohol + Eosin that lead to metallic sheen.
4-TSI (Triple Sugar Iron agar):
Contain glucose 1%, sucrose and lactose 10%, phenol red indicator used for sugar fermentation, H2S production.
Result:Yellow………acidic, pinkish……….alkaline, gas………..bubbles if fermentation occur (CO2), FeS………… (Black precipitate).