Talk:E. coli

1) Gram reaction? Gram -

2) Catalase reaction? Catalase +

3) Microscopic appearance? Rod

4) Colony characteristics? Colilert Test+ : yellow & fluoresce

5) Isolation? Fecal coliforms can grow @44.5°C,

 inoculum?
 media?
 conditions?

 ONPG + ß-galactosidase ––> ONP(bright yellow) + G  
 MUG + ß-D-glucuronidase ––> MU(fluoresces @340nm) + G 

Colilert Test
ONPG Ortho-nitro-phenol-ß D-Galactopyronoside ß galactosidase is an enzyme of E. Coli that can cleave the bond between ONP & G in ONPG (this bond is similiar to the bond between Glucose & Galactose) MUG 4-methyl-umbelliferone-ß D-Glucuronide

Escherichia coli 1

1) Natural environment is ... large intestine of mammals

2) Dominant types are.... non pathogenic

3) Serology (# of Serogroups) = O (174), & H (flagellar, 56)

4) How many types are pathogenic.= 5 (3 are of most concern)

5) Ones that are of most concern
Enterotoxigenic E. coli (ETEC) ¹
Enteropathogenic E. coli (EPEC) ²
Enterohemorrhagic E. coli (EHEC)

¹ Major cause of death in 3rd world. Travelers & child diarrhea. Heat labile toxin & heat stable toxin.
² Cause of severe diarrhea in children & travelers.

1) How is O157:H7 different?
does not ferment sorbitol in 24hrs, MUG negative, doesn't grow well at 44-45°C, acid tolerant

2) Properties of EHEC?
>100 known serotypes (O157:H7), hemolytic uremic syndrome (HUS -- 3-5% deathrate), low dose, onset 3-8 days, sm intestine infector