Enter toxin mediated

Pathogenesis of diarrhea by E. coli (Enter toxin mediated)

Diagnose urinary tract infection (UTI) caused by E. coli.

Steps:

1. Specimen:

ð  Clean catch mid-stream urine.

ð  Suprapubic puncture in infants.

2. Microscopic examination:

Wet preparation of centrifuged deposit , it helps in provisional diagnosis.

Finding : Pus cell > 5 per high power field (HPF) is significant to diagnose of UTI.

3. Isolation and identification from culture:

Process:

1. Mix the urine by rotating the container .
2. Using a sterile calibrated wire loops, inoculate a loopful of urine in media like

ð  Blood agar.

ð  Mac-Conkey’s agar media.

3. Incubate the plates aerobically at 37°C for over night.

Colony coutn:

• 10⁵/ ml of Gram –negative bacilli is  significant
• In case of supra-pubic puncture, only one colony of Gram-negative bacilli is significant.

4. Biochemical tests: Identification is also done by standard bio-chemical tests like-

i.KIA medium

Slant           =y²

Butt            =y

Gas             = ±

H₂S            =Negative(-)

ii.MIU medium

Motility      =   +¹

Indole         =    +³

Urease        =(-)