E coli lab types and laboratory diagnosis

5 minute lecture ....
on lab diagnosis of e.coli

1. Learning Objective : List the diarrhogenic Escherichia coli and their lab diagnosis

2. Diarrhoea causing Escherichia coli: Enterotoxigenic Escherichia coli (ETEC ) Enteropathogenic Escherichia coli (EPEC ) Enteroinvassive Escherichia coli (EIEC ) Enterohaemorrhagic Escherichia coli (EHEC ) Enteroagregative Escherichia coli (EAEC )

3. Lab diagnosis Sample collection : Sample must be collected depending upon the site of lesion Urinary tract infection Urine Acute diarrhea F aeces and Rectal swab Wound Pus (in sterile cotton swab) Pyogenic meningitis CSF

4. Microscopy: Gram’s staining Gram negative bacilli and non- sporing rods Background- Pus cells Culture: MacConkey’s agar L actose fermenting, mucoid pink coloured colonies Blood agar Moist non haemolytic creamy white colonies Nutrient agar Colourless , smooth large colonies

5. Biochemical tests: Catalase + ve Oxidase - ve Glucose ( Gas) + ve Lactose ( Acid) + ve Indole + ve MR(Methyl red) + ve VP ( Voges-Proskauer ) - ve Citrate Utilization - ve Urease test - ve H2S production - ve Nitrate reduction + ve Antibiotic Sensitivity test: Disc diffusion method

6. References P Chakrabort A nantanarayan

7. Thank you!

8. Any questions?