Just a few points to consider!! #679s

1. ESCHERICHIA COLI
BIOCHEMISTRY

2. INTRODUCTION
• ESCHERICHIA COLI (COMMONLY ABBREVIATED E. COLI) IS A GRAM-NEGATIVE, ROD-SHAPED
BACTERIUM THAT IS COMMONLY FOUND IN THE LOWER INTESTINE OF WARM-BLOODED
ORGANISMS.
• ENTERIC E. COLI (EC) ARE CLASSIFIED ON THE BASIS OF SEROLOGICAL CHARACTERISTICS AND
VIRULENCE PROPERTIES:
• ENTEROTOXIGENIC E. COLI (ETEC)
• ENTEROPATHOGENIC E. COLI (EPEC)
• ENTEROINVASIVE E. COLI (EIEC)
• ENTEROHEMORRHAGIC E. COLI (EHEC)
• ENTEROAGGREGATIVE E. COLI (EAEC)

3. MACCONKEY AGAR
• RED/PINK LACTOSE-POSITIVE COLONIES.
• LACTOSE IF FERMENTED RESULTING IN PRODUCTION OF ACID; THIS ACID CHANGES THE COLOR OF
INDICATOR FROM NEUTRAL RED TO PINK.
• COLONIES PRODUCED ARE PINK TO RED, FLAT, DRY, & 2-3MM IN DIAMETER.

4. BLOOD AGAR
• COLONIES ARE WITHOUT HEMOLYSIS (GAMMA_HEMOLYSIS), BUT MANY STRAINS
ISOLATED FROM INFECTIONS SHOW BETA-HEMOLYTIC.
• COLONIES ARE SMOOTH, DULL GRAY, & 2-3MM IN DIAMETER.

5. EXTRA POINTS
• IT MOSTLY INVADES THE GASTROINTESTINAL SYSTEM (SPECIFICALLY THE
COLON) AND URINARY TRACT.