lab demonstration of enteric bacteria

LAB DEMONSTRATION OF ENTERIC BACTERIA

Dr. Amel Yacoubi

STATION 1

On Gram staining: Gram positive cocci in groups (Figure n°1)

On blood agar: beta hemolysis (complete hemolysis) (Figure n°2)

On Mannitol salt agar : fermentation of mannitol (yellow color) (Figure n°3)

Coagulase test: positive (Figure n°4) Organism: Staphylococcus aureus

STAPHYLOCOCCUS AUREUS

(Figure n°1)

(Figure n°2)

(Figure n°3)

(Figure n°4)

STATION 2:

Microscopic : Gram negative rods (Figure n°5)

Culture on Mac conkey agar: Lactose fermenting (LF) colonies (pink

colonies) (Figure n°6) Ex: E.coli

Non Lactose fermenting (NLF) (Figure n°7 ) Ex: Salmonella – Shigella

SALMONELLA – SHIGELLA/ E.COLI

(Figure n°5)

(Figure n°6)

(Figure n°7)

STATION 3:

TCBS agar Use: selective medium of Vibrio cholorae

(Figure n°8 ). Growth: V. cholorae gives yellow colonies

due to fermentation of sucrose. Others vibrios give pale colonies because they not ferment sucrose (Figure n°9 ) .

VIBRIO CHOLORAE

(Figure n°8) (Figure n°9)

BACILLUS ANTHRACIS

Station 4:  Gram positive bacilli showing

endospores (Figure n°10) Ex: Bacillus anthracis

(Figure n°10)

STATION 5:

Gram positive rods with variable staining (Figure n°11 ) Ex: Clostridium perfringens

Culture on Robertson cooked meat: Anaerobic medium used for isolation of Cl. Perfringens and others anaerobic bacteria. The color turned orange due to the

saccharolytic activity of organism (Figure n°12).

CLOSTRIDIUM PERFRINGENS

(Figure n°11)(Figure n°12)

ANAEROBIC CULTURE

Station 6:  

Anaerobic jar (Figure n°13)

(Figure n°13)

Anaerobic Gas Pack