Cultural and Biochemical Characteristics of Medically Important Bacteria

Cultural and Biochemical Characteristics of Medically Important Bacteria

Name of Bacteria	Cultural Characteristics
1. Staphylococcus aureus
	Colonies on Mannitol Salt Agar (MSA) Picture Credit: Ms. Samjhana Kapali
	Colonies on Mueller Hinton Agar (MHA)
	Colonies on Blood Agar (BA) Media Picture Credit: Ms. Sanjita Khadka
	Coagulase Test [A] Negative [B] Positive
	A. Positive Control; B Negative Control and C. Test: Positive. Picture Credit: Ms. Samjhana Kapali
2. Salmonella Typhi
	Colonies on Mac-Conkey Agar (MA)
	Colonies on Xylose-Lysine Deoxycholate Agar (XLD) Picture Credit: Mr. Saroj Khadka
	Colonies on Blood Agar (BA) Media Picture Credit: Mr. Saroj Khadka
	Biochemical Set of Salmonella Typhi. From Left to Right: A: Oxidative Test: Positive; B: Fermentative Test: Positive; C: Indole: Negative; D: Methyl Red: Positive; E: Voges Proskauer: Negative; F: Citrate Test: Negative; G: Triple Sugar Iron: Alkaline/Acid, Hydrogen Sulphide Positive, Gas Production Negative; H: Urea Hydrolysis: Negative.

3.Vibrio cholerae

Colonies on Thiosulfate-Citrate-Bile salts-Sucrose Agar (TCBS)

4.Pseudomonas aeruginosa

Green colonies on Mueller Hinton Agar (MHA)

Biochemical Set of Pseudomonas aeruginosa
From Left to Right:
1: Indole Test: Negative; Motile
2: Methyl Red: Negative;
3: Voges Proskauer: Negative;
4: Urea Hydrolysis: Negative.
5: Citrate Test: Positive;
6: Triple Sugar Iron: Alkaline/Alkaline, Hydrogen Sulphide Negative, Gas Production Negative
7: Oxidative Test: Positive; However, due to pH of the media, the result here is diverted.
8: Fermentative: Negative;


Picture Credit: Ms. Shrijana Bhandari 5.Escherichia coli

Cysteine Lactose Electrolyte Deficient Medium(CLED)

Biochemical Reaction from Left to Right of Anaerogenic E coli.
[1️] TSI: R/Y (A/A), H2S -ve, Gas -
[2️] Citrate: Negative
[3️] Urease: Negative (actually is varibale +ve)
[4️] SIM: Indole +ve, Motility +ve


Picture Credit: Mr. Saroj Khadka

Characteristic Green Metallic Sheen on Eosine Methylene Blue (EMB) Agar Media


Picture Credit: Mr. Saroj Khadka

6.Salmonella Paratyphi A

Colonies on Xylose-Lysine Deoxycholate Agar (XLD)

Biochemical Set of Salmonella Paratyphi A.
From Left to Right:
A: Oxidative Test: Positive;
B: Fermentative Test: Positive;
C: Indole: Negative;
D: Methyl Red: Positive;
E: Voges Proskauer: Negative;
F: Citrate Test: Negative;
G: Triple Sugar Iron: Alkaline/Acid, Hydrogen Sulphide Negative, Gas Production Positive;
H: Urea Hydrolysis: Negative.
7.Klebsiella pneumomiae

Colonies on Mac-Conkey Media
Picture Credit: Mr. Saroj Khadka

Colonies on CLED

Biochemical Set of Klebsiella pneumoniae
From Left to Right:
A: Indole: Negative;
B: Urea Hydrolysis: Positive;
C: Citrate Test: Positive;
D: Triple Sugar Iron: Acid/Acid, Hydrogen Sulphide Negative, Gas Production Positive.


Picture Credit: Mr. Saroj Khadka 8.Enterobacter cloacae

Biochemical Reaction from Left to Right
[1️] TSI: Y/Y (A/A), H2S -ve, Gas +
[2️] Citrate: Positive
[3️] Urease: Negative (actually is varibale +ve)
[4️] SIM: Indole -ve, Motility +ve


Picture Credit: Mr. Saroj Khadka

9.Acenitobater spp.

Biochemical reaction
From Right to Left
[1] Indole: Negative, Non-motile
[2] TSI: Red/Red (i.e. lac/suc non-fermneter), H₂S negative, Gas negative
[3] Urease: Negative
[4] Citrate: Positive


Picture Credit: Mr. Saroj Khadka

10. Proteus mirabilis

Bichemical Reactions (from left to right)
[1] Citrate: Negative (Although most strains of P. mirabilis are citrate +ve, some are citrate -ve.)
[2] TSI: Red/Yellow i.e. lactose/sucrose non-fermneter, H₂S production, Gas production
[3] Urease: Positive
[4] Indole: Negative, Motile

Picture Credit: Mr. Saroj Khadka