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Question 1

Q1: Name any member of Enterobacteriaceae.

Answer 1

Answer: Budvicia / Buttiauxella / Cedecea / Citrobacter / Edwardsiella / Enterobacter / Escherichia / Ewingella / Hafnia / Klebsiella / Kluyvera / Lectercia / Leminorella / Morganella / Obesumbacterium / Pragia / Pantoea / Photorhabdus / Providencia / Rabnella / Salmonella / Serratia / Shigella / Tatumella / Trabulsiella / Xenorhabdus / Yersinia / Yokenella

Question 2

Q2: Which antigen can mask the presence of O antigens?


Answer 2

Answer: K antigens

Question 3

Q3: How must somatic antigen negative - capsular antigen positive organisms be treated to destroy the capsular antigen?


Answer 3

Answer: Heated; suspension is boiled for 15 minutes

Question 4

• Part of the normal GIT microbiota of humans and animals

Answer 4

opportunistic pathogens

Question 5

• Do not readily cause infection but may cause serious extraintestinal infection outside body site like Urinary Tract Infections (UTIs), septicemia, wound infections in healthy individuals, and meningitis in neonates

Answer 5

Opportunistic pathogen

Question 6

Q5: Give examples of opportunistic pathogens.


Answer 6

Citrobacter, E. coli, Enterobacter, Klebsiella, Serratia, Proteus

Question 7

• Not a member of commensal microbiota

Answer 7

true pathogens

Question 8

Where’s the true pathogen acquired

Answer 8

From contaminated food and water

Question 9

Their presence on given samples are always significant

Answer 9

True Pathogen

Question 10

Q7: Give examples of true pathogens.


Answer 10

Answer: Salmonella, Shigella, Yersinia pestis

Question 11

Q8: What macroscopic appearance is assessed on MAC for enterobacteriaceae?


Answer 11

Answer: Growth/no growth - lactose fermenter or not

Question 12

Q9: Which carbohydrate (sugar and alcohol) fermentation patterns are tested?


Answer 12

Answer: Lactose, sucrose, glucose, Mannitol, sorbitol

Question 13

Tests for enterobateriaceae

Answer 13

IMVC , LIA, Motility, ONPG test, Urease, Oxidase, Deaminase, Decarboxylase

Question 14

Assess the ability to ferment glucose, lactose, and sucrose and to produce hydrogen sulphide

Answer 14

TSI

Question 16

Q13: TSI composition?


Answer 16

Answer: 1% lactose, 1% sucrose, 0.1% glucose

Question 17

Q14: pH indicator used in TSI?

Answer 17

Answer: Phenol red

Question 18

TSI ferments what

Answer 18

Lactose , sucrose , glucose

Question 19

Original color of TSI medium

Answer 19

Red

Question 20

Q15: H2S indicator in TSI?


Answer 20

Answer: Ferrous sulfate and sodium thiosulfate

Question 21

Q16: How is H2S detected in TSI?


Answer 21

Answer: Black precipitate in the medium

Question 22

Q17: K/A result in TSI indicates?


Answer 22


Answer: Red Slant / Yellow Butt → Glucose/Dextrose fermentation

Question 24

Q18: A/A result in TSI indicates?


Answer 24

Answer: Yellow Slant / Yellow Butt → Fermentation of dextrose, lactose, and sucrose

Question 25

Q19: K/K result in TSI indicates?


Answer 25

Answer: Red Slant / Red Butt → No Fermentation

Question 26

Q20: Gas production in TSI is indicated by?


Answer 26

Answer: Bubbles or cracks in the agar

Question 27

Ability to deaminate lysine (aerobic, slant) or decarboxylate lysine (anaerobic, butt)

Answer 27

LIA

Question 28

Ability to deaminate lysine

Answer 28

(aerobic, slant)

Question 29

decarboxylate lysine

Answer 29

(anaerobic, butt)

Question 30

Q22: What happens during lysine decarboxylation?


Answer 30

Answer: Cadaverine neutralizes acid, turning butt purple (alkaline)

Question 31

Q23: What indicates lysine decarboxylation?


Answer 31

Answer: Purple slant / Purple butt → K/K

Question 32

Q24: What indicates lysine deamination?


Answer 32

Answer: Red slant → R/A

Question 33

Q25: Negative lysine decarboxylation result?


Answer 33

Answer: Purple slant / Yellow butt (K/A or R/A)

Question 34

Q26: Negative lysine deamination result?


Answer 34

Answer: Slant remains purple (K/K or K/A)

Question 35

Q26: Negative lysine deamination result?


Answer 35

Answer: Slant remains purple (K/K or K/A)

Question 35

Q27: What does K, A, and R mean?


Answer 35

Answer: K → Alkaline, A → Acid, R → Red production (positive for lysine deamination)

Question 36

Q22: What happens during lysine decarboxylation?


Answer 36

Answer: Cadaverine neutralizes acid, turning butt purple (alkaline)

Question 37

Q23: What indicates lysine decarboxylation?


Answer 37

Answer: Purple slant / Purple butt → K/K

Question 38

Q24: What indicates lysine deamination?


Answer 38

Answer: Red slant → R/A

Question 39

Q25: Negative lysine decarboxylation result?


Answer 39

Answer: Purple slant / Yellow butt (K/A or R/A)

Question 40

Q26: Negative lysine deamination result?


Answer 40

Answer: Slant remains purple (K/K or K/A)

Question 41

Q27: What does K, A, and R mean?


Answer 41

Answer: K → Alkaline, A → Acid, R → Red production (positive for lysine deamination)