Enteric Gram-negative Bacteria Pt 1

Question 1

Medical importance of enterobacteriaceae

Answer 1

• indicator of fecal pollution of water
• responsible for 30% noscomical infections
• easy to be genetically studied
• resistant to antibiotics (hard to treat)

Question 2

Endotoxin components are

Answer 2

Lipid A and O polysaccharide

(HIGHLY POTENT)

Question 3

2 types of non motile enterobacteriaceae

Answer 3

Klebsiella & shigella

Question 4

Enterobacteriaceae

Answer 4

• gram negative
• medium sized rods
• peritrichate arranged flagella if motile
• facultative
• non spore forming
• resistant to acid/bile
• ferment glucose

Question 5

Lactose fermenters on macconkey agar

Answer 5

• pink color
• E. coli, Klebsiella, enterobacter

Question 6

Non-fermenters on Macconkey agar

Answer 6

• yellow color
• Salmonella & shigella

Question 7

Macconkey agar suppresses

Answer 7

• suppresses gram +ve organisms w/ bile salt or bacteriostatic dye

Question 8

Triple Sugar Iron agar (TSI)

Answer 8

Tests for: carb fermentation, gas prod. , hydrogen sulfide prod.

Question 9

In TSI, cracking is caused by

Answer 9

Gas prod

Question 10

In TSI, red slants mean

Answer 10

Only glucose fermented

(Peptones present)

Question 11

In TSI, blackness is caused by

Answer 11

H2S prod.

Question 12

In TSI, fully yellow tube means

Answer 12

All 3 sugars fermented

Question 13

In TSI, yellow and red coloring mean what

Answer 13

Yellow: acid

Red: alkalinic

Question 14

Acidic slant & butt, gas +, H2S - produce

Answer 14

E. coli, enterobacter, Klebsiella

Question 15

Alkaline slant, acid butt, gas & H2S - produce

Answer 15

Shigella, yersinia, morganella

Question 16

Alkaline slant, acid butt, gas & H2S + prod

Answer 16

Salmonella and proteus

Question 17

Major pathogens of animals

Answer 17

Salmonella, E. coli, & 3 yersinia species

Question 18

Opportunistic pathogens

Answer 18

• occasionally cause illness
• Klebsiella, enteribacter, proteus, edwardsiella, citrobacter, morganella, shigella

Question 19

What’s the genus of e-coli?

Answer 19

Escherichia

Question 20

Escherichia

Answer 20

• ferment lactose
• 165 O antigens
• 50 H antigens
• 90 K antigens

Question 21

O antigens

Answer 21

Lipopolysaccharide

Question 22

H antigens

Answer 22

Flagella

Question 23

K Antigens

Answer 23

Capsular antigens

Question 24

E. coli

Answer 24

• naturally found in lg. intestines & lower small intestines
• excreted in feces, survive in fecal particles, dust, and water for wks to mos
• presence in H2O= pollution

Question 25

Capsules

Answer 25

Protect invasive E. coli from complement cascade & anti-phagocytic

Question 26

Adhesins

Answer 26

Mediate adherence to glycoproteins in GIT

Question 27

Cell wall

Answer 27

Endotoxins prevent MAC complement attachment

Question 28

Enterotoxins

Answer 28

• prod inside cell & released
• kills in 2hrs
• affect cyclic nucleotide activity in cell; dereg. water & electrolytes