Characteristics of Enterobacteriaceae

Question 1

Gram stain

Answer 1

Non–spore-forming gram-negative rods

Question 2

Growth characteristics

Answer 2

Facultative anaerobes

Question 3

Colonies on sheep blood agar

Answer 3

Most are large, dull, gray, nonhemolytic

Question 4

Colonies on MacConkey

Answer 4

Lactose fermenters(pink) and Non–lactose fermenters (colorless)

Question 5

Biochemicals

Answer 5

Ferment glucose
Oxidase neg
Most reduce nitrates to nitrites
Most are catalase pos

Question 6

Characteristics(Hint: There are 6!)

Answer 6

1. Gram negative rods with lack of spores
2. Oxidase Neg
3. Catalase Pos
4. Reduce nitrates to nitrites
5. Facultative anaerobes
6. Ferment glucose

Question 7

Lactose fermenters(C.E.E.K)

Answer 7

Citrobacter

Enterobacter

E.Coli(++–)IMViC

Klebsiella(–++)IMViC

Question 8

Which Klebsiella is indole pos and which one is indole neg?

Answer 8

• K. oxytoca(POS)

- K. pneumoniae(NEG)

Question 9

Non lactose fermenters(M.E.P.P.S.S.S.Y)

Answer 9

Morganella

Edwarsiella

Proteus

Provdencia

Salmonella

Shigella

Serratia

Yersinea

Question 10

Which Proteus spp. is indole pos and which one is indole neg?

Answer 10

• P. vulgaris(POS)

- P. mirabilis(NEG)

Question 11

What Enterobacteriaceae are NOT apart of normal flora?

Answer 11

Salmonella, Shigella, E. coli 0157 and Yersinia

Question 12

What diseases are caused by Enterobacteriaceae?”PMS wound guf”
(Try to remember 6/8)

Answer 12

UTIs

gastroenteritis

food poisoning

wound infections

pneumonia

meningitis

septicemia

peritonitis

P.neumonia
M.eningitis
S.epticemia
Wound infections
G.astroenteritis
U.TI's
F.ood poisening

Question 13

Which organisms are associated with UTI’s?

Answer 13

E.coli(Most common in non-hospitalized patients)

Klebsiella

Proteeae

Citrobacter

Question 14

Which organisms are associated with neonatal meningitis?

Answer 14

Citrobacter

Klebsiella

Question 15

What are the 3 serotyping antigens?”KOH” antigens

Answer 15

Capsule “K” antigen

Cell wall “O” antigen

Flagella “H” antigen

Question 16

Good clues for Enterobacteriacae

Answer 16

gram negative bacilli

growth on MAC

oxidase negative

biochemical ID

Question 17

How do they grow on sheep blood agar?

Answer 17

Most are large, dull, gray, nonhemolytic

Question 18

What is the KES Group (Klebsielleae)?

Answer 18

Klebsiella

Enterobacter

Serratia

Question 19

What is the Proteeae group(PPM group)?

Answer 19

Proteus

Providencia

Morganella

Question 20

Routine media used and colony and characteristics?

Answer 20

• Blood agar (BAP)(mucoid, swarming, cauliflower…)

- MacConkey (MAC) Isolate & differentiate lactose fermenters (pink) and non-lactose fermenters (clear)

Question 21

Selective/Differential Media used, note appearance and what they isolate and differentiate(Hint: There are 6!)

Answer 21

Hektoen (HE) enteric agar(THINK GREEN)

Xylose-Lysine-deoxycholate (XLD) agar(THINK RED)

Salmonella-Shigella (SS) agar(THINK COLORLESS)

Sorbitol MacConkey (SMAC)

Gram negative broth

Selenite broth

Question 22

What are HE, XLD, and SS agar used for?

Answer 22

Isolate & differentiate Salmonella and Shigella

Salmonella produces a black center when grown

Question 23

What is the SMAC agar used for?

Answer 23

Isolate & differentiate E. Coli 0157:H7

E. coli 0157 cannot ferment Sorbitol, will show up colorless

Question 24

What are the 2 broths and what are they used for?

Answer 24

Gram negative broth: Enhance isolation of enteric pathogens

Selenite broth: Inhibits coliform growth