E. Coli

Question 1

What does E. Coli look like under the microscope?

Answer 1

Gram negative rods, found in GI tract of humans/animals.

Question 2

What can E. Coli cause?

Answer 2

UTI, diarrhea, neonatal sepsis, intra-abdominal infections, nosocomial infections

Question 3

How can E. coli cause infections if its a normal gut component?

Answer 3

If barriers are disrupted, or if virulence factors are acquired.

Question 4

What happens when E. coli is plated w/lactose?

Answer 4

On a MacConkey plate, E coli changes the pH and causes a color change. Lactose is fermented.

Question 5

O Antigen

Answer 5

LPS

Question 6

H Antigen

Answer 6

Flagella

Question 7

K Antigen

Answer 7

Capsule

Question 8

Lower UTIs and symptoms

Answer 8

Cystitis (bladder), uretritis (urethra), dysuria and frequency.

Question 9

Upper UTI and symptoms

Answer 9

Pyelonephritis, fever, flank pain, costovertebral angle tenderness, dysuria and frequency.

Question 10

Most common cause of UTI?

Answer 10

E. coli.

Question 11

What is the function of p-pili in E. coli?

Answer 11

Adhere to urinary epithelium. No P-pili, will flow out with urine.

Question 12

Function of type 1 pili in E. coli?

Answer 12

Adhere to perineum.

Question 13

How is pyelonephritis treated?

Answer 13

W/ ciprofloxacin or ceftriaxone (all IV)

Question 14

How is cystitis/urethritis treated?

Answer 14

W/ ciprofloxacin or ceftriaxone (oral), or TMP-SMZ

Question 15

Diarrhea causing strains of E. coli

Answer 15

ETEC (enterotoxigenic)
EPEC (enteropathogenic)
EIEC (enteroinvasive)
EHEC (enterohemorrhagic)
EAEC (enteroaggregative)

Question 16

ETEC and virulence factors

Answer 16

Enterotoxigenic E. coli. Causes travelers diarrhea. Heat labile (AB exotoxin stims AC, cause Na, K secretion) and heat stable (stimulates GC, causes Cl, HCO3 secretion), no invasion. CF Pili cause adhesion. Come from a single plasmid.

Question 17

EPEC and virulence factors

Answer 17

Enteropathogenic E. coli. Causes watery diarrhea in infants. Histologically = attachment/effacement lesion. Type III injection system introduces virulent proteins that trigger cytoskeleton rearrangements.

Question 18

Where do the virulence genes come from for ETEC and EPEC?

Answer 18

ETEC (plasmid)

EPEC (Pathogenicity island [PAI])

Question 19

EAEC

Answer 19

Enteroaggregative E. coli. Causes prolonged watery diarrhea in children. Stacked brick appearance and biofilm.

Question 20

EHEC and sequella

Answer 20

Enterohemorrhagic. Shigatoxin (AB exotoxin that injured enterocytes and causes) Bloody diarrhea without a fever, progresses to hemolytic-uremic syndrome (HUS). Also causes microangiopathic anemia, thrombocytopenia, and renal failure(from shigatoxin). Acquired through raw beef, animal feces consumption, direct contact w/animals.

Question 21

How to diagnose EHEC?

Answer 21

Look for shigatoxin in stool. Plate on sorbitol agar, O157:H7 causes clear colony formation

Question 22

How does EHEC get shigatoxin gene?

Answer 22

From a phage.

Question 23

EIEC

Answer 23

Enteroinvasive. Causes dysentery = small volume, bloody diarrhea, crampy abdominal pain, fever. Focus is in large intestine. Lots of WBC’s in stool. Bacterial invasion.

Question 24

How to fix intraabdominal infections?

Answer 24

Surgery and medicine

Question 25

What part of E. coli is responsible for neonatal sepsis? How to treat?

Answer 25

K1 capsular antigen. Cefotaxime and ampicillin

Question 26

ESBLs

Answer 26

Extended spectrum betalactamases, can inactivate generations 1-3 ceph.

Question 27

KPCs

Answer 27

Klebsiella pneumonia carbapenamases. Dangerous because carbapenems are treatment for ESBLs. Both occur in E. coli.