gram negative lecture 2

Question 1

virulence factors of v. cholerae

Answer 1

• flagella
• pili to adhere to mucosal tissue
• cholera toxin- phage encoded

Question 2

2 types of E. coli that cause secretory diarrhea

Answer 2

ETEC and EPEC

Question 3

dysentery-like E. coli

Answer 3

EHEC

Question 4

type of E. coli that causes urinary tract infections

Answer 4

EPEC

Question 5

ETEC has a ____ infectious dose and ____ on fimbrae help to adhere to mucosal tissue

Answer 5

large; colonization factor antigens (cfa)

Question 6

ETEC produces 2 toxins that are responsible for the disease:

Answer 6

heat-labile toxin (LT)

heat-stable toxin (ST)

Question 7

in vibrio species, cholera toxin causes transfer of ____ from _____ to activate ___

Answer 7

ADP; NAD; Gs

Question 8

in ETEC, ____ activates AC and ST (heat stabile toxin) activates ____

Answer 8

LT (heat labile toxin); GC

Question 9

treatment for secretory diarrhea

Answer 9

• oral rehydration- mix of sugar and salt

- antibiotics can help shorten duration or reduce severity

Question 10

____ used for vibrio infections

Answer 10

tetracyclines

Question 11

____ for ETEC

Answer 11

2nd generation fluoroquinolones

Question 12

EPEC is prevalent in ____ and causes _____

Answer 12

newborns; noninflammatory secretory diarrhea

Question 13

EPEC is located in ____ and requires a ____ infectious dose; absence of traditional ____

Answer 13

distal small intestine; large; exotoxins

Question 14

EPEC displays a characteristic ____ (aka an attaching and effacing lesion)

Answer 14

adherence pattern

Question 15

stage 1 of intimate adherence by EPEC and EHEC

Answer 15

bundle-forming pili (bfp) assist in adherence from relative long distance

Question 16

stage 2 of intimage adherence

Answer 16

syringe-like secretion system (called type III secretion) injects Tir into host cell

Question 17

for EPEC, there is no ____ production; malabsorption due to ____ and disruptions of _____ cause diarrhea

Answer 17

toxin; microvilli disruptions; epithelial tight junctions

Question 18

EHEC has set of ____ genes (called eae genes), so it produces an ____; also produces toxin that can lead to _____ (which is much more serious)

Answer 18

EPEC; attaching effacing lesion; hemolytic uremic syndrome

Question 19

____ is the most common EHEC; ___ are the primary reservoir; causes an _____ (gastroenteritis)

Answer 19

E. coli (O157:H7); cattle; attaching effacing lesion

Question 20

EHEC produces a ____-like toxin that causes ____ and _____

Answer 20

shiga; hemorrhagic colitis; hemolytic uremic syndrome

Question 21

diagnosis of EHEC

Answer 21

• frankly bloody stool, edema of ascending colon
• cannot ferment sorbitol, usually
• detection of shiga-like toxins

Question 22

treatment for EHEC

Answer 22

• no antibiotics, supportive therapy
• rehydrate if necessary
• dialysis if hemolytic uremic syndrome (HUS) pending

Question 23

natural defenses found in the urinary system

Answer 23

• ureterovesicle valves
• peristalsis
• mucous layer
• normal microbiota
• pH
• complete voidance of bladder

Question 24

UTI can spread to kidneys and cause _____

Answer 24

pyelonephritis

Question 25

causes of retrograde flow of urine from bladder to kidneys

Answer 25

- neurological disorders causing poor emptying of the bladder - hormones during pregnancy cause dilation and decreased peristalsis of the ureters - incomplete closing of ureterovesical valves in children

Question 26

causes of pyelonephritis

Answer 26

- retrograde flow of urine from bladder to kidney - urethral catheters - urinary tract stones

Question 27

some bacteria like ____ species can neutralize urine and cause formation of _____ or insolube precipitate that can damage vesicles

Answer 27

Proteus; "struvite" calculi

Question 28

UPEC can adhere to uroepithelial cells through ____

Answer 28

fimbriae

Question 29

uncomplicated UTI assoc with fimbrial antigen FimH

Answer 29

acute cystitis

Question 30

pyelonephritis is assoc with expression of ____

Answer 30

P fimbriae

Question 31

UPEC assoc with production of ____ and ____ associated with pyelonephritis and has a genetic link to ____

Answer 31

aerobactin; hemolysin; recurrent disease

Question 32

in addition to ____, ____ is another cause of uncomplicated UTI

Answer 32

UPEC; proteus mirabilis

Question 33

proteus mirabilis virulence factors

Answer 33

- flagella - an adhesion on the fimbrae is specific for urinary epithelium - hemolysins - IgA protease - Urease- enzyme that raises pH of urine

Question 34

effects of urease

Answer 34

- bacteria grow better in less acidic environment - toxic to renal cells - enhances formation of struvite (urinary stones) that can lead to a chronic infection

Question 35

proteus can be identified by:

Answer 35

- consistently alkaline urine | - production of urease

Question 36

treatment for UTI

Answer 36

- variety of antimicrobials | - trimethoprim-sulfamethoxazole (TMP/SMX) first choice

Question 37

large, mucoid colonies due to large capsule

Answer 37

Klebsiella

Question 38

____ important for adherence to urinary tract epithelium

Answer 38

type 1 pili

Question 39

____ important for adherence to respiratory tract epithelium

Answer 39

type 3 pili

Question 40

klebsiella enterotoxin similar to ____ so they can induce _____

Answer 40

ST and LT; secretory diarrhea

Question 41

klebsiella virulence factors

Answer 41

- pili (type 3) - enterotoxin - aerobactin- Fe sequestering - antiphagocytic capsule

Question 42

among the most prevalent gram negative GI bugs; "slow" bacterium

Answer 42

Helicobacter pylori

Question 43

H. pylori though to be transmitted through _____

Answer 43

oral to oral contact (as well as fecal to oral)

Question 44

in the GI tract, H. pylori only found in ____ overlying the _____ of the stomach

Answer 44

mucous; mucous-secreting cells

Question 45

H. pylori readily killed by ____; efficient producer of ____

Answer 45

gastric acid; urease

Question 46

h. pylori has _____ molecules- cause epithelial cells to produce ____

Answer 46

inflammatory effector; IL-8

Question 47

h. pylori cytotoxin is assoc with ____ (induces vacuolation and apoptosis of epithelial cells)

Answer 47

peptic ulcer disease

Question 48

h. pylori causes downregulation of _____

Answer 48

somatostatin-producing D-cells

Question 49

treatment for H. pylori includes use of a ____ and ____

Answer 49

proton pump inhibitor; antibiotic cocktail