L18, 19 : Gram Negative bacteria I

Question 1

lactose fermenting enterobacteria:
late lactose fermenting enterobaceteria:
non-lactose fermenting enterobacteria:

Answer 1

escherichia , klebshella

shigella sonnei

shigella , salmonella

Question 2

what type of enterobacteria are part of the normal flora in GIT ?

Answer 2

lactose fermenting ones

Question 3

what types of enterobacteria are intestinal pathogens ?

Answer 3

non-lactose fermenting ones

Question 4

E.coli properties ? :
gram test :
indole test :
lactose fermenting ?:

Answer 4

gram negative
indole test positive
lactose fermenting yes .

Question 5

what is the virulent function of LPS surface O Ag on E.coli bacteria ?

Answer 5

endotoxic activity , protects from phagocytosis

Question 6

which antigen is the flagellar antigen on E.coil?

Answer 6

H- antigen

Question 7

which surface antigen is the colonization factor?

Answer 7

Fimbriae

Question 8

describe the action of heat liable toxin of E.coli .

Answer 8

activates adenyl cyclase , which increases Cyclic AMP , which increases secretions of Na , Cl and water from cell

Question 9

describe the action of heat stable toxin of E.coli .

Answer 9

activates guanyl cyclase , which increases Cyclic GMP , which inhibits ionic uptake in intestinal cells –>osmotic water loss from cells

Question 10

which toxin of E.coli is ‘shigella-like’, and in what way ?

Answer 10

Verocytotoxin , which inhibits protein synthesis just like shigella toxins , leading to cell death

Question 11

which type of E.coli induces diarrhea that mostly affects infants , is non-toxigenic and non invasive ?

Answer 11

Enteropathogenic E.coli

Question 12

E.coli inducing travelers diarrhea that is non invasive but toxigenic :

Answer 12

enterotoxigenic E.coli ( resembles cholera )

Question 13

E.coli inducing bloody diarrhea (dysentery) that is similar to that of shigella :

Answer 13

enteroinvasive E.coli

Question 14

enterohemorrhagic E.coli produces which toxin ? and what are its effects on the body ?

Answer 14

verocytotoxin (shigella like toxin )

-Hemorrhagic colitis

-hemolytic uremic syndrome (renal failure , hemolytic anemia , thrombocytopenia )

Question 15

hemolytic uremic syndrome is a complication of which bacterial infection ? and what does it entail ?

Answer 15

enterhemorrhagic E.coli

renal failure , thrombocytopenia , hemolytic anemia

Question 16

what is a source of enterohemorrhagic E.coli?

Answer 16

improperly processed beef

Question 17

which type of E.coli infection has a stacked brink appearance and causes persistent diarrhea in infants in developing countries ?

Answer 17

enteroaggregative E.coli

Question 18

Klebsiella pnumoniae :
gram test ?
indole test ?
lactose fermenting ?

Answer 18

gram negative coccobacilli

indole negative

mucoid lactase fermenting

capsulated

Question 19

which bacterial infection produces currant jelly like sputum ?

Answer 19

Klebsiella pnumoniae

Question 20

what bacterial infections are most related to hospitalization ?

Answer 20

enterobacilli and serratia

Question 21

serratia :
gram test:
lactose fermenting :
pigment description :

Answer 21

gram negative
lactose fermenting
non-diffusible red pigment

Question 22

in what aerobic conditions do salmonella and shigella spp. grow ?

Answer 22

facultatively anaerobic (they posses fimbriae(colonizing factor))

Question 23

what clinical infections can salmonella spp. cause ?

Answer 23

-enteric fever / typhoid : S.typhi / S. paratyphi A,B ,C

-Food poisoning / acute gastroenteritis : serotypes of S.enterica

-septicemia : S. enterica serotype choleraesuis ( also involved in metastatic infections such as osteomylitis )

Question 24

where is salmonella commonly persistent in the body ?

Answer 24

gall bladder

Question 25

where do typhoid and other enteric fever begin?

Answer 25

they begin in the small intestine

Question 26

chronic carrier state :

Answer 26

persistence of salmonella in stool ( gall bladder ) or urine ( kidney ) for more than one year

Question 27

what does shigella cause ?

Answer 27

bacillary dysentery

Question 28

Shigella dysenteriae is an example of :

Answer 28

Group A shigella spp.

Question 29

how is shigella transmitted?

Answer 29

through feco-oral route

Question 30

how does shigella toxin function?

Answer 30

by inhibiting protein synthesis

Question 31

what does shigella toxin cause >?

Answer 31

dysentery and hemolytic uremic syndrome it also acts as a neurotoxin

Question 32

Which bacteria shows red colonies with black centers and no H2S ?

Answer 32

shigella

Question 33

what diseases does proteus infection cause ?

Answer 33

UTI pneumonia wound infections septicemia

Question 34

what property does proteus have that makes it easier for the bacteria to invade the urinary tract ?

Answer 34

vigorous motility

Question 35

what enzyme does proteus produce and what is that enzymes action?

Answer 35

urease , which breaks down urea in urine to form ammonia --> rasies pH of urine --> formation of stones ( calculi) called struvite stones which manifests as staghorn calculi in renal pelvis alkaline urine also favors growth of bacteria

Question 36

describe the growth of proteus on blood agar;

Answer 36

swarming growth

Question 37

what colonies does proteus form on MacConkey's agar ?

Answer 37

non-lactose fermenting

Question 38

what conditions do campylobacter jejuni bacteria grow best under ?

Answer 38

micro-aerophillic and 42 degrees

Question 39

what does campylobacter jejuni cause?

Answer 39

enterocolitis

Question 40

what bacterial infection is associated with guillain-barre syndrome , reactive arthritis , and reiters syndrome ?

Answer 40

campylobacter jejuni

Question 41

what are the sources of campylobacter jejuni?

Answer 41

raw/ undercooked meat unpasturized dairy products contaminated water contact with cat or dog feces

Question 42

H. pylori : gram test : urease test :

Answer 42

gram negative curved or spiral rods that are motile and strongly urease positive

Question 43

what diseases does H.pylori cause ?

Answer 43

gastritis and peptic ulcer gastric carcinoma MALT lymphoma

Question 44

which organism has darting motility

Answer 44

vibro cholerae

Question 45

what aerobic conditions are needed for vibrio cholerae to grow ?

Answer 45

strongly aerobic

Question 46

how is vibrio cholerae transmitted?

Answer 46

through food and water contaminated by feces of carrier

Question 47

what enrichment media does vibro cholera grow in ?

Answer 47

alkaline peptone water

Question 48

what selective media does vibriocholera grow in ?

Answer 48

TCBS