Vibrios

Question 1

Gram negative or positive

Answer 1

Gram negative

Question 2

Physical shape of bacteria

Answer 2

Comma shaped rod

Question 3

Flagellum and nucleic acid

Answer 3

• polar flagellum

- 2 circular chromosomes

Question 4

pH sensitivity of vibrio

Answer 4

• highly alkali tolerant(pH 9)

- acid sensitive(pH<6)

Question 5

Relationship between vibrios and copepods

Answer 5

• halotolerant and some halophilic(saline environments)

- resident on copepods

Question 6

Major type of V. cholerae

Answer 6

O1 strain with no capsule

Question 7

2 types of biotypes of O1 strain

Answer 7

Classical and El Tor

Question 8

2 serotypes of each biotype

Answer 8

Ogawa and Inaba

Question 9

Mutation type of El Tor

Answer 9

Mutation into O139

Question 10

Description of O139

Answer 10

• polysaccharide capsule

- local epidemic in Calcutta

Question 11

Difference between El Tor and Classical

Answer 11

• polymyxin resistant
• produces hemolysin
• less toxic produced, but colonized better
• outgrows classical biotype in mixed culture

Question 12

Pandemics due to Classical and El Tor

Answer 12

• Classical biotype for 6 pandemics

- El Tor biotype for 1961-2001 pandemics

Question 13

Colony numbers required for bacteria

Answer 13

• large numbers of bacteria to colonize(10^6)

- with antacid, 10^3 and El Tor advantage

Question 14

Location where disease presents

Answer 14

Mainly small intestines

Question 15

Incubation period and initial presentation

Answer 15

• 1 to 4 days

- Nausea, vomiting, 1-2 loose stools

Question 16

Acute onset of clinical presentation

Answer 16

• watery diarrhea(>20L per day), like rice water stool
• contains mucus, lots of vibrio, no blood
• no fever or pain

Question 17

Risk of watery diarrhea due to V. Cholerae

Answer 17

-dehydration and electrolytes loss causes circulatory collapse and death

Question 18

Epidemiological of V. Cholerae

Answer 18

• worldwide distribution in water

- filtration of copepods, and sari cloth

Question 19

Natural host of V. Cholerae

Answer 19

-humans

Question 20

Spread of V. Cholerae

Answer 20

-ingested in fecally contaminated water or food

Question 21

Onset of V. Cholerae

Answer 21

• usually a few days
• may carry bacteria for 3-4wks
• rare long term carriers

Question 22

Pathogenesis of V. Cholerae

Answer 22

-fimbriae bind to gut epithelium

Question 23

Toxin of V. Cholerae

Answer 23

• toxin and pilus genes regulated by ToxT

- ToxT mRNA is regulated by temperature-sensitive riboswitch

Question 24

Toxin description

Answer 24

• AB5 toxin, A is in 2 subunits linked by S-S
• B binds as pentamer to receptor ganglioside Gm1(epithelial)
• A1/A2 S-S bond is reduced and A1 uses NAD to ADP ribosylate a Gs protein

Question 25

Consequence of S-S bond being reduced

Answer 25

- activates adenyl cyclase - increase cAMP causes ion secretion into gut lumen - water follows to balance osmolarity

Question 26

Control of V. Cholerae

Answer 26

- rehydration and electrolyte replacement - Oral Rehydration salts - doycycline can limit vibrios shedding(only >10%) - vaccines not very effective

Question 27

Clinical of V. Parahemolyticus

Answer 27

- halophilic - 12 to 24hrs incubation, nausea, vomiting, watery to bloody diarrhea, possibility gastroenteritis - self limiting, resolves 1-4 days

Question 28

Epidemiological of V. Parahemolyticus

Answer 28

- worldwide distribution in ocean waters - consumed in contaminated(raw or undercooked seafood) - Japan and Atlantic coast

Question 29

Pathogenesis of V. Parahemolyticus

Answer 29

-biofilms, T3SS, T6SS, hemolytic/cytotoxic enterotoxin

Question 30

Control of V. Parahemolyticus

Answer 30

- rehydration and electrolyte replacement | - doxycycline if necessary

Question 31

Clinical of V. Vulnificus

Answer 31

- infected wounds from handling contaminated seafood - bacteremia from eating raw oysters - very rapid cellulitis and necrosis - eventual liver damage(alcoholic predisposition)

Question 32

Epidemiology of V. Vulnificus

Answer 32

- always associated with contaminated seawater or seafood | - endemic in TX, AL, LA

Question 33

Pathogenesis of V. Vulnificus

Answer 33

- antiphagocytic capsule contributes to virulence | - necrotizing cytotoxin

Question 34

Control of V. Vulnificus

Answer 34

- doxycycline right away - Cipro. if pregnant - takes 18hrs to get a positive culture; too late