Salmonella and Shigella Flashcards Preview

Microbio 2 > Salmonella and Shigella > Flashcards

Flashcards in Salmonella and Shigella Deck (30):
1

what family is salmonella apart of?

enterobacteriaciae

2

what is the general morphology of salmonella?

gram - rods

3

where in the body does salmonella affect?

GI tract

4

what are the 3 distinguishable syndromes related to salmonella?

typhoid/enteric fever- S. typhi

septicemia- S. cholerasuis

acute gastroenteritis- S enteriditis or S typhimurium

5

S typhi

causes typhoid fever- common in developing world

6

S typhi incubation period

7-14 days

7

S typhi symptoms

episodic fever, bradycardia, rose spot, leukopenia, enlarged liver and spleen

intestinal hemorrhage or perforation during late stages

8

describe S Typhi lifecycle in the body

infects orally. resistant to acid killing. adhesins attach to intestinal epithelium.

eaten by macrophages. survives in lysosome. kills macrophage and spreads to blood, liver, spleen via lymph.

infection in blood causes fever and shock. can reinvade intestine from gall bladder

9

S typhi pathogenicity islands

SPI-1 - invasion; SPI-2- survival

SPI-1- type 3 secretion system- secretion where a protein moves across bacterial and host cell membranes in injecition needle. In Salmonella, delivers toxins that induce membrane ruffling via actin

10

virulence factors for S typhi

pathogenicity islands and Gram - LPS containing endotoxin

11

S typhi diagnosis

1st week- stool culture
2/3 week- blood cultures (symptomatic patients)
3+ week- blood and stool

12

s typhi treatment

fluoroquinolones or 3rd generation cephlosporins

chronic gall bladder infection treated with ampicillin/fluroquinolones or resection

13

what antigen exists only on S typhi

V1- polysaccharide capsule

14

S typhi vaccines

both against v1 Ag

Ty21a- oral, 4 doses, must be 6, booster needed every 5 years, need 1 week before exposure

ViCPS- injection, 1 dose, booster needed every 2 years, must be 2, need 2 weeks before exposure

15

S cholerasuis infection method

oral- from swine

infectious dose- 1000

16

S cholerasuis incubation period

6-72 hours

17

S cholerasuis signs/symptoms

high fever, bacteremia, gastroenteritis, microabcesses in any tissue

18

S enteriditis and S typhimurium infection routes

most common salmonella infections in US

EGGS, poultry, pork, dog food, fruits/veggies, pets, sandboxes

19

S enteriditis and S typhimurium symptoms

diarrhea, headache, chills, vomitting, fever

very rarely progresses to blood

20

S enteriditis and S typhimurium incubatoin and duration

8-48 hr incubation

1-4 day duration

21

S enteriditis and S typhimurium virulence factors

LPS release

T3SS

toxins that promote inflammation and secretion

22

diagnostic features of salmonella

isolation in feces

ferment glucose, oxidase negative, reduce nitrate

does not ferment lactose (MacConkey or EMB Agar)

motile

urease negative

indole negative

23

Shigella types

S dysenteriae- developing world

S flexneri- common in US and developing countries

S sonnei- most common in US

S boydii- common in india

24

shigella infection types

food, fingers, feces, flies

children under 10 more susceptible

25

shigella symptoms

fever (LPS), diarrhea (bloody/mucus), abdominal cramps

bacteremia rare

self limiting

hemolytic uremic syndrome associated w/ dysenteriae

26

shigella pathogenesis

low infectious dose- 100
acid tolerance
incubation 1-4 days

invades ileum and colon. phagocytozed but escapes via causing apoptosis

IL-1 and TNF from monocytic cells causes fever

diarrhea b/c poor fluid uptake, ulceration d/t shiga toxin (dysenteriae)

27

shiga toxin

exotoxin- A/B subunits

A- interferes w/ 60S ribosome subunit
B- intestinal adherence

28

shigella treatment

fluid replacement, antibiotics only in severe cases

29

diagnosis of shigella

cant from symptoms

isolation from feces- PMNs indicative of disease

no gas w/ glucose fermentation
no lactose fermentation
no H2S
non motile (no H antigen)
urease negative
indole negative

30

shigella vaccine

none