Gram Negative Bacteria

Question 1

Name 3 genera of enterobacteriaceae

Answer 1

ESCHERICHIA, SALMONELLA, klebsiella, proteus, citrobacter, edwardsiella, yersinia, shigells (man and primates)

Question 2

Enterobacteria characteristics

Answer 2

gram negative rods or coccobacilli, motile and flagellated, facultative anaerobes, biochemically active (produce acid in gas/fermentation), oxidase negative, grow well on macconkey agar (resist bile salts, lactose fermenters)

Question 3

Which enterobacteria are lactose fermenters?

Answer 3

E. coli, Klebsiella spp.

Question 4

Scheme of serotyping to determine subdivision of enterobacteria?

Answer 4

based on O (somatic) and H (flagellar) antigens

Question 5

Ways to differentiate the subdivisions of enterobacteria

Answer 5

Serotyping, pathotypes, biotypes, phage typing, pulsed field gel electrophoresis (PFGE)

Question 6

Enterbacterial surface antigens

Answer 6

H (flagellar), O (LPS antigen), F(K) (fimbrae/pili), K (capsule) antigen

Question 7

No agglutination on slide indicates what?

Answer 7

The sample antigen was not reconized by the antibody

Question 8

Which enterobacteria are non lactose fermenters?

Answer 8

Salmonella sp, Proteus sp, Yersinia sp.

Question 9

Salmonella general route of infection

Answer 9

fecal -> oral

Question 10

Are salmonella invasive?

Answer 10

yes

Question 11

Syndromes of salmonella

Answer 11

Enteritis, Septicemia, Chronic infection /carrier state, Zoonosis

Question 12

Describe enteritis of salmonella

Answer 12

results in acute diarrhea w/ inflammation of gut, organisms restricted to gut tissue, don’t invade beyond mesenteric lymph nodes

Question 13

Describe septicemia of salmonella

Answer 13

organisms spread throughout body (usually by macrophages), grow in different organs, may lead to abortion/joint infections/pneumonia. +/- diarrhea

Question 14

Salmonella: enteritis vs. systemic infections (host range serotypes and zoonosis?)

Answer 14

Enteritis: broad host range serotypes, often zoonotic

Systemic infections: specific host range serotypes, generally NOT zoonotic

Question 15

Salmonella problems w/ treatment

Answer 15

Abx resistance, need for better vaccines

Question 16

Salmonella isolation and ID

Answer 16

sample brought in -> put in broth/ plated on agar -> pure colony put in strip wells -> also sent off to lab

Question 17

Reference lab tests for salmonella

Answer 17

Phage typing, DNA typing

Question 18

Species of salmonella?

Answer 18

S. enterica (99%), S. bongori

Question 19

Most important species of salmonella for warm blood mammals?

Answer 19

S. enterica subspecies I

Question 20

subspecies for cold blooded animals?

Answer 20

S. enterica, s.s. II, IIIa, IIIb, IV, VI - and s. bongori

Question 21

Serotypes of salmonella enterica

Answer 21

O antigens using sera against LPS = 1,2,3
Similar O types are into serotypes = A, B, C, D, E, etc.

H flagella antigens = Phase 1 H: a, b, c, etc.
Phase 2 H: i, ii, iii, etc.

Question 22

How many Salmonella serovars have capsules?

Answer 22

2 - S. typhi and S. paratyphi (but only human types)

Question 23

Non-host specific serotypes, symptoms they cause

Answer 23

S. typhimurium, S. enteritidis

• usually cause enteritis, mainly young animals
• imp. cause of food coloring in humans

Question 24

Host-specific serotypes, symptoms they cause

Answer 24

S. gallinarum, S. abortusovis, S. typhi

-often cause systemic infections, young or adult animals

Question 25

Host-restricted serovars

Answer 25

Preferentially infect one host but can infect others, S. dublin - cattle S. choleraesuis - pigs (both can infect humans, rarely, but serious when they do)

Question 26

Which serotype infects most animals?

Answer 26

S. typhimurium | emphasizes broad host range

Question 27

Necrotic ear example in calf

Answer 27

S. dublin (chronic salmonellosis)

Question 28

Dark blue hue in pig, periphery became cyanotic

Answer 28

S. choleraesuis (Septicemic salmonellosis)

Question 29

Pig w/ megacolon from rectal stricture

Answer 29

S. typhimurium

Question 30

Pathogenesis of host-adapted serotypes

Answer 30

Attracts macrophages to mediastinal lymph node, where they grow and replicate in macrophages and go through blood stream - to liver/spleen/bone marrow (growing the whole time) -> septicemic infection

Question 31

Pathogenesis of non-host adapted serotypes

Answer 31

Invasion through enterocytes or M cells (peyers patches) massive acute inflammatory repsonse, attracting neutrophils to the site and starts host response (and that is where the process stops) -> causing diarrhea and inflammation of the gut

Question 32

Salmonella attachment

Answer 32

Fimbrae: | each serotype can produce many different types of fimbrae/pili

Question 33

Salmonella engulfment by cell

Answer 33

Salmonella finds cell and mediates a molecular syringe to have the host cell engulf the bacteria

Question 34

Membrane ruffling

Answer 34

this occurs when the host cell engulfs the salmonella | Bacteria inducing its own uptake into the cell

Question 35

Type 3 secretion systems - explain molecular syringe

Answer 35

molecular syringes goes from cytoplasm of bacteria through outer membrane and into host cell membrane and cytoplasm - then injects effector proteins

Question 36

Pathogenicity Islands- salmonella

Answer 36

pathogenicity islands encode virulence genes SPI 1 = Type III secretion system, invasion of epithelial cells, enteritis (genes for membrane ruffling/diarrhea) SPI 2 = Type III secretion system, survival in macrophages (for systemic infections)

Question 37

Which pathogenicity islands do each salmonella have?

Answer 37

All salmonella have both pathogenicity islands, which one is expressed depends on where the organism finds itself in the body. (systemic or in gut)

Question 38

function of SPI 1 (sequence of events after activation)

Answer 38

secretes molecular syringe -> membrane ruffling -> salmonella internalized -> go into phagosome -> phagosome can go through to other side of cell -> to lamina propria, and then infection can begin

Question 39

Destruction of epithelium in enteritis

Answer 39

mainly due to inflammatory response by marked neutrophil influx elicited by salmonella (trying to kill salmonella but getting normal cells) -> this leads to diarrhea -> salmonella transmitted to others

Question 40

What is the electron acceptor which allows salmonella to grow, but not normal flora?

Answer 40

Tetrationate

Question 41

Survival strategies of Salmonella in macrophages

Answer 41

the Salmonella creates acidification by proton pump into phagosome, and prevents fusion of a lysosome to the phagosome. This means that the Salmonella survives in the phagosome SCV = salmonella containing vacuole mediated by SPI2!!

Question 42

Salmonella zoonosis

Answer 42

contracted from reptiles, meat, some veggies (if manured w/ animal feces)

Question 43

S. enteritidis PT4

Answer 43

poultry, eggs responsible for pandemic of salmonella food poisoning can invade oviduct, interior of eggs contaminated