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Flashcards in Enterobacteriaceae Deck (85):
1

Enterobacteria general characteristics (3)

  1. Facultative anaerobes
  2. Motile by peritrichous flagella (or nonmotile)
  3. Type 3 secretion system

 

2

Enterobacteriaceae are typed by...

Antigens: O, H, K/Vi

  • all have capsules but large only in Klebsiella

Biochemical tests

  • IMViC
  • CHO fermentation: especialy lactose (MacConkey's Agar)
    • Lac+ are coliforms

3

What is IMViC?

 

  • Indole - tryptophanase
  • Methyl red - acid fermentation
  • Voges-Proskauer - neutral fermentation
  • Citrate - growth

4

Gut bacteria can respond to...

 

neuroendocrone hormone levels

(e.g. E. coli and norepinephrine)

5

Enterobacteria can inhibit the _______ in order to avoid immune detection

inflammasome

 

(Including NEMO,NFkB, IkBa, and MAPK)

6

In many cell types, bacterial manipulation of vesicular trafficking promotes bacterial survival. This occurs largely by the manipulation of...

GTPase signaling

7

E. coli metabolism and detection on growth medium

  • Lac +
  • Copius acid production
  • Detected by green metallic sheen on EMB agar

8

6 pathotypes of E. coli

  1. EPEC
  2. EHEC
  3. ETEC
  4. EAEC
  5. EIEC
  6. DAEC

9

___ are the most common extra-intestinal E. coli infection

They are primarily caused by _____

UTI's

UPEC (uropathogenic E.coli)

10

___ is becoming an increasingly common pathotype for meningitis and sepsis

MNEC

(meningitis-associated E. coli)

11

Three main presentations of E. coli infections

  1. Enteric (diarrheal)
  2. UTI
  3. Sepsis/meningitis

12

E. coli causes ___% of UTI's

These can spread to what organ?

This is associated with ____ (blood cell binding)

 

90% of UTI's

spread to kidneys (vesicoureteral reflux) to cause pyelonephritis

Associated with P pilus

13

5 E. coli pathotypes that cause diarrhea

P, T, H, I, A

14

EPEC diarrhea

(attachment protein, bundle forming pili)

efface small intestine microvilli --> inhibit water uptake

  • Watery, self limiting diarrhea
  • common in young children

15

ETEC, a.k.a...

Traveler's diarrhea

Watery, increased motility & cramping

16

Pathotype of E. coli that is associated with CFA adhesion protein for brush border membrane

ETEC

17

ETEC toxins

 

  • 2 LT toxins
    • LT1 is an AB toxin (like Cholera...increases camp to cause secretory diarrhea)
  • 2 ST toxins
    • activate cGMP production (water secretion)

18

EHEC causes ____ diarrhea, without...

Bloody diarrhea without fever

19

EHEC toxin name and 3 characteristics

verotoxin (Shiga-like toxin)

  • AB toxin
  • Protein synthesis inhibitor
  • acquired by phage conversion

20

EHEC has a tropism for what tissue?

Kidney

21

E. coli strain (EHEC) responsible for community epidemics from contaminated meat, water, or vegetable produce?

0157:H7

22

Disease caused by EHEC

What is its pathology? How is this handled?

Hemolytic Uremic Syndrome

  • Damage to glomerular enothelium (by systemic toxin) causes uremia and organ failure
  • You DO NOT GIVE ANTIBIOTICS for this disease -- they upregulate the Stx gene (toxin)

23

EIEC diarrhea

"Invades" the colon, causing bloody diarrhea

 

24

EIEC is indistinguishable from...

Shigella dysenteriae (type 1)

25

EIEC colonization factor

Ipas

Produced from Shigella plasmid

26

This E. coli pathotype is known to form a biofilm on the intestine

 

EAEC

--causes malapsorptive-type diarrhea

27

When I say "noninflammatory pediatric diarrhea in developing countries, that is also the #2 cause of travelers' diarrhea in most countries" you tell me that this is...

EAEC

28

EAEC form ______ via ______ in intestine

infective foci via "aggregative pili"

(hence, EAEC)

29

___, ___, and __ hit the small intestine

___ and ___ hit the large intestine

Small = EPEC, ETEC, EAEC

Large = EHEC, EIEC

30

The E. coli pathotypes that cause bloody diarrhea tend to hit where?

Large intestine

31

Major E. coli cause of neonatal meningitis?

 

What is it's major pathogenic characteristic?

E. coli K1

  • most meningitis strains have K1 capsule
  • It functions as a molecular mimic of host's NCAM receptors

32

E. coli K1 capsule is similar to...

N. meningitidis B capsular antigen

 

33

Salmonella metabolism and growth characteristics

  • Lac (-)
  • H2S (+) - S-S agar
  • Grows in selective media with Bile salts (deoxycholate)

 

34

All Salmonella belong to _____ species, with how many subspecies?

 

  • S. enterica
  • 6 subspecies (e.g. S. enterica ssp. arizonae)

35

It is only important (for us) to distinguish what two Salmonella subspecies?

Typhi + Paratyphi

36

Salmonella diseases (and subspecies that cause)

  1. Typhoid fever (S. typhi or S. paratyphi)
  2. Bacteremia/Septicemia (S. cholerasuis)
  3. Enterocolitis / GE (S. Enteriditis)

37

Typhoid fever is a ____ disease that disseminates via ______to liver, GB

Death is usually from _______

invasive disease, disseminates via macrophages

death from intestinal hemorrhage

38

Salmonella septicemia mainly hits whom?

immunocompromised patients

39

Salmonella enterocolitis/gastroenteritis clinical features (3)

  • nausea, profuse diarrhea, FEVER
  • self limiting within 2-5 days
  • may colonize GB and shed for weeks

 

40

Salmonella Enteriditis is especially transmitted via...

egg and poultry products

41

Two distinct features of Typhoid fever

  1. High sustained fever
  2. Roseate rash

42

Salmonella spread via

fecal-oral

from contaminated water, endemic sources in eggs and poultry, crops fertilized with human excreta, and pets

43

Salmonella pathogenic steps (4)

  1. Binds brush border
  2. invades gut epithelial cells
  3. invades deep tissues and bloodstream through the basal membrane
  4. produces cytotoxic enterotoxin

 

44

Typhoid toxin characteristics and function

A2B5 toxin

can grow in bile using efflux pumps and DNA repair to survive

Uses phospholipids as a carbon source

 

  1. A1 = ADP ribosylates G protein
  2. A2 = Damages DNA and stops replication of cell

45

Salmonella cytotoxin may cause _____

bloody diarrhea

46

Salmonella survives within...

MQ's

47

Shigella metabolism and characteristics

Lac-,  H2S- (S-S Agar)

Looks like other enterobacteriaceae

48

Shigella types

dysenteriae

flexneri (3rd world)

boydii

sonnei (US)

49

Shigella does not result in

systemic infection / sepsis

 

(only a GI pathogen)

50

Shigella diarrhea timeline

 

  • acute onset watery diarrhea (WITH FEVER)
  • 2 days later the volume is less, but more mucus/blood in stool
  • Resolves in ~one week

51

Shigella transmits via

fecal oral

Spread via 4 F's!

  1. Food
  2. Fingers
  3. Feces
  4. Flies

Associated with crowded unsanitary conditions

52

Shigella pathogenic steps

  1. Phagocytosed and transmitted by M cells
  2. engulfed by MQ
  3. Lyse MQ phagolysosome and replicate in cytoplasm
  4. MQ undergoes apoptosis

53

How does shigella change the basal membrane/cell-cell interactions?

Releases IL-1 and other cytokines to permeabilize the cell junctions

Induces Basal membrane phagocytosis by lumenal cells

Can spread via actin tails

54

What are shigella IPAS?

Invasion factors

secreted by T3SS

55

How does shiga enterotoxin kill cells?

It disrupts protein synthesis

56

"Classic symptom" of shigella

fecal leukocytes

 

(gaps opened up in the basal membrane by shigella cause leakage of polymorpholeukocytes, which show up in stool sample)

57

Yersinia may or may not be...

GIT infection

58

Yersinia appearance

Looks like other enterobacteriaceae, but may be coccobacillus

59

Yersinia staining

Bipolar

(Wright-Giemsa stain, Wayson's)

60

Yersinia - three general pathogenic factors

  • YadA adhesin
  • YOP (T3SS encoded by plasmid)
  • V and W antigens (allow for intracellular growth)

61

Non-GI version of yersinia

Y. pestis

  • Zoonosis
  • Bubonic = most common form
  • painful buboes in groin or other lymph node

 

62

It is essential that yersinia buboes are differentiated from which other conditions/pathogens?

tularemia & pasteurella

63

Less common form of Yersinia pestis?

What are the characteristics?

Symptoms?

Septicemic

  • may be primary/secondary to bubonic
  • (if secondary, it develops within a few days of the appearance of buboe

Sx = purpura, DIC, necrosis

64

Third presentation of yersinia pestis?

What are the types/origin, symptoms?

What shows up on labs/imaging?

Pneumonic

  • Primary from inhalation, Secondary from DIC
  • X-rays show bilateral alveolar involvement

65

Y. pestis spread via ____

rat flea (xenopsylla cheopis)

 

  1. Bacteria toxin blocks fleas gut - clot forms
  2. When flea bites again, the clot is transferred into the animal host

66

Main reservoirs for Y. pestis in the US?

deer mice

ground squirrels (prairie dogs)

67

Yersinia pestis pathogenesis (in flea and mammal)

Flea:

  1. YMT phospholipase helps survival within flea (key to expanding host range)

Human:

  1. Capsular genes turned on at 37 degrees
  2. Yop T3SS injects toxins
  3. MAPK pathway is inhibited by Yop-J
  4. Phagocytosis is prevented by Yop-E
  5. Platelet aggregation is inhibited by Yop-M

68

Yersinia YopJ effects

Inhibits MAPK pathway

  • prevents cytokine production
  • prevents cell replication (apoptosis and necrosis)

69

Y. pestis control is based around

prevention: insecticide kills fleas before infection

70

Is there a Yersinia pestis vaccine?

Yes! Formalin-killed OR live attenuated

*must be boosted every year, so it's only for people who are repetedly exposed

71

Y. pestis post-exposure treatments

Oral tetracycline for those exposed but asymptomatic

streptomycin (i.m.) for symptomatic pts.

 

**pneumonic plague treatment is rarely successful (virtually 100% fatal within 24 hours)

72

GiT version of yersinia

Y. enterocolitica

Y. pseudotuberculosis

73

2 major Y. enterocolitica symptoms

 

  1. enterocolitis with intestinal abscesses (SEVERE bloody diarrhea)
  2. Mesenteric adenitis (mimics appendicitis)

 

74

GIT yersinia reservoirs and spread

Cattle/hog reservoir

Spread in feces or via contaminated drinking water/milk

75

Control for Yersinia enterocolitica/pseudotuberculosis

Ampicillin

*note: does NOT control y. pestis

Can also use Third Gen Ceph's or Bactrim

76

What are the "other" enterobacteriaceae?

  • Klebsiella pneumoniae
  • Klebsiella oxytoca
  • Klebsiella granulatomatis
  • Proteus mirabilis
  • Proteus vulgaris
  • Serratia marcascens

77

K. pneumoniae virulence, symptoms/prognosis

virulence = large capsule

hemorrhagic, necrotizing infection (currant jelly)

50-100% fatal

78

K granulomatis infection type

Possible presentation?

STD, not GIT

Donavonosis = "granuloma inguinale" = granulomatous infection that can mimic syphillis

79

K. granulomatis may mimic...

  1. syphillis (genital granulomas)
  2. genital cancers (because of progressive destruction of tissue)

80

What enterobacteriaceae exhibit "swarming motility" on agar?

 

What other pathogenic feature is present in this organism, and what happens as a result of it?

Proteus! (due to many flagella)

** this makes it ascent possible in the urinary tract -- Associated with UTI

 

Proteus also makes UREASE (similar to mycoplasma)

  • causes alkaline urine, precipitates formation of BLADDER STONES

81

Serratia marcescens:

  • Infection route?
  • What kinds of infections that tend to result?

  • Opportunistic nosocomial pathogen
  • PNA, bacteremia, endocarditis

 

** in immunocompromised patients

82

General control for "other enterobacteriaceae"

What antibiotics can we use (if any)?

 

General control: isolate source and decontaminate (esp. for fecal oral)

Antibiotics: Ampicillin, Third Gen Ceph's, Quinolones, Sulfas, Streptomycin

**Antibiotic resistance greatly influences ability to treat. (R plasmids are very common in enterobacteriaceae)

 

83

Antibiotic guidelines for uncomplicated UTI (enterbacteriaceae)

BACTRIM is 1st choice, followed by Fosfomycin

 

DON'T use fluoroquinolones (resistance)

84

Most common prophylactic for traveler's diarrhea

Rifamixin

85

What is MUC2? What are three things it does?

  • hyperglycosylated mucin
  • subdues inflammatory response from Dendritic cells
  • stimulates production of Treg cells (by DC signaling)
  • Normal flora use it as a carbon source --> non-inflammatory