Enterobacteriaceae Flashcards
(85 cards)
1
Q
Enterobacteria general characteristics (3)
A
- Facultative anaerobes
- Motile by peritrichous flagella (or nonmotile)
- Type 3 secretion system
2
Q
Enterobacteriaceae are typed by…
A
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
Q
What is IMViC?
A
- Indole - tryptophanase
- Methyl red - acid fermentation
- Voges-Proskauer - neutral fermentation
- Citrate - growth
4
Q
Gut bacteria can respond to…
A
neuroendocrone hormone levels
(e.g. E. coli and norepinephrine)
5
Q
Enterobacteria can inhibit the _______ in order to avoid immune detection
A
inflammasome
(Including NEMO,NFkB, IkBa, and MAPK)
6
Q
In many cell types, bacterial manipulation of vesicular trafficking promotes bacterial survival. This occurs largely by the manipulation of…
A
GTPase signaling
7
Q
E. coli metabolism and detection on growth medium
A
- Lac +
- Copius acid production
- Detected by green metallic sheen on EMB agar
8
Q
6 pathotypes of E. coli
A
- EPEC
- EHEC
- ETEC
- EAEC
- EIEC
- DAEC
9
Q
___ are the most common extra-intestinal E. coli infection
They are primarily caused by _____
A
UTI’s
UPEC (uropathogenic E.coli)
10
Q
___ is becoming an increasingly common pathotype for meningitis and sepsis
A
MNEC
(meningitis-associated E. coli)
11
Q
Three main presentations of E. coli infections
A
- Enteric (diarrheal)
- UTI
- Sepsis/meningitis
12
Q
E. coli causes ___% of UTI’s
These can spread to what organ?
This is associated with ____ (blood cell binding)
A
90% of UTI’s
spread to kidneys (vesicoureteral reflux) to cause pyelonephritis
Associated with P pilus
13
Q
5 E. coli pathotypes that cause diarrhea
A
P, T, H, I, A
14
Q
EPEC diarrhea
A
(attachment protein, bundle forming pili)
efface small intestine microvilli –> inhibit water uptake
- Watery, self limiting diarrhea
- common in young children
15
Q
ETEC, a.k.a…
A
Traveler’s diarrhea
Watery, increased motility & cramping
16
Q
Pathotype of E. coli that is associated with CFA adhesion protein for brush border membrane
A
ETEC
17
Q
ETEC toxins
A
-
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
Q
EHEC causes ____ diarrhea, without…
A
Bloody diarrhea without fever
19
Q
EHEC toxin name and 3 characteristics
A
verotoxin (Shiga-like toxin)
- AB toxin
- Protein synthesis inhibitor
- acquired by phage conversion
20
Q
EHEC has a tropism for what tissue?
A
Kidney
21
Q
E. coli strain (EHEC) responsible for community epidemics from contaminated meat, water, or vegetable produce?
A
0157:H7
22
Q
Disease caused by EHEC
What is its pathology? How is this handled?
A
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
Q
EIEC diarrhea
A
“Invades” the colon, causing bloody diarrhea
24
Q
EIEC is indistinguishable from…
A
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, E**_A_**EC)
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
