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Microbiology > Enteric Bacteria > Flashcards

Enteric Bacteria Flashcards

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Biology 101 flashcards
1
Q

What are enteric bacteria?

A

bacteria that cause gut infections

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2
Q

What are some ENTERIC bacteria? (11)

A 
Shigella
E. coli
Salmonella
Y. en-te-ro-co-li-ti-ca
Y. pseudotuberculosis
Vibrio
Campylobacter
Helicobacter
Bacteroides/Preveotella
Clostridium
Listeria
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3
Q

What are the three main groups the enterobacteriaceae are classified into?

A

Major Foodborne
Minor Foodborne
ICU Bugs

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4
Q

What are the major foodborne enterobacteriaceae? (3)

A

Shigella
E. coli
Salmonella

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5
Q

What are the minor food borne enterobacteriaceae? (2)

A

Y. enterocolitica

Y. pseudotuberculosis

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6
Q

What are the ICU bugs? (2x3)

A
  • Kleb-siella/Enterobacter/Serra-tia

- Proteus/Providencia/Mor-ganella

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7
Q

What are the DEFINING characteristics of enterobacteriaceae? (7)

A 
Gram (-)
Non-sporulating
Straight Rods
Facultative Aerobes
Catalase +
Oxidase -
Glucose Fermenters
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8
Q

COMMON characteristics of enterobacteriaceae?

A

Promiscuous to new DNA

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9
Q

How does promiscuous to new DNA play a role?

A

Acquired Gut Virulence Factors

Ab resistance

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10
Q

What are two types of acquired virulence factors?

A
  • -pili for adhesion

- -T3SS for adhesion and subverting Macrophages

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11
Q

What is the difference between commensalism E.coli and uropathogenic E.coli?

A

The acquisition of “P” Fimbriae (do to DNA uptake) –> adheres to bacteria inside urinary track –> UTI’s and kidney failure if not treated

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12
Q

Who are more susceptible to UTI’s?

A

Women of child bearing years

Individuals with diabetes

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13
Q

What are the addition of T3SS as virulence factors helpful for in Enterobacteriaceae?

A

Subverting Macrophages

They can directly pass materials from inside the bacteria (such as exotoxins) directly into the inside of the host cell

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14
Q

How do enterobacteriaceae get into the host cell? (2)

A

They either force the cell to form an actin bundle, which the bacteria can easily adhere to
Or they can subvert the endocytosis process and either
-use the endosome as a growth compartment
-escape the endosome and travel around cytosol freely

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15
Q

What is the typical infection of major food borne enterobacteriaceae?

A

Generally these bacteria can not penetrate the exterior part of the lumen. But they use M-cells to get into the lumen. They subvert the M-cells normal process of sampling, forcing the M-cells to refrain from killing them. Allowing the bacteria to pass through and reach the Macrophage. The MO then undergoes apoptosis–>releasing the bacteria into the sterile side. From here they attack the inside of the lumen and do a backward infection (intracellular infection)

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16
Q

What are M cells?

A

They are in charge of immunosurveillance of the lumen. The purposely pick up particle and microorganisms, sampling them and raising an immune response if necessary

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17
Q

What VF do these enterobacteriaceae need?

A

Ones to subvert endocytosis

Ones to induce apoptosis

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18
Q

What is an antimicrobial sensitivity assay?

A

It is to test for resistance of Antibiotics in certain bacteria

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19
Q

How do you perform it?

A

Spread an even layer of bacteria on plate
Place disk (previously soaked in diff antibiotics) on plate
Incubate
Check for clearance
Refer to the table to see if clearance is significant

20
Q

Salmonella

A

Gram (-)
Motile - flagella
> 2500 serovars exist
Usually aquired from contaminated food

21
Q

Why would it be difficult to make a vaccine against Salmonella?

A

There are far too many serovars (types)

22
Q

What is the pathogenesis of Salmonella?

A

Enterocolitis
Enteric Fever
–more server –> typhoid fever

23
Q

Enterocolitis causes?

A

Inflammation, diarrhea, nausea, vomiting

24
Q

About Enterocolitis

A
  • Immune response restricts it to the gut, spreading to the blood stream is rare
  • Need a high infectious dose
  • Gastric acid kills most (ppl on anti-acids are more susceptible)
  • Bacteria attach by fimbriae to cells lining the intestinal lumen
  • ->specifically M-cells of the Peyer’s patch
25
Q

What are the strains of Salmonella that cause enteric fever and typhoid fever

A

S. typhi

S. prathyphi

26
Q

About Enteric/Typhoid Fever PW

A

Human restricted (fecal-oral)
HIGH infectious dose
Invades Peyer patches of distal ilieum, and enters MO
Rides in MO through lymphatics–>invading major organs
Once critical density is reached–>MO apoptosis–>escape into bloodstream

27
Q

Enteric/Typhoid Fever Pathogenesis

A

Fever, malaise, abdominal pain, constipation
3-4 wk progression-dry cough, stupor, delerium,intestinal hemorrhage,bowel perforation,myocarditis, death
Necrosis of infected Peyer’s patches
–>hemorrhage/perforation
Other symptoms from toxemia
–>both endo and exotoxins

28
Q

What may survivors have?

A

long-term neurological sequale

CHRONIC carriage in gallbladder (reservoir)

29
Q

What are the two more severe outcome of enteric bacterial infections?

A

HUS - Hematolytic Uremic Syndrome

Reactive Arthritis

30
Q

How does HUS occur?

A

In rare instances bacteria (Shigella or a type of E.coli) escape the gut and enter the blood stream. There they release shiga toxins which can eventually lead to anemia and life threatening kidney failure

31
Q

How to test for HUS?

A

A blood smear is used

-will show normal RBC’s and schistocyte (sheared RBC’s)

32
Q

What is the treatment for HUS?

A

Antibiotics are controversial

They may actually make the disease worse

33
Q

What causes Reactive Arthritis?

A

It comes about when an individual carries HLA-B27. The exposure to certain gut bacterias or Chlamydia they brings about this autoimmune disease.
NOT life threathening

34
Q

How is Reactive Arthritis treated?

A

NSAID’s

35
Q

How is RA define?

A

Conjunctivitis, Urethritis, and Arthritis

36
Q

What are ICU bugs?

A

They are certain enterobacteriaceae that are not food borne (do not infect GI tract).
Have defining characteristics of enterobacteriaceae

37
Q

Where do these bugs come from?

A

Normal flora gone bad - opportunistic infection
Nosocomial infection - hospital aquired
Some are community-aquired diseases

38
Q

About Klebsiella pneumoniae (K.pneumonia)

A

Usually a pathogen that occurs due to a predesposing condition (advanced age, chronic resp disease, diabetes, alcoholism)

39
Q

What VF do K.pneumonia posses?

A

Large polysaccharide capsule-prevents phagocytosis by complement
Adhesins - adhere to gut cells
Siderophores - pick up iron and allow quicker reproduction

40
Q

K. pneumonia pathogenesis

A

Usually occurs in men w/ predisposing conditions–>causes lobar pheumonia w/ necrosis, inflammation, and hemorrhage, currant jelly sputum
50% lethal in alcoholics
100% lethal in alcoholics with bacteremia
Less lethal –> bronchitis, UTI, wound infection, catheter infection

41
Q

Diagnosis of ICU bug group?

A

Begin with culture
Gram stain - gram (-) rods
Antibiotic resistance testing

42
Q

Treatment of ICU bug group?

A

Begin with aminoglycoside and cephalosporin, and at same time run cultures and antibiotic sensitivity testing–to see which Ab’s the strain is resistant to

43
Q

Prevention of ICU bug group?

A

Prompt removal/relocation of catheters
Maintenance of resp therapy devices
Minimize hosp stays
Scrubdown of ICS and patients

44
Q

About Klebsiella

A

causes nosocomial outbreaks–among top 8 acquired infections

45
Q

K. oxytoca

A

Amoung top 4 pathogens in NICU’s

46
Q

Carbapenem-resistant K.pneumonia

A

Spreading around hospitals worldwide

Microbiology (10 decks)

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