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MSE-2019 Medical Microbiology > Lecture 3 Gram Negative > Flashcards

Lecture 3 Gram Negative Flashcards

(60 cards)

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1
Q

ToD: Gram negative bacteria make up the largest group of human bacterial pathogens

A

True

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2
Q

What do gram negative bacteria tend to look like?

A

Cocci, bacilli and coccobacilli

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3
Q

What is an important identifying factor for gram negative bacteria?

A

Lipid A

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4
Q

Where can Lipid A be found?

A

Cell wall

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5
Q

What symptoms can Lipid A cause?

A

Fever, vasodilation, inflammation, shock and DIC (disseminated intravascular coagulation which is the formation of blood clots within the blood vessels in the body)

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6
Q

Where can enterobacteriaceae be found?

A

The flora of the intestines in both humans and animals
Water
Soil
Decaying vegetation

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7
Q

ToD: Enterobacteriaceae are opportunistic

A

False. It’s a mix of pathogenic and opportunistic

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8
Q

What kind of infections are enterobacteriaceae mostly responsible for?

A

Nosocomial infections

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9
Q

What do enterobacteriaceae look like? (think shape & structures)

A

Coccobacilli
Bacilli
Some have flagella or are covered in them
Capsulated/Slime/Biofilm

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10
Q

ToD: Enterobacteriaceae are all oxidase negative

A

True

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11
Q

ToD: All enterobacteriaceae reduce nitrite to nitrate

A

False.
Nitrate -> Nitrite
Not the other way around

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12
Q

What kind of respiration does Enterobacteriaceae do?

A

Prefers aerobic but can able to ferment glucose anaerobic

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13
Q

What 3 major components are found in the cell wall of Gram-ve?

A

Strain-specific O-polysaccharide
Core Polysaccharide
Lipid A

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14
Q

What do flagellar proteins contain?

A

H antigens

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15
Q

What is found in the protein and polysaccharide capsular? (antigen)

A

K antigens

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16
Q

How are Gram-ve bacteria able to evade the immune system?

A

Can control the genetic expression of antigens (K or H antigens)

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17
Q

What are the 7 virulence factors for Gram-ve?

A

Lipid A
Capsules
Fimbriae
Exotoxins
Iron binding compounds
Haemolysins
Type III secretion system

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18
Q

What antigens can be used to identify E.coli?

A

O, H and K antigens

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19
Q

What is the term for the transfer of genetic material between unicellular or multicellular organisms?

A

Horizontal gene transfer or lateral gene transfer

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20
Q

What diseases can the virulent strains of E.coli produce?

A

UTIs
Neonatal meningitis
Gastroenteritis
Severe to fatal haemorrhagic colitis

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21
Q

What is the name of the toxin produced by enterohemorrhagic E.coli?

A

Shiga toxin or Vero toxin

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22
Q

What treatment and prevention methods are there for E.coli?

A

Good personal hygiene
Various antimicrobials
Don’t ingest infected substances

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23
Q

Why is bactericide not recommended for E.coli?

A

Lysing the cell can distribute more toxins into the blood as Lipid A is stored in the cell wall

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24
Q

Name the 3 pathogenic enterobacteriaceae

A

Salmonella, Shigella and Yesinia

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25
What do all 3 pathogenic enterobacteriaceae have in common?
All synthesise type III Has secretion systems
26
What are the characteristics of Salmonella?
Gram negative Facultatively anaerobic Most motile due to peritrichous flagella Pathogenic to both humans and animals
27
How is Salmonella distributed in the environment?
Intestinal tract of birds (magpie) /animals Sewage Fertilisers Slurry Animal feeds Human carriers
28
Name some foods that may contain salmonella
Meat Milk Fish Egg Confectioner Dried Yeast Frogs legs Marijuana Peanut butter
29
What are the symptoms that you might have salmonella?
Enteritis Diarrhoea Abdominal pain Mild fever Chills Nausea Vomiting
30
What two strains of Salmonella can cause enteric fevers?
S.typhi S. paratyphi
31
Where does salmonella like to reside in the body when its invaded?
Sticks to the epithelial lining of the ileum using their fimbriae, where they invade cells and multiply
32
What is produced by salmonella that endangers the body?
On the third day of Xmas... 3 enterotoxins, some cytotoxin and the Lipid A in the cell wall
33
What are some methods to prevent salmonella infection?
Basic food hygiene Control starts at the farm and continues through the chain until it reaches the consumer Don't be stupid Agriculture + Food sectors are held responsible
34
Where can you find S.typhi?
Contaminated food/water
35
How does S.typhi infect the body?
Bacteria pass through the intestinal wall to the bloodstream. WBCs phagocytose S.typhi however it's not killed, allowing it to travel across the body to prime locations such as the liver, spleen, bone marrow and gall bladder
36
What are the symptoms of S.typhi infection?
Fever Headache Malaise Muscle pain Loss of appetite All last about a week
37
Can you explain why S.typhi causes the symptoms seen in the infected? (Two points)
Bacteria is released from the gallbladder which reinfects the intestines = Gastroenteritis abdominal pain and recurring bacteremia Some bacteria can ulcerate and perforate intestinal wall causing peritonitis in the abdominal cavity
38
What are the characteristics of Shigella?
Gram negative Non-spore forming Rod-shaped bacteria Causes disease in primates but not other mammals
39
What disease does Shigella cause?
Shigellosis.
40
What symptoms does Shigella cause?
Dysentery
41
Why does dysentery occur during a Shigella infection?
The epithelial cells of the intestinal mucosa are destroyed in the cecum and rectum. Using the Type III secretion system, it invades the epithelial cells of the large intestine.
42
What three toxins are created by the various strains of Shigella?
Shiga toxin Verotoxin Enterotoxin
43
How does a Shigella infection usually occur?
Ingestion (fecal-oral contamination)
44
What does each Shigella genome include?
The virulence plasmid. This encodes the conserved primary virulence determinants
45
What disease does Shigella chromosomes have in common?
Shigella chromosomes share most of their genes with E.coli K12 strain MG1655
46
What is the treatment for someone that is infected by Shigella?
Replacing fluids/electrolytes Oral antibiotics (e.g Ciprofloxacina & Cephalosprins) to reduce the spread in close contacts
47
ToD: There is a vaccine against Shigella
False. The vaccine is still being developed. It's seen some success against S.flexneri
48
What are the 3 notable species of Yersina?
Y.enterocolitica Y.pseudotuberculosis Y.pestis
49
In Yersina how many virulence plasmids are there?
3
50
What do the virulence plasmids in Yersina encode for?
Adhesions and Type III systems
51
Who does Yersina like to infect?
Typically animals
52
What is the infection pathway of Y.enterocolitica and Y.pseudotuberculosis?
Contaminated food/water by animal faeces
53
What are the symptoms of Y.enterocolitica in children?
Fever Abdominal pain Diarrhea (often bloody)
54
What are the symptoms of Y.enterocolitica in older children and adults?
Right-sided abdominal pain Fever Inflammation of mesenteric lymph nodes Can be confused for appendicitis
55
What is Yersinia pestis also known as?
The Black Death
56
How was Yersinia pestis spread?
Rodent fleas
57
What can treat Yersina pestis?
Modern antibiotics
58
What are the symptoms of the bubonic plague?
Swollen lymph nodes Bacteremia which results in disseminated intravascular coagulation Subcutaneous haemorrhaging Tissue death
59
What are the symptoms of the Pneumonic plague?
Pulmonary distress within a day
60
How is the Pneumonic plague spread?
Spreads via person to person via aerosols and sputum

MSE-2019 Medical Microbiology (6 decks)

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