Gih Week 3: Viruses And Bacteria

Front 1

What are the characteristics of the Rotavirus genome?

Enveloped?

Back 1

Segmented ds RNA

Non-enveloped

Triple layered virus

Front 2

Which virus causes viral gastroenteritis?

Back 2

Rotavirus

Front 3

What is the most common cause of severe diarrhea among young children worldwide?

Back 3

Rotavirus

(children 6 months-- 3 years old)

*Major cause of diarrhea in those <2 yrs old
*Especially dangerous in malnourished children

Front 4

Which virus infects plants, fungi, and humans?

Back 4

Rotavirus

Front 5

What are the 3 layers of the Rotavirus?

Back 5

1. Virion (sugar/protein coating)
2. ISVP (Infectious subvirus particle)
3. Core

Front 6

Are Rotavirus infections seasonal or year-round in tropical countries?

What about in temperate climates?

Back 6

Tropical --> year round infections

Temperate --> winter epidemics

Front 7

Would you expect blood or fecal leukocytes to be present in the stools of an individual infected with Rotavirus?

Back 7

No

Front 8

Which virus typically affects young children, and results in watery stools and vomiting after a 1-2 day incubation period?

Back 8

Rotavirus

Front 9

What two Rotavirus surface proteins are targeted by neutralizing antibodies?

Back 9

VP4 and VP7

Front 10

Which type of antibody is thought to be responsible for protection against Rotavirus-- is it a mucous or systemic Ab?

Back 10

Mucous antibody
(directed against VP4 or VP7 surface antigens)

Front 11

Why was Rotashield withdrawn from market?

Which other two vaccines can be used instead?

Back 11

It triggered intussesception (telescoping of intestines) in a handful of children

1. Rotarix (crippled strain of live human rotavirus)
2. RotaTeq (5 different disabled rotaviruses, each a combo of strains from humans and cows)

Front 12

What are the characteristics of the Notavirus genome?

Is it enveloped?

Back 12

ssRNA
(+) sense

Non-eveloped

Front 13

Which group of viruses is the main cause of non-bacterial diarrhea in children >2 yrs old and adults?

Back 13

Noroviruses
(Norwalk and Norwalk-like)

*These are caliciviruses

Front 14

Which virus is the most common cause of epidemics of viral gastroenteritis in schools, camps, and cruise ships?

Back 14

Norovirus

Front 15

Which virus is the most common cause of outbreaks of gastroenteritis in industrialized areas?

Back 15

Norovirus

*Infection control measures are critical to limit outbreaks in hospitals-- patients must be isolated

Front 16

Why does Rotavirus result in large net volume of water secretion?

Back 16

The virus causes Cl- ion secretion which results in large net volume of water secretion to achieve osmotic balance

Front 17

Do antibodies to norovirus serve long term protection?

Back 17

No, so reinfection is possible.

(Antibodies to Rotavirus, however, CAN confer long-term immunity. These antibodies are to the VP4 or VP7 surface antigens)

Front 18

What are the characteristics of the Astrovirus genome?

Is it enveloped?

What is it's shape?

Back 18

ssRNA
(+) sense

Non-enveloped

Icosahedral capsid

Front 19

Which virus is similar to rotavirus, but milder and usually self-limiting?

Back 19

Astroviruses.

Front 20

What is the most common Astrovirus serotype?

Back 20

HAstV-1
(* 8 known serotypes)

Front 21

Which individuals do Astroviruses most commonly infect?

Back 21

Children <2 yrs old, elderly, and immunodeficient

Front 22

How is the Astrovirus transmitted?

Back 22

Person-to-person (fecal-oral)

Front 23

Does astrovirus result in mild or severe dehydration?

Back 23

Mild dehydration

*Astrovirus induced diarrhea is not as severe as rotavirus, and typically does not require hospitalization

Front 24

Which bacteria releases toxins that cause the release of serotonin into the intestine, resulting in projectile vomiting?

Back 24

Staphylococcus aureus.

Front 25

Symptoms of Staph food poisoning usually occur after how many hours?

What symptoms are typical?

Back 25

1-4 hours

*Projectile vomitting (diarrhea almost never occurs)

Front 26

What is the most common cause of food poisoning in the U.S?

Back 26

Staph. aureus

Front 27

How can you distinguish a Staph. aureus infection from a Norwalk infection based on symptoms?

Back 27

Both will cause vomitting, but only Norwalk will cause diarrhea

Front 28

Which type of bacillus cereus food poisoning has a quicker onset (2-3 hours) and is often obtained through starchy foods?

Back 28

Type I

(heat-stable toxin)

Front 29

Type II bacillus cereus food poisoning is often due to the ingestion of what types of foods?

How long does it normally take for symptoms to arise?

Back 29

Meats or vegetables

10-12 hours for symptoms

Front 30

Which type of bacillus cereus has a heat-labile toxin?

Back 30

Type II

Front 31

What type of symptom is seen in bacillus cereus food poisoning?

Back 31

Vomiting (often projectile)

Front 32

Which bacteria causes abdominal cramping and watery diarrhea within 8-12 hours of ingesting infected food such as meat, poultry, sauces, and gravy?

Back 32

Clostridium perfringes
(very similar to Type II bacillus cereus)

Front 33

What is the virulence factor associated with Clostridium perfringes?

Back 33

Enterotoxin (CPE)

Front 34

Type I bacillus cereus can be confused with what other infectious food poisoning?

Back 34

Staphylococcal aureus.

Front 35

Which bacteria is most often found in people that have ingested home-canned vegetables or sausage?

Back 35

Clostridium botulinum.

Front 36

Which bacteria causes the only food born disease that takes more than 12 hours from ingestion to symptom onset?

Back 36

Clostridium botulinum.

Front 37

What are some symptoms associated with Clostridium botulinum?

What is death typically caused by?

Back 37

1. Blurred vision
2. Bilateral flaccid paralysis

*Death caused by respiratory failure

Front 38

What is the effect of botulinum antitoxin?

Back 38

Antitoxin does not reverse paralysis, but it does arrest its progression.

Front 39

What type of therapy is indicated for most food poisonings?

Back 39

Supportive therapy (oral hydration, or in severe cases IV fluid and electrolyte placement).

*Only exception is Clostridium botulinum-- Must administer Botulinum antitoxin as soon as possible

Front 40

In general, what type of symptoms are caused by bacterial agents of small intestine disease?

Back 40

Large volume, watery diarrhea

Front 41

In general, what type of symptoms are caused by bacterial agents of large intestine disease?

Back 41

Small volume, bloody diarrhea

Front 42

Which bacteria are responsible for "traveler's diarrhea?"

Back 42

E.coli
(ETEC, EAEC)

Front 43

How does ETEC cause watery diarrhea?

Back 43

Release heat-stable and heat-labile toxin

Front 44

How does EAEC cause watery diarrhea?

Back 44

EAEC binds to the mucosal cells of the intestine and then kills the cells

Front 45

How does EPEC cause watery diarrhea?

Back 45

EPEC injects proteins into the mucosal epithelial cells

Front 46

Which type of E.coli does not produce a toxin?

Back 46

EPEC
(Instead of a toxin, it injects proteins into mucosal epithelial cells which lead to watery diarrhea)

Front 47

Which type of E.coli (that causes small intestinal disease) has the shortest duration of disease?

Back 47

ETEC (~24 hours)

EAEC lasts for several days

Front 48

Which type of E.coli causes a mild disease and is typically seen in children 6 months of age or less.

Back 48

EPEC

Front 49

Which serotype and biotype of Vibrio choleral causes pandemics?

Back 49

Vibrio cholera serotype O1, biotype El Tor

Front 50

What are the symptoms caused by Vibrio cholera?

Back 50

Symptoms are due to DEHYDRATION
(massive watery diarrhea)

Front 51

What are the two components of the Vibrio cholera toxin?

Back 51

5 "B" subunits-- bind to GM1 ganglioside of intestinal epithelial cell surface
1 "A" subunit-- activates uncontrolled production of cAMP--> results in secretion of Na and Cl, leading to water loss

Front 52

Which bacterial infection results in a sudden onset of massive diarrhea, sometimes described as "rice water stool?"

Back 52

Vibrio cholera
(watery diarrhea w/ flakes of mucus and epithelial cells)

Front 53

Does Vibrio cholera invade epithelial cells?

Back 53

No--the mucus remains intact
V. cholera releases a toxin that increases cAMP production --> results in secretion of Na+,Cl- followed by water.
It does not directly damage intestinal cells.

Front 54

Will leukocytes be present in stool from an individual infected by Vibrio cholera?

Back 54

No

Front 55

What is the treatment for Vibrio cholera?

Back 55

Fluid and electroytes--oral or IV

Antibiotics used only in severe cases.

Front 56

Vibrio cholera can sometimes be confused with an infection from what other bacteria?

Back 56

ETEC

Front 57

What are the two serogroups of Shigella?

Which is most common?

Back 57

B- Shigella flexneri
D- Shigella sonnei <--- Most common

Front 58

Shigellosis usually affects what type of individuals?

Back 58

Children <5 yrs

Front 59

What are the 3 biological activities of Shiga-toxin?

Back 59

1. Neurotoxic
2. Cytotoxic
3. Enterotoxic

Front 60

The Shiga-toxin consists of two subunits. What are the functions of these subunits?

Back 60

B- serves as binding factor
A- inactivates the 60S ribosomal subunit, inhibiting protein elongation

*Results in direct cell death

Front 61

What are the symptoms of Shigellosis?

Back 61

1. Initially, watery diarrhea and fever
2. Diarrhea becomes frequent, but low volume (contains blood and mucus)
3. Severe pain on defecation

Front 62

How fast is the recovery from Shigellosis?

Back 62

Spontaneous recovery 2-7 days after onset

Front 63

Why is antibiotic therapy contraindicated for shiga toxin producing bacteria?

Back 63

Antibiotics increase the risk of HUS (hemolytic uremia syndrome)

*Do NOT administer for Shigella or EHEC infections

Front 64

Which type of Salmonella results in a self-limiting gasterenteritis?

Back 64

Salmonella enterica

Front 65

Describe the course of a Salmonella typhi infection during the first week. (How does the bacteria infect?)

Back 65

1. Penetration of intestinal wall and infection of regional lymph nodes
2. Invasion of the bloodstream
3. Ingestion of the organism by monocytes

*In the mean time, the infected individual will develop a fever, malaise, general aches/pains, and constipation.

Front 66

How do some people become carriers of Salmonella typhi?

Back 66

The bacteria infects the biliary tree and can re-infect the intestinal tract from the gall bladder.
(bacteria is released with bile)

Front 67

Rose spots are pathognumonic for which bacterial infection?

Back 67

Salmonella typhi

Front 68

List 4 virulence factors of Salmonella typhi.

Back 68

1. Invasiveness (penetrates epithelial lining of small intestine)
2. Antiphagocytic surface antigen (Vi)
3. Resists intracellular killing
4. Endotoxin

Front 69

How can you diagnose an S. typhi infection?

Back 69

Labratory diagnosis: isolation of S. typhi from blood

(Stool specimen will only provide presumptive evidence)

Front 70

In general, what types of vaccines are available for S. typhi?

Back 70

1. Vaccine based on Vi antigen
2. Live, attenuated strain

Front 71

Which bacterial infection results in acute enteritis and bacterial gastroenteritis?

Back 71

Campylobacter jejuni

Front 72

What is the difference in epidemiology between Campylobacter jejuni outbreaks in the summer versus spring/fall outbreaks?

Back 72

Summer--> usually due to improperly cooked poultry

Spring/fall--> usually due to contaminated milk

Front 73

Does campylobacter jejuni have a relatvely low or high infective does?

What about Salmonella typhi?

Back 73

Campylobacter jejuni--> low infective dose

Salmonella typhi --> high infective dose

Front 74

What are the symptoms of Campylobacter jejuni infections?

Back 74

Dysentery with blood and pus in the stool
(Also can mimic acute appendicitis--RLQ pain)

Front 75

T or F.

Campylobacter jejuni infections are usually self-limiting.

Back 75

TRUE.

Front 76

At what temperature does Campylobacter jejuni grow best at?

Back 76

42*C

Front 77

Which type of E.coli is the most common cause of Enterohemmorhagic E.coli infections?

Back 77

EHEC
E.coli 0157:H7

Front 78

What is the severe sequelae associated with EHEC?

Are antibiotics indicated for treatment?

Back 78

HUS (hemolytic uremic syndrome)

Do NOT give antibiotics!

Front 79

Hemolytic uremic syndrome usually affects which individuals?

What are the results of this syndrome?

What is the treatment?

Back 79

Usually affects children <5 yrs old.

RBC destruction
Kidney failure

Treatment: blood transfusion

*Sequele seen in Shigellosis or EHEC

Front 80

Which two life-threatening illnesses can result from E.coli O157:H7?

Back 80

1. Hemolytic uremic syndrome-- kids
2. Disease of CNS -- adults

Front 81

E.coli O157:H7 infections lack a certain symptom that makes it unique out of the the other organisms that cause dysentery. Which symptom is this?

Back 81

Fever is NOT present

Front 82

Pseudomembranous colitis can be a result of what type of bacterial infections?

Back 82

Clostridium difficile

Front 83

Which bacteria is often responsible for nosocomial infections?

Back 83

Clostridium difficile

Front 84

Which bacteria can survive at low temperatures and are often transmitted in soft cheeses, processed meats, and ready-to-eat foods?

Back 84

Listeria monocytogenes

Front 85

Which bacteria can travel to the nervous system, resulting in headaches, stiffness of neck, loss of balance, confusion, and convulsions?

Back 85

Listeria monocytogenes.

Front 86

List 4 bacteria associated with food poisoning.

Back 86

1. Staphylococcus aureus
2. Bacillus cereus
3. Clostridium perfringens
4. Clostridium botulinum

*All Gram (+)

Front 87

List 2 bacterial agents that cause small intestine disease.

Back 87

1. E.coli (ETEC, EAEC, EPEC)
2. Vibrio cholera

Front 88

List 6 bacterial agents that cause large intestine disease.

Back 88

1. Shigella (flexneri, sonnei)
2. Salmonella (enterica, typhi)
3. Campylobacter jejuni
4. E.coli (EHEC, EIEC)
5. Clostridium difficile
6. Listeria monocytogenes

Front 89

List the gram (-) bacterial agents that cause large intestine disease.

Back 89

1. Shigella
2. Salmonella
3. E.coli
4. Campylobacter jejuni

Front 90

Which large intestine bacterial infections should NOT be treated with antibiotics?

Back 90

1. Shigella
2. EHEC (Enterohemmorhagic E.coli)

Front 91

Which gastroenteritis-causing bacteria can be transferred to humans by reptiles, such as turtles?

Back 91

Salmonella enterica