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Microbiology Final > Chapter 20: Infectious Diseases Affecting the Gastrointestinal Tract > Flashcards

Chapter 20: Infectious Diseases Affecting the Gastrointestinal Tract Flashcards

1
Q

GI Tract Defenses

A
  • intestinal surfaces coated with layer of mucus
  • IgA found on most surfaces
  • peristalsis
  • saliva
    • lysozyme and lactoferrin
  • stomach acid
  • bile
  • appendix
  • GALT
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2
Q

GALT

A
  • tonsils and adenoids in the oral cavity and pharynx
  • small areas of lymphoid tissue in the esophagus
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3
Q

How does E. coli assist with digestion?

A

Synthesizes vitamin K

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4
Q

Which of the following types of organisms are not considered normal biota of the gastrointestinal system?

A.bacteria
B.archaea
C.fungi
D.protozoa
E.None of the choices is correct.

A

B. archaea

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5
Q

Causative agents of chronic diarrhea

A
  • E. coli
  • Cyclospora
  • Giardia
  • Entamoeba
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6
Q

Causative agents of food poisoning

A
  • Staphylococcus aureus
  • Bacillus cereus
  • Clostridium perfringens
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7
Q

Causative agents of dental carries and periodontitis

A
  • Streptococcus mutans
  • Scardovia wiggsiae
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8
Q

Causative agent of mumps

A

Paramyxovirus

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9
Q

Causative agent of Salmonella

A
  • S. enteritica
    • other bacteria may cause also
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10
Q

Properties of Salmonella

A
  • ferment glucose; Motile
  • can survive outside the host in hospitable environments, fresh water and freezing temperatures
  • resistant to chemicals
  • Most strains come from animals
  • Salmonella are normal intestinal biota in cattle, poultry, rodents, and reptiles
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11
Q

Signs and Symptoms of Salmonella

A
  • Severe forms of salmonellosis can include
    • elevated body temperatures
    • septicemia
  • Milder forms of salmonellosis
    • Vomiting
    • diarrhea
    • mucosal irritation
    • blood can appear in the stool
  • death is infrequent except in debilitated
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12
Q

Illnesses caused by salmonella

A
  • Typhoid fever
    • caused by the typhi variant. Salmonella typhi infects humans exclusively
  • Gastroenteritis
    • caused by paratyphi, hirschfeldii,

and typhimurium

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13
Q

Salmonella’s virulence factors

A
  • its ability to adhere effectively to gut mucosa
  • endotoxin
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14
Q

Prevention and Treatment of Salmonella

A
  • Avoid contact with bacteria
  • trimethoprim-sulfamethoxazole (TS)
    • when disease is severe
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15
Q

Salmonella has a high ID50, meaning…

A

A lot of organisms must be ingested for disease to result

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16
Q

Salmonella commonly found in

A

milk and eggs

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17
Q

Shigella bacteria characteristics

A
  • gram-negative rods
  • non motile
  • non-spore-forming
  • primarily human parasites, but can infect Apes
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18
Q

Signs and symptoms of Shigella

A
  • Frequent, watery stools
  • Fever
  • Intense abdominal pain
  • Nausea and vomiting are common
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19
Q

Dysentery

A
  • diarrhea containing blood
  • Mucus from the GI tract is also present in the stools
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20
Q

Virulence Factors of Shigella

A
  • Shigella invades the villus cells of the large intestine rather than the small intestine
  • Causes inflammatory response
  • Enterotoxin
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21
Q

Shiga Toxin

A
  • Produced by Shigella dysenteriae
  • may be responsible for more serious

damage to the intestine

  • also causes systemic effects, including injury to nerve cells
22
Q

Transmission of Shigella

A
  • Oral route
  • direct person-to-person
  • sanitation, malnutrition, and crowding
23
Q

True or False: Shigella can establish a chronic carrier condition in some people that can last several months

A

True

24
Q

Prevention and Treatment of Shigella

A
  • Good hygeine
  • trimethoprim-sulfamethoxazole (TS)
25
Q

most virulent enterohemorrhagic E. coli or

EHEC

A

E. coli O157:H7

26
Q

Signs and Symptoms of E. coli O157:H7

A
  • Mild gastroenteritis, Fever, Bloody diarrhea
    • 10% of patients develop severe hemolytic anemia in kidney and can cause kidney damage and failure
    • Neurological symptoms such as blindness, seizure, and stroke
27
Q

Virulence factors of E. coli O157:H7

A
  • Shiga toxin
    • interrupts protein synthesis on target cells
      lesions in large intestines & produce bloody diarrhea
28
Q

Transmission of E. coli O157:H7

A
  • Most common mode of transmission for EHEC is ingestion of contaminated or undercooked beef
    • other foods and beverages can be contaminated
    • any farm product can become contaminated with cattle feces
  • Products eaten raw such as lettuce, vegetable, and apples used in unpasteurized cider are particularly problematic
29
Q

Culture and Diagnosis of E. coli O157:H7

A

stool culture or with ELISA or PCR

30
Q

Prevention and Treatment of E. coli O157:H7

A
  • never to eat raw or rare hamburger and to wash raw vegetables
  • supportive therapy, including plasma

transfusions to dilute the toxin in the blood is the only option

* antibiotics may increase pathology
31
Q

Campylobacter

A

Considered to be the most common bacterial

cause of diarrhea in the U.S

32
Q

Signs and symptoms of Campylobacter

A
  • Frequent, watery stools
  • Fever
  • Vomiting
  • Headaches
  • Severe abdominal pain
    • Symptoms may last longer than 2 weeks
33
Q

Causative agents of Campylobacter

A

Campylobacter jejuni

34
Q

Transmission of Campylobacter

A
  • ingestion of contaminated beverages and food
  • water, milk, meat, and chicken
35
Q

Yersinia

A
  • Gram-negative bacteria
  • includes the species Yersinia pestis,
    • cause of the plague
36
Q

Species of Yersinia that cause GI tract diseases

A
  1. Y. enterocolitica
  2. Y. pseudotuberculosis
37
Q

GI Yersinia is often mistaken for what?

A

appendicitis

38
Q

Clostridium difficile

A

Gram-positive endospore forming rod as normal flora

39
Q

Signs and Symptoms of Clostridium difficile

A
  • Diarrhea
  • severe cases exhibit
    • abdominal cramps
    • Fever
    • colon is inflammed and gradually sloughs off loose, membranelike patches called pseudomembranes
    • if the condition is not stopped, perforation of the cecum and death can result
40
Q

Virulence factors of Clostridium difficile

A
  • Superinfection
    • opportunistic
  • Enterotoxin
    • necrosis
41
Q

Treatment of Clostridium difficile

A
  • Replacement of lost fluids and electrolytes
  • antibiotics in severe cases
42
Q

Causative agent of Cholera

A

Vibrio cholerae

43
Q

Signs and symptoms of cholera

A
  • Abrupt symptoms of vomiting followed by copious, watery feces called secretory diarrhea
    • contains flecks of mucus and is described as “rice water stool”
  • Oodles of fluid loss
    • sometimes up to 50% of body weight
  • Potassium depletion
  • If cholera is left untreated, death can occur in less than 48 hours & mortality rate approaches 55%
44
Q

Virulence factors of cholera

A
  • Cholera toxin
    • fluid loss
45
Q

Transmission of cholera

A
  • Seasonal
  • Water and food
46
Q

Prevention and Treatment of Cholera

A
  • Proper sewage treatment
  • Vaccines available to travelers
  • Prompt replacement of fluids and electrolytes
  • Oral antibiotics: trimethoprim-sulfamethoxazole (TS)
47
Q

GI Viruses

A
  • Rota virus
  • Adenoviruses
  • noroviruses (Norwalk viruses)
  • astroviruses
48
Q

Transmission of GI viruses

A
  • fecal-oral
  • food contamination
49
Q

Food poisoning should be suspected when…

A
  • severe nausea and frequent vomiting accompanied by diarrhea
  • patient reports that companion also has similar symptoms after eating the same thing
  • onset within last 1-6 hours
50
Q

Bacteria that produce the food poisoning toxin

A
  • Staphylococcus aureus
  • Bacillus cereus
  • Clostridium perfringens

Microbiology Final (12 decks)

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