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Applied Pathophysiology > Gastrointestinal Infections (GIIs) > Flashcards

Gastrointestinal Infections (GIIs) Flashcards

1
Q

What does a “normal” or “healthy GI tract have?

A

is enriched with MICROBIOTA
* BACTERIA (MAJORITY)
* archaea
* fungi
* viruses
* protozoans (least?)

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2
Q

What is the size of an average adult GI tract surface?

A

average adult GI tract
surface is 400 m2

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3
Q

How much does gut microbiota weight account for?

A

accounts for 1-2 kg of total body weight

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4
Q

How much bacteria is located in the GI tract?

A

95%

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5
Q

What help increase SA in the GI tract?

A

villi

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6
Q

What does Gastrointestinal infections (GII) and enterotoxigenic poisonings result in?

A

INFLAMMATION of the GI TRACT

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7
Q

What are inflammation-induced vomiting & diarrhea responsible for?

A

responsible for much of the MORBIDITY and MORTALITY of GIIs

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8
Q

What is the difference b/t a healthy and a compromised barrier?

A

Healthy barrier ↓ inflammation (thick mucosal barrier)

Compromised barrier ↑ inflammation

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9
Q

What is the definition of diarrhea?

A

a decrease in consistency of bowel movements (ie. unformed stool) and an increase in frequency of stools to > 3 per day

2 types: acute or persistent

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10
Q

What is Acute diarrhea?

A

lasts 14 days or less

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11
Q

What is Persistent diarrhea?

A

lasts 14 days or longer (need more fluid replacement therapies)

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12
Q

What are GIIs caused by?

A

caused by a wide variety of VIRAL, BACTERIAL, fungal, protozoan, and parasitic pathogens
* Common GIIs are viral and bacterial→our focus in class

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13
Q

What is the epidemiology of Acute gastroenteritis?

A

inflammation of the GI tract
* 25% of all hospitalizations and 85% of all mortality associated with diarrhea involved the ELDERLY (age > 60 yrs)
* other groups at risk: include CHILDREN, travelers (ex: swimming in non chlorine waters), campers, patients in chronic care facilities, and immunocompromised patients.

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14
Q

What are Acute gastroenteritis & its resulting diarrhea caused by?

A

caused by ALTERED MOVEMENT OF IONS AND WATER in the INTESTINE resulting in increased colonic secretion

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15
Q

What is normally what happens with the GI tract?

A

Normally, the GI tract absorbs a tremendous amount of fluids and electrolytes→allowing only 100 to 200 mL OF FLUID TO BE EXCRETED IN THE STOOL DAILY

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16
Q

What is the epidemiology of Acute Infectious diarrhea?

A

Causes dehydration and is the 2nd LEADING CAUSE of
mortality in CHILDREN YOUNGER THAN 5 YEARS OF AGE
* Globally, 1.7 billion cases of infectious diarrhea/yr and cause over 2 million deaths
- YOUNGER CHILDREN (< 1 yr) have the highest risk of death from acute dehydrating diarrhea

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17
Q

What is the etiology of GIIs?

A

ETIOLOGIC AGENTS ARE RARELY IDENTIFIED due to the infrequent collection of stool samples, or inability of many laboratories to detect the full range of pathogenic organisms

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18
Q

What are the 2 main diarrheal forms?

A
  1. Watery diarrhea
  2. Dysenteric (bloody) diarrhea
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19
Q

Which of the main diarrheal forms is is the MOST COMMON; 90-95% of all GII patients?

A

Watery diarrhea

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20
Q

Which of the main diarrheal forms results in SEVERE DEHYDRATION, acidosis, shock, and electrolyte imbalance

A

Watery diarrhea

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21
Q

Which of the main diarrheal forms have Virulence factors include toxins that reduce host water adsorption?

A

Watery diarrhea

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22
Q

Which of the main diarrheal forms are LESS COMMON; 5-10% of all GII patients?

A

Dysenteric (bloody) diarrhea

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23
Q

Which of the main diarrheal forms results in MILD DEHYDRATION, tenesmus (continual bowel evacuation), rectal prolapse (organ misalignment), seizures?

A

Dysenteric (bloody) diarrhea

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24
Q

Which of the main diarrheal forms if untreated may result in BACTEREMIA OR SEPSIS?

A

Dysenteric (bloody) diarrhea

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25
Q

Which of the main diarrheal forms have VIRULENCE FACTORS that promote mucosal and epithelial INVASION?

A

Dysenteric (bloody) diarrhea

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26
Q

What do both diarrheal forms have symptoms of?

A

vomiting, abdominal pain, cramping, fever

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27
Q

Which of the main diarrheal forms have < 10 stools/day,
NO OCCULT BLOOD, pH 5-7.5, Low or no polymorpho- nuclear cells?

A

Watery

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28
Q

Which of the main diarrheal forms transmission is contaminated food or water with animal or human feces;
Duration: 1-4 days?

A

Watery

29
Q

Which of the main diarrheal forms have the following etiological agents?

Vibrio cholera,
E.coli (Enterotoxigenic (ETEC), Enteroinvasive (EIEC), Enteropathogenic (EPEC), Enteroaggregative (EAEC)) Rotavirus
Norovirus

A

Watery

30
Q

Which of the main diarrheal forms have > 10 stools/day, BLOODY; occult blood positive, pH 6-7.5,
High polymorpho- nuclear cells

A

Dysenteric

31
Q

Which of the main diarrheal forms transmission is contaminated food, water, or contact with infected animals; fecal-oral
Duration: 3-7 days

A

Dysenteric

32
Q

Which of the main diarrheal forms have the following etiologic agents?

Shigella spp,
E.coli (Enterohemorrhagic (EHEC))
Salmonella spp. Campylobacter spp., Yersina spp.,
Clostridium difficile

A

Dysenteric

33
Q

What are viruses now recognized as?

A

the LEADING GLOBAL CAUSE of infectious diarrhea (pre- & post COVID)

34
Q

What do Noroviruses account for?

A

(NoV; aka Norwalk-like viruses) account for < 90% OF VIRAL GASTROENTERITIS among ALL AGE groups and 50% of outbreaks worldwide

35
Q

What do the Rotavirus account for?

A

is the MOST COMMON cause of infectious diarrhea globally; PRIMARILY AFFECTS CHILDREN < 5 yrs

36
Q

What do other viral GIIs causing diarrhea include?

A

astrovirus, enteric adenovirus, pestivirus, coronavirus, and enterovirus

37
Q

What are both Noroviruses & Rotaviruses?

A

Both are non-enveloped (capsid) viruses that are resistant to disinfectants

38
Q

What is the Antiviral treatment?

A
  • no single antiviral is completely successful in treating/ curing enteric viral infections→many in development
  • the infection resolves within 3-7 days WITH ADEQUATE SUPPORTIVE CARE (ie. ORST)
39
Q

What is the Vaccine treatment for Viral Gastroenteritis?

A
  • NO vaccines exist to treat NOROVIRUS*
  • ROTAVIRUS vaccine: RotaTeq®
  • Infants (2-6 months):
  • Does not protect against other viral gastroenteritis causes
  • Oral rehydration solution therapy (ORST) is the RECOMMENDED treatment for mild to moderate GIIs
40
Q

Vibrio cholerae
(Cholera)

Virulence factors:

Etiology:

A

Virulence factors:
Heat-labile LT enterotoxin = Ctx toxin
and Adhesins

Etiology:
Endemic on the Indian subcontinent and sub-Saharan Africa→watery diarrhea

41
Q

Enterotoxigenic E.coli (ETEC)

Virulence factors:

Etiology:

A

Virulence factors:
Heat-labile LT and Heat-stable (ST) enterotoxins

Etiology: Most common cause of traveller’s diarrhea and outbreaks→watery diarrhea

42
Q

Enterohemorrhagic E.coli (EHEC), Shigella spp. (Shigellosis)

Virulence factors:

Etiology:

A

Virulence factors:
Shiga toxin (Stx)

Etiology: Causes watery dysenteric diarrhea (1 to 5 days) in 80% of patients→ hemorrhagic colitis/ dysentery

43
Q

Enteroinvasive E. coli (EIEC)

Virulence factors:

Etiology:

A

Virulence factors: Invasins

Etiology: Most common in children from developing countries→watery

44
Q

Enteropathogenic E. coli (EPEC)

Virulence factors:

Etiology:

A

Virulence factors: Adhesins

Etiology: Most common in children from developing countries→watery

45
Q

Enteroaggregative E. coli (EAEC)

Virulence factors:

Etiology:

A

Virulence factors: hemolysin toxin and EnteroAggregative ST-like (EAST) toxin

Etiology: Most common cause of persistent watery diarrhea (< 14 days) in immuno-compromised patients

46
Q

Campylobacter jejuni Yersina spp, Salmonella enterica sv. Typhi

Virulence factors:

Etiology:

A

Virulence factors: cytolethal distending toxin (Cdt)
and Invasins

Etiology: Common animal microflora transmitted to humans→dysentery diarrhea

47
Q

Clostridioides difficile

Virulence factors:

Etiology:

A

Virulence factors: TcdAB toxin

Etiology: Commonly occurs in patients after prolonged antibiotic or proton pump therapies→dysentery and toxic megacolon

48
Q

What are the Virulence factors altering intestinal function?

A
  • Adhesins
  • Invasins
  • Toxins
49
Q

Adhesins→

A

allow bacteria to adhere to host cells (e.g. pili, lipopolysaccharides)

50
Q

Invasins→

A

bacterial proteins that damage host cell membranes to allow bacterial cell entry and invasive spread

51
Q

Toxins→

A

substances that kill host cells by disrupting their normal function (e.g. Cdt, TcdAB, Hemolysin)
* Enterotoxins→toxins that alter the normal ion flux (Cl-, Na+, K+) and lining function of host intestinal cells (e.g. LT/ Ctx, Stx, ST/ EAST)

52
Q

Due to the low yield, stool cultures are…

A

NOT recommended in most mild to moderate watery diarrhea

53
Q

STOOL CULTURES are only recommended for:

A
  • DYSENTERIC diarrhea
  • PERSISTENT DIARRHEA in immunocompromised patients:
  • Patients < 65 years + comorbidity,
  • Neutropenia: abnormally low number of WBC neutrophils
  • HIV infection
  • diarrhea where an OUTBREAK is suggested
54
Q

What is a general complication that often occurs long after GIIs, especially with dysentery and toxin-mediated dysentery?

A

post-infectious irritable bowel syndrome (IBS)

55
Q

What are lab tests (visual, blood, & stool based)?

A
  • Blood pressure (BP), heart rate (HR), respiratory rate (RR), WEIGHT, O2-saturation, abdominal distention*
  • WHITE BLOOD CELL COUNT (WBC) and serum creatinine (SCr) levels, and polymorphonuclear (PMN) cell microscopy
  • STOOL SAMPLE to be tested for toxins, or other bacterial enterotoxins→PCR OR IMMUNOCHEMICAL ASSAYS
  • COLONOSCOPY OR ENDOSCOPY→if severe, recurrent, or persistent diarrhea is present (C. difficile infections)
  • RADIOGRAPHIC ABDOMINAL IMAGING (X-ray, Magnetic Resonance Imaging) if there is concern for ileus (blockage of intestine) or megacolon (enlarged intestines and colon)
56
Q

What are Clostridium difficile infections (CDI) treatments?

A
  • COLONOSCOPY: raised white and yellowish plaques form in the colon, and the surrounding mucosa may be inflamed
  • ranges from mild diarrhea to life-threatening TOXIC MEGACOLON and PSEUDOMEMBRANOUS ENTEROCOLITIS
  • FECAL TRANSPLANTS are becoming a POPULAR TREATMENT for CDIs
  • HEALTHY DONOR FECES/ MICROBIOTA→oral, pill or suppository forms
57
Q

What are Diarrhea treatment?

A
  • Fluid replacement
  • Weight loss monitoring
  • anti-diarrheals:
  • oral rehydration solution (ORS) therapy:
  • cholera infections
58
Q

What is the Fluid replacement treatment?

A

Fluid replacement is the cornerstone of therapy for dehydration due to diarrhea regardless of etiology
* WEIGHT LOSS MONITORING: most reliable means of determining the extent of water loss

59
Q

What is the anti-diarrheals treatment?

A

diphenoxylate/atropine and LOPERAMIDE act by thickening stool
* Used for acute and chronic diarrhea→usage may mask signs of more severe infection and increase toxin damage of GI tract

60
Q

What is the oral rehydration solution (ORS) therapy?

A

ORS includes carbohydrates (typically glucose), sodium, potassium, chloride, and water (ORS = <250 mOsmol/L)
* CHOLERA INFECTIONS: polymer-based ORS may be more efficacious and contains rice, wheat, sorghum, or maize →slower release of glucose

61
Q

What is the treatment for mild, self-limiting acute gastroenteritis?

A

a diet of oral fluids and easily digestible foods is recommended
* Dairy products and high fibre foods should be AVOIDED

62
Q

What is the treatment for severe dehydrating watery and dysenteric diarrhea?

A

intravenous (IV) rehydration therapy, antibiotics, and/or anti-diarrheal treatments are needed
* IV Lactated Ringer solution is preferred over saline→lactated ringer assists in correcting METABOLIC ACIDOSIS

63
Q

What should be avoided in the treatment of dehydration?

A

Clear fluids, such as soft drinks, sweetened fruit drinks, chicken broth, and sports drinks should be avoided in the treatment of dehydration
* These hyperosmolar solutions may cause an OSMOTIC DIARRHEA

64
Q

What is the indiscriminate use of antimicrobial therapy?

A
  • Increases ANTIMICROBIAL RESISTANCE & DRUG SIDE EFFECTS
  • Increases threat of SUPERINFECTIONS due to LOSS OF FLORA
65
Q

What is the antibiotic therapy recommended for?

A
  • severe cases of diarrhea
  • moderate-to-severe cases of traveler’s diarrhea
  • most cases of febrile (feverish) dysenteric diarrhea
  • culture-proven bacterial diarrhea
66
Q

What is the Antimicrobial therapy not recommended in?

A

in EHEC diarrhea as it may increase hemolytic uremia syndrome (HUS) risk

67
Q

What is the Antimicrobial & Vaccine therapies dependent on?

A
  • Dependent on infectious species (suspected or confirmed)
  • Watery, dysenteric and traveler’s diarrhea
  • ANTIBIOTICS: AZITHROMYCIN, cefotaxime, ciprofloxacin, rifaximin,
    doxycycline, tetracycline
  • CDI: metronidazole and vancomycin antibiotics
68
Q

What are the vaccines therapies?

A

Can prevent GIIs caused by ETEC (LT toxin) and Cholera (Ctx)→prevents traveler’s diarrhea
* DUKORAL (whole killed cell V. cholerae + Ctx toxin)
* SHANCHOL (whole killed cell V. cholerae only)
* Short lived immunity 6 months→booster up to 5 years from immunization

Applied Pathophysiology (34 decks)

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