Gastrointestinal Infections Flashcards
1
Q
Obtain a good medical history, what information is pertinent?
A
Certain sexual practices Hospitalizations LTC facilities Child care facilities Foodborne or waterborne International travel Antimicrobial agents Immunocompromised host Animal exposure
2
Q
Diarrhea defined:
A
↓in the consistency of bowel movements (i.e. unformed stool); ↑ in frequency of stools (> 3 per day)
NOTE:
Infectious diarrhea
Vomiting and diarrhea are responsible for much of the morbidity & mortality
3
Q
Acute diarrhea
A
<14 days duration
4
Q
Chronic diarrhea
A
≥ 14 days duration
5
Q
Acute infectious diarrhea (I.D.):
A
Globally
-Younger children (< 5 yrs) are at higher risk of death from acute dehydrating diarrhea
In the United States:
-Highest risk of mortality is the elderly (as opposed to children, in the developing world)
Others at risk: travelers, campers, pts in chronic care facilities, military personnel stationed abroad, immunocompromised pts
6
Q
Watery diarrhea vs. dysentery
A
Diarrhea is a condition that involves the frequent passing of loose or watery stools.
Dysentery is an intestinal inflammation, especially in the colon, that can lead to severe diarrhea with mucus or blood in the feces.
7
Q
Watery diarrhea:
- appearance
- volume
- number per day
- reducing substances
- pH
- occult blood
- fecal PMNs
A
- watery
- increased: ++/+++
- < 10
- 0 to +++
- 5 - 7.5
- negative
- absent or few
8
Q
Dysentary:
- appearance
- volume
- number per day
- reducing substances
- pH
- occult blood
- fecal PMNs
A
- bloody
- increased: +/++
- > 10
- 0
- 6 – 7.5
- positive
- many
9
Q
Watery diarrhea:
Complications
1. dehydration
2. others
A
- could be severe
2. acidosis; shock; electrolyte imbalances
10
Q
Dysentary:
Complications
1. dehydration
2. others
A
- mild
2. tenesmus; rectal prolapse; seizure
11
Q
Watery diarrhea: Etiology
A
Vibrio cholerae
Enterotoxigenic E. coli (ETEC)
Rotaviruses
Noroviruses
12
Q
Dysentary: Etiology
A
Shigella Salmonella Campylobacter spp. Enterohemorrhagic E. coli (EHEC) Yersinia spp. Clostridioides difficile
13
Q
DYSENTERY
(bloody; inflammatory)
Cause:
Signs and Sx:
A
Cause is mostly bacterial (i.e. EHEC, Shigella, Salmonella, & Campylobacter)
Mucoid stool ± blood
Lower abdominal cramping w/ pain
Fever is more common
Colon is affected
Colonic ulceration occurs in addition to infection of upper epithelial cells
Cells are attacked and destroyed
Antimicrobials can eradicate the pathogen and stop the inflammation
Major systemic complications are possible
Almost always requires antibiotic treatment (IV antibiotics may be needed). EXCEPT for EHEC do NOT use antibiotics in EHEC!!
14
Q
WATERY DIARRHEA
(enterotoxigenic; noninflammatory)
Cause:
Signs and Sx:
A
Cause is mostly viral (Norovirus & rotavirus > ETEC & Cholera)
Watery stool; no blood or mucous
± Cramping & pain
Fever is uncommon
Small bowel is affected
Infection & targeting of intestinal lumen & upper epithelial cells
No cell death; infection is due to toxins
Antimicrobials don’t eradicate the toxin
Less serious than dysentery; dehydration is major risk
Antimicrobial treatment not needed (oral or IV rehydration may be necessary)
15
Q
Causative Organisms
Watery diarrhea (enterotoxigenic)
Non-invasive:
A
Rotavirus
Norovirus
Enterotoxigenic E. coli
Cholera (not in the U.S.)
16
Q
Causative Organisms
Dysentery (bloody diarrhea)
Invasive
A
Shigella Salmonella Campylobacter Enterohemorrhagic E. coli Yersinia enterocolitica Clostridioides difficile
17
Q
Watery diarrhea:
Norovirus
A
Account for > 90% of viral gastroenteritis among all age groups
Healthcare systems, cruise ships, college dorms
(previously known as Norwalk-like viruses)
18
Q
Watery diarrhea:
Rotavirus
A
Is ubiquitous and infects most children < 5 yrs
After infection, 40% of children are protected against subsequent infection
19
Q
Watery diarrhea: Vibrio cholerae (Cholera)
A
Gram-negative bacillus (similar to enterobacteriaceae)
Toxigenic C. cholerae serogroups 01 or 0139
Severe and voluminous diarrhea (watery diarrhea)
Not common in the U.S. due to sanitation of water systems
20
Q
Watery diarrhea:
Enterotoxigenic E. coli (ETEC)
A
Accounts for ½ of all cases of E. coli diarrhea
Most common cause of traveler’s diarrhea
A common cause of food- and water-associated outbreaks
21
Q
E. coli causing watery diarrhea
Toxin-producing:
A
Enteroaggregative E. coli (EAEC)
Enterotoxigenic E. coli (ETEC)
22
Q
E. coli causing watery diarrhea
Non-toxin-producing
A
Enteroinvasive E. coli (EIEC)
Enteropathogenic E. coli (EPEC)
23
Q
E. coli causing dysentery
Toxin-producing
A
Enterohemorrhagic E. coli (EHEC)
24
Q
Viral Gastroenteritis
Norovirus:
A
All age groups Peak in winter 2-3 days Fecal-oral, food, water, environment Nausea, vomiting diarrhea, abdominal cramps, myalgia
25
Viral Gastroenteritis:
| Rotavirus:
6 months to 2 years
October to April
3-7 days
Fecal-oral, water, food
Nausea, vomiting, diarrhea, fever, abdominal pain, lactose intolerance
26
Bacterial Gastroenteritis: E. coli
Enterotoxigenic
E. coli (ETEC)
Watery
1. Toxin Production?
2. Incubation period
3. Duration
4. Mode of transmission
5. Common symptoms
1. YES
2. 1-3 days
3. 3-4 days
4. Contaminated food or water with human or animal feces
5. Watery diarrhea and abdominal cramping
Responsible for ½ of all E. coli diarrheal illness; common cause of food/water outbreaks
27
Bacterial Gastroenteritis: E. coli
Entero-hemorrhagic
E. coli (EHEC):
Dysentary
1. Toxin Production?
2. Incubation period
3. Duration
4. Mode of transmission
5. Common symptoms
1. YES
2. 3-4 days
3. NR
4. Uncooked beef or unpasteurized milk or juice
5. Gastroenteritis, enterocolitis, sometimes bloody diarrhea and hemolytic-uremic syndrome
28
Bacterial Gastroenteritis:
Vibrio cholerae
1. Incubation period
2. Duration
3. Mode of transmission
4. Common symptoms
1. 2 – 3 days
2. 1 – 3 days
3. Contaminated food or water with human feces usually in areas of inadequate treatment of sewage and drinking water
4. Profuse watery diarrhea, vomiting, and leg cramps; Death can work within hours without treatment
29
Bacterial Gastroenteritis:
Salmonella nontyphoidal
1. Incubation period
2. Duration
3. Mode of transmission
4. Common symptoms
1. 12 – 36 hours
2. 1 – 5 days
3. Contaminated food, water, or contact with infected animals
4. Diarrhea (sometimes bloody), fever, and abdominal cramps
30
Bacterial Gastroenteritis:
Shigella spp.
1. Incubation period
2. Duration
3. Mode of transmission
4. Common symptoms
1. 1 – 3 days
2. 1 – 7 days
3. Fecal-oral contaminated food or water with infected human feces
4. Watery or bloody diarrhea (8-10 stools/day), severe abdominal pain, fever, and malaise
31
Enterohemorrhagic E. coli (EHEC):
| Include strains that include:
Shigatoxigenic Escherichia coli (STEC)
Produces shiga toxin
Causes 50-60% of all EHEC infections
A type of EHEC, E. coli 0157:H7
can cause bloody diarrhea and hemolytic uremic syndrome (anemia and kidney failure)
A minority of the strains cause illness in humans
The strains that DO cause illness in humans are collectively known as Enterohemorrhagic E. coli (EHEC)
Major causes of foodborne illness
32
(Nontyphoid) Salmonella enterica
Gram-negative bacilli
Belongs to the Enterobacteriaceae family
Gastroenteritis is cause by:
- Serotypes Typhimurium and Enteritidis
- In the U.S. the largest burden of Salmonella infection is due to nontyphoidal serotypes
33
Shigella spp.
Produces shigellosis
Associated with poor sanitation or personal hygiene, inadequate water supply, malnutrition, and increased population density
S. sonnei and S. flexneri:
-The most common causes of gastroenteritis in the U.S.
S. dysenteriae type 1 and S. boydii
-Commonly acquired during travel
34
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Watery Diarrhea (Acute Gastroenteritis)
Enterotoxigenic E. coli (ETEC)
```
Produces watery diarrhea due to severe intestinal water secretion
Produces 2 toxins
-Heat-stable toxin (ST); heat-labile toxin (LT)
35
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Watery Diarrhea (Acute Gastroenteritis)
Rotavirus
```
Produces a viral enterotoxin
Induces changes in fluid balance by destroying the epithelial lining of the intestine, and vascular damage and ischemia in villi.
36
Watery Diarrhea (Acute Gastroenteritis)
Altered movement of ions and water, resulting in increased colonic secretion
Classic enteric pathogens that cause watery diarrhea in the U.S.
-V. cholerae, ETEC, rotavirus, and norovirus
37
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Watery Diarrhea (Acute Gastroenteritis)
V. cholerae
```
Produces classical secretory diarrhea due to cholera toxin
Toxin consists of 2 subunits, A and B
Toxin acts along the entire intestinal tract
Net effect of the cholera toxin: fluid secretion exceeds absorptive capacity
38
Inflammatory diarrhea (Dysentery)
Caused by 2 groups of organisms:
1.) Enterotoxin-producing, noninvasive bacteria
Adhere to the mucosa, activate cytokines, stimulate the intestinal mucosa to release inflammatory mediators
39
Inflammatory diarrhea (Dysentery)
Caused by 2 groups of organisms:
2.) Invasive organisms: Campylobacter spp., Salmonella spp., Shigella spp.
Invade the intestinal mucosa to induce an acute inflammatory reaction
Involves the activation of local and systemic cytokines and inflammatory mediators
40
Diarrhea
| Noninflammatory
diarrhea that produces watery diarrhea
41
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Diarrhea
Inflammatory diarrhea (dysentery)
```
Bloody stool and mucous
| Fever is often present
42
Norovirus or ETEC
Mild, self-limiting disease
43
Cholera
Severe, dehydrating diarrhea
44
Diagnosis Stool Culture
Gold Standard = Diarrheal stool sample (i.e., a sample that takes the shape of the container)
- Checks for Salmonella, Shigella, E. coli 0157:H7 (SHEC)
- Checks for Ova and Parasites
Blood Culture
-Septicemia, enteric fever, systemic manifestations, immunocompromised patients, people with high-risk conditions
Molecular techniques
-More sensitive and less dependent than culture on the quality of specimen
Other
-Stool leukocytes, stool occult blood, stool Giardia antigen
45
Complications
Usually arise secondary to dehydration so…
-Treatment focuses on rehydration regardless of the cause
Bacteremia
More common in immunocompromised patients (HIV infection, malignancy, malaria)
46
Complications
| A complication of EHEC
Hemolytic-uremic syndrome (HUS)
Defined by the following triad:
1) Acute renal failure
2) Thrombocytopenia
3) Hemolytic anemia
47
Complications
Shigella infection
Can lead to complication such as:
Seizures, sepsis, toxic megacolon, perforated colon, arthritis, & protein-losing enteropathy
Reiter syndrome
- < 3% with S. flexneri will develop
- Characterized by joint pain, irritation of the eyes, painful urination; chronic arthritis may develop
48
Complications
| Reactive arthritis
Occurs 1-2 weeks after gastroenteritis secondary to S. flexneri, Salmonella spp., C. jejuni, and Y. enterocolitica
Can involve knees, ankles, toes, fingers, wrists etc.
Usually resolves in 1-4 months but may persist in ~10% of patients
49
Complications
| Post infectious irritable bowel syndrome (IBS)
Symptoms (recurrent abdominal pain or discomfort) can last ~3 months following an episode of gastroenteritis or traveler’s diarrhea
50
Treatment: Non-pharmacologic
| General
Prevent dehydration by correcting fluid & electrolyte imbalances
Cornerstone of treatment for all types of diarrhea
51
Treatment: Non-pharmacologic
| Mild cases
Mild cases
| Oral fluids and easily digestible foods
52
Treatment: Non-pharmacologic
| Severe dehydration
Severe dehydrating watery diarrhea & dysenteric diarrhea
- IV rehydration
- Antibiotics and antimotility agents may be needed
53
Treatment: Antimicrobial therapy
| Caution
Indiscriminate use causes resistance
Increased fluoroquinolone resistance in Campylobacter
Multidrug resistance in Salmonella spp.
54
Treatment: Antimicrobial therapy
| When is antibiotic use recommended?
Moderate to severe cases of traveler’s diarrhea
Most cases of febrile dysenteric diarrhea (except EHEC)
Culture-proven bacterial diarrhea
55
Treatment: Antimicrobial therapy
Antibiotic therapy is specifically NOT recommended in EHEC diarrhea as it may increase the risk of hemolytic uremic syndrome (HUS)
56
Treatment: Antimicrobial therapy
General information
Consider susceptibility patterns
Cholera: Azithromycin instead of ciprofloxacin in areas of high fluoroquinolone resistance
57
ABX recommended in severe cases of cholera and ETEC
Cholera
-ABX shorten the duration of diarrhea, decrease fluid loss, and shorten duration of the carrier state
ETEC
-empiric ABX reduce severity and duration of diarrhea
-Short course of fluoroquinolone is the most commonly recommended therapy
-Rifaximin has been effective for ETEC for travel in Mexico
58
Treatment: Antimicrobial therapy
| Cholera
Azithromycin
59
Treatment: Antimicrobial therapy
| ETEC
fluoroquinolone
60
Treatment: Antimicrobial therapy
| ETEC travelers diarrhea
Rifaximin
61
Treatment: Antimicrobial therapy
Enterotoxigenic E. Coli (ETEC)
Children
Azithromycin 10 mg/kg/day PO once daily for 3 days; ceftriaxone 50 mg/kg/day given IV once daily for 3 days
62
Treatment: Antimicrobial therapy
Enterotoxigenic E. Coli (ETEC)
Adults
Ciprofloxacin 750 mg PO once daily x 1-3 days.
Alternatives: rifaxamin 200 mg PO TID x 3 days; azithromycin 1G PO x 1 dose or 500 mg PO once daily x 3 days
63
Treatment: Antimicrobial therapy
Vibrio cholerae 01
Children
Erythromycin 30 mg/kg/day divided every 8 hrs PO x 3 days; azithromycin 10 mg/kg/day PO once daily for 3 days
64
Treatment: Antimicrobial therapy
Vibrio cholerae 01
Aldults
Doxycycline 300 mg PO x 1 day.
Alternatives: tetracycline 500 mg PO QID x 3 days; erythromycin 250 mg PO every 8 hrs x 3 days; azithromycin 500 mg PO once daily x 3 days
65
Treatment: Antimicrobial therapy
General information
Shigellosis:
ABX therapy is reserved for the elderly, immunocompromised patients, children in daycare centers, malnourished children, and healthcare workers
In the U.S. Shigella remains susceptible to fluoroquinolones (FQ)
Azithromycin may be a better choice in other countries
66
Treatment: Antimicrobial therapy
| Nontyphoid Salmonella
Leads to bacteremia in ~8% of healthy adults
High risk patients should be treated with ABX if diagnosis is made
High risk patients include:
- Infants < 1 yrs
- Persons > 50 yrs
- Immunodeficiency (AIDS)
- Sickle cell DZ, vascular abnormalities, chemotherapy induced bowel DZ, prosthetic joints
If the organism is isolated
- Perform resistance treating
67
Treatment: Antimicrobial therapy
Dysenteric Diarrhea
Shigella species
Children
Azithromycin 10 mg/kg/day PO once daily x 3 days; ceftriaxone 50 mg/kg/day given IV once daily for 3 days
68
Treatment: Antimicrobial therapy
Dysenteric Diarrhea
Salmonella nontyphoidal
Children
Ceftriaxone 100 mg/kg/day divided IV every 12 hrs x 7-10 days; azithromycin 20 mg/kg/day PO once daily x 7 days
69
Treatment: Antimicrobial therapy
Dysenteric Diarrhea
Shigella species
Adults
Ciprofloxacin 750 mg PO once daily x 3 days; levofloxacin 500 mg PO once daily x 3 days. Alternatives: azithromycin 500 mg PO once daily x 3 days
70
Treatment: Antimicrobial therapy
Dysenteric Diarrhea
Salmonella nontyphoidal
Adults
Ciprofloxacin 750 mg PO once daily x 7-10 days; levofloxacin 500 mg PO once daily x 7-10 days. Alternatives: azithromycin 500 mg PO once daily x 7 days. For immunocompromised patients, duration should be increased to 14 days for both fluoroquinolones and azithromycin
71
Treatment: Antimicrobial therapy
First choice antibiotic in ADULTS
ETEC
Ciprofloxacin 750 mg PO once daily x 1-3 days
72
Treatment: Antimicrobial therapy
First choice antibiotic in ADULTS
Shigella spp.
Ciprofloxacin 750 mg PO once daily x 3 days
73
Treatment: Antimicrobial therapy
First choice antibiotic in ADULTS
Salmonella nontyphoidal
Ciprofloxacin 750 mg PO once daily x 7-10 days
74
Treatment: Antimicrobial therapy
First choice antibiotic in ADULTS
Vibrio cholerae 01
Doxycycline 300 mg PO x 1 day
75
Treatment: Antimicrobial therapy
First choice antibiotic in CHILDREN
ETEC
Azithromycin 10 mg/kg/day PO once daily for 3 days
76
Treatment: Antimicrobial therapy
First choice antibiotic in CHILDREN
Shigella spp.
Azithromycin 10 mg/kg/day PO once daily x 3 days
77
Treatment: Antimicrobial therapy
First choice antibiotic in CHILDREN
Salmonella nontyphoidal
Azithromycin 20 mg/kg/day PO once daily x 7 days
78
Treatment: Antimicrobial therapy
First choice antibiotic in CHILDREN
Vibrio cholerae 01
Azithromycin 10 mg/kg/day PO once daily for 3 days
79
Antimotility agents (i.e. diphenoxylate/atropine; loperamide)
Offer symptomatic relief in watery diarrhea by reducing the number of stools
Slowing of fecal transit time may result in extended toxin-associated damage, worsening symptoms, and complications
Avoid antimotility agents in toxin-mediated dysenteric diarrhea (i.e. EHEC; shigellosis)
80
Treatment: Food Poisoning
| Clostridium botulinum
Respiratory support
Botulinum antitoxin
Equine globulins obtained from horses immunized with toxins A, B, and E
If evaluation occurs within hrs of ingestion:
Gastric lavage & induction of vomiting (to remove toxin)
Cathartics and enemas (to remove toxin)
81
Watery Diarrhea
| Norovirus: Sx
Nausea, vomiting diarrhea, abdominal cramps, myalgia
82
Watery Diarrhea
| Norovirus: Tx
Supportive care
83
Watery Diarrhea
| Rotavirus: Sx
Nausea, vomiting, diarrhea, fever, abdominal pain, lactose intolerance
84
Watery Diarrhea
| Rotavirus: Tx
Supportive care
85
Watery Diarrhea
| Vibrio cholerae: Sx
Profuse watery diarrhea, vomiting, and leg cramps; Death can work within hours without treatment
86
Watery Diarrhea
| Vibrio cholerae: Tx
Antibiotics + Supportive Care
| DOC: doxycycline Alternatives: tetracycline, erythromycin, azithromycin
87
Watery Diarrhea
Enterotoxigenic
E. coli (ETEC) : Sx
Watery diarrhea and abdominal cramping
| Responsible for ½ of all E. coli diarrheal illness; common cause of food/water outbreaks
88
Watery Diarrhea
Enterotoxigenic
E. coli (ETEC): Tx
Antibiotics + Supportive Care
DOC: ciprofloxacin
Alternatives: rifaxamin, azithromycin
89
Dysentery
Entero-hemorrhagic
E. coli (EHEC): Sx
Gastroenteritis, enterocolitis, sometimes bloody diarrhea and hemolytic-uremic syndrome
90
Dysentery
Entero-hemorrhagic
E. coli (EHEC): Tx
Supportive Care
| No ABX!!!!
91
Dysentery
| Salmonella nontyphoidal: Sx
Diarrhea (sometimes bloody), fever, and abdominal cramps
92
Dysentery
| Salmonella nontyphoidal: Tx
Antibiotics + Supportive Care
DOC: Ciprofloxacin and Levofloxacin
Alternatives: azithromycin
93
Dysentery
| Shigella spp.: Sx
Watery or blood diarrhea (8-10 stools/day), severe abdominal pain, fever, and malaise
94
Dysentery
| Shigella spp.: Tx
Antibiotics + Supportive Care
DOC: Ciprofloxacin and Levofloxacin
Alternatives: azithromycin
95
Dysentery
| Clostridium botulinum: Sx
Double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness
96
Dysentery
| Clostridium botulinum: Tx
Respiratory support, botulinum anti-toxin
