Gastrointestinal infections Flashcards
1
Q
What is the most common outcome of GI infections?
A
Diarrhea (most common cause of death in developing countries)
2
Q
What is the common route of transmission of the GI infections?
A
1) Feaco-oral route (eating or drinking)
2) Self inoculation
3) Person to person
3
Q
What is meant by gastroenteritis?
A
They are syndromes of diarrhea and vomiting
4
Q
What is meant by diarrhea?
A
Frequent watery bowel and movements, commonly 3 or more loose stools in 24-hours
- If less than 14 days it is acute, if more then persistent
5
Q
What is meant by dysentery?
A
It is the passage of stool with blood and mucous
6
Q
What is meant by tenesmus?
A
The sensation of needing to pass stool even when the bowel is empty
7
Q
What is meant by enterocolitis?
A
Inflammation of the mucosa of the small and large intestine
8
Q
What are the different causes of gastrointestinal infections?
A
1) Bacteria
2) Viruses
3) Parasites
9
Q
What are the different bacteria that causes GI infections?
A
- Gram-negative
1) Enterobacteriaceae
1a) E.coli (common)
2a) Salmonella (common)
3a) Shigella (common)
4) Vibrio (common)
5) Campylobacter jejuni (common)
- Gram-positive
6) S.aureus
7) Bacillus cerus
8) C.perfringens (common)
9) C.botulinum (common)
10) C.difficle (common)
10
Q
What is the most common virus that causes GI infection?
A
Rotavirus
11
Q
What is the most common cause of GI infection in developed countries?
A
Escherichia coli, also for 1.UTI, 2.Traveler’s diarrhea
- Exogenous source
12
Q
What is the most common cause of bacterial GI infection in develop”ing” countries?
A
Campylobacters
13
Q
What is the cafeteria bug that causes GI infection?
A
Clostridium
14
Q
What is the bacteria that causes GI infections in hospital environment?
A
Clostridium difficle
15
Q
What is the most common virbrio bacterium?
A
Vibrio cholera
16
Q
What are the 4f’s that can cause gastroenteritis?
A
- Food
- Fluid
- Fingers
- Fly
17
Q
What are the clinical manifestation of GI tract infections?
A
1) Gastroenteritis
- Non-inflammatory gastroenteritis (Food poisoning)
- Inflammatory gastroenteritis
18
Q
What are the different types and causes of diarrhea?
A
1) Acute infectious diarrhea (gastroenteritis)
- <2-weeks
- Can results from: (emotional stress, food intolerance, organic substances, drugs, infectious agents)
1a) Inflammatory or blood diarrhea
2a) Non-inflammatory diarrhea (food poisoning)
2) Chronic diarrhea
- > 2-weeks
- Divided into six categories
1a) Osmotic
1b) Secretory
1c) Inflammatory
1d) Malabsorptive
1e) Chronic infections
1f) Motility disorders diarrhea
19
Q
What is the non-inflammatory gastroenteritis?
A
- Toxin-mediated
- Pathogens acts directly on the small intestine to induce fluid secretion
- Marked by the Prescence of watery diarrhea without pus cell and with no blood nor mucous in the stool, but with abdominal cramps, dehydration, nausea, and vomiting
- Primary treatment is to hydrate the patient
20
Q
What is meant by inflammatory gastroenteritis?
A
- Caused by an invasion or cytotoxin which inflames the gut wall
- It is marked by loose stool along with pus cells, mucous (can be with or without blood), tenesmus, abdominal cramping and fever
- Dehydration is unusual
21
Q
What is the cause of the non-inflammatory gastroenteritis?
A
It is caused by the production of various toxins by the bacteria (enterotoxins)
- Incubation period is several hours to few days
- Profuse watery diarrhea is the most common cause
22
Q
What are the different bacteria that could cause food poisoning via ingestion?
A
1) S.aureus
2) Bacillus cereus
3) Clostridium perfringens
4) Clostridium botulinum
23
Q
What is the bacteria that spreads it food poisoning toxin via (Meat, dairy, ice-cream, custard, coleslaw)?
A
S.aureus
24
Q
What are the foods that S.aureus spreads it food poisoning toxin by?
A
1) Meat
2) Dairy
3) Ice-cream
4) Custard
5) Coleslaw
25
What is the bacteria that spreads its food poisoning toxins via fried rice or meat?
- The emetic form of Bacillus cereus is found in the rice, and it causes vomiting (linked to heat-stable toxins)
- The diarrheal form of bacillus cereus is caused by heat-labile toxins which is typically found in meat
26
What is the bacteria that causes food poisoning via spreading its toxins through reheated food (buffets, cafeterias, meat, chicken, pork)?
Clostridium perfringins
27
What is the bacteria that can cause food poisoning via reheated food?
Clostridium perfringins
28
What is the bacteria that spreads its toxin and causes food poisoning via home-canned food, pickled goods, honey (for new born)?
Clostridium botulinum, (FYI it loves places where oxygen is low and that is why it is found in canned food)
29
What is vibrio?
- Gram-ve, flagellated curved rod/comma like shape
- It causes cholera
- The bacteria attaches to the intestinal epithelial cells producing the toxin cholera
- It has a high mortality rate in children in developed countries
- It is usually self-limiting
- Antibiotic are indicated for severe cases
30
How is vibrio transmitted?
1) Ingested of food or water (commonly shell fish)
2) Infection of a wound after swimming in a contaminated water
31
What are the direct effects of the cholera toxin?
- It is a AB Toxin, where A causes damage and B binds
- It activates the cAMP, which will cause reverse osmosis which will lead to watery diarrhea
32
Describe the diarrhea cause by vibrio cholera
1) Rapid onset
2) Diarrhea can be severe where 20L of water is lost per day
3) It is also called rice-water as there is a lot of mucous specks seen in the diarrhea
33
What is the bacteria that causes infection commonly through shell fish?
Vibrio cholera
34
What is the cafeteria bug?
Clostridium perfringens
35
What is the canned-food bug
Clostridium Botulinum
36
What are the different species of the bacteria vibrio?
1) Vibrio cholera
2) Vibrio parahaemolyticus
3) Vibrio vulnificus
37
describe vibrio cholera(briefly)
- Cholera toxin mediates the disease
- The infection can range from asymptomatic colonization or mild diarrhea to severe (rapidly fatal diarrhea)
- It spreads by the consumption of contaminated food or water
- The cholera toxins penetrates the intestinal wall and prevents the intestine from absorbing water from the digested food
38
Describe vibrio parahaemolyticus
- Can cause self-limiting diarrhea
- Associated with the consumption of contaminated raw shellfish
39
Describe vibrio vulnificus
- Very dangerous
- High mortality rate which is associated with primary septicemia and wound infections (particularly in patients with iron overload "like ppl with beta-thalassemia)
- Infections with this bacteria are associated with exposure of a wound to contaminated salt water or the ingestion of improperly prepared shell-fish
40
What is escherichia coli?
- Gram-ve rod
- The most common gram-ve rod in the GIT
- It is associated with gastroenteritis, UTIs, Meningitis, sepsis and extra-intestinal infections
- The leading cause of travelers diarrhea
- Its virulence factors include adherence, invasion and toxins
- Patients can be very old or very young
41
What is meant by traveler's diarrhea?
- It is a watery, self-limited diarrhea, vomiting, cramps, nausea, low-grade fever
- 1-3 days duration
- Treat with fluid replacement and antibiotic if needed
42
What is the mode of transmission of E.coli?
1) Person-to-person
2) Contaminated food and water (undercooked beef, unwashed fruit, etc)
43
Which specie of vibrio can cause septicemia?
Vibrio vulnificus
44
What is the bacteria that is the leading cause of traveler's diarrhea?
Escherichia coli
45
What are the different strains of E.coli?
1) Enterotoxigenic E.coli (ETEC)
2) Enterohemorrhagic E.coli (EHEC)
3) Enteropathogenic E.coli (EPEC)
4) Enteroinvasive E.coli (EIEC)
46
What are the features of the enterotoxigenic E.coli?
- Watery diarrhea due to heat-liable and heat stable enterotoxins
- It does not infect the intestinal wall
- It is the most common type of traveller's diarrhea
- Their is no fever not bloody diarrhea
47
What are the features of enterohemorrhagic E.coli
1) Bloody diarrhea and severe illness from an infected meet
2) Produces shigs-like toxin
3) It can lead to hemolytic uremic syndrome (a triad of hemolytic anemia, thrombocytopenia and acute kidney injury)
4) The only treatment is supportive
48
What are the features of enteropathogenic e.coli?
1) Watery diarrhea
- No toxins are produced
2) Adherence is its main virulence factor
3) It is a common infection in children
49
What are the features of enteroinvasive e.coli?
1) Bloody diarrhea and fever due to intestinal wall invasion (inflammatory diarrhea)
2) Closely related to shigella
50
Which strain of e.coli is the most common cause of travelers diarrhea?
Enterotoxigenic E.coli
51
What species of E.coli causes bloody diarrhea?
1) Enterohemorrhagic E.coli
2) Enteroinvasive E.coli
52
What are the species of Escherichia coli that causes watery diarrhea?
1) Enterotoxigenic E.coli
2) Enteropathogenic E.coli
53
Which strain of Escherichia coli causes hemolytic uremic syndrome?
Enterohemorrhagic E.coli
54
Who is most susceptible to viral non-inflammatory gastroenteritis?
- Infants and young children especially those in developing countries
- It causes morbidity and mortality
- It has a rapid onset with a incubation period of 4-48 hours
55
What is the most common virus that causes viral non-inflammatory gastroenteritis?
Rotavirus
56
Describe the rotavirus
1) Spreads via the faeco-oral route
2) It destroys the intestinal epithelium
3) It is characterized by severe diarrhea, abdominal pain and fever
4) It is a self-limited disease, however vaccination is recommended
57
Tenesmus is characteristic of which type of gastroenteritis?
Inflammatory gastroenteritis
58
Describe the inflammatory gastroenteritis
1) It affects both the small and large intestines
2) Stool volume is small, and it contains mucous and white blood cells (indicates inflammation)
3) Patients usually suffer from fever, abdominal cramps, and pain while trying to defecate
59
Describe the bacteria campylobacter
- Thin, curved, motile
- Gram -ve rod
- It s microaerophilic and grows best at 42 degrees
- Most common cause of enteritis, due to zoonotic infection or improperly prepared poultry (is loves hot meals that are placed in a sealed bag)
- Bloody diarrhea is the most common manifestation (especially in children)
- Self limited, but can stay for 1-2 weeks
- It is associated with guillain barre syndrome
60
Describe the clostridium difficile bacteria
- Gram +ve rods
- It can cause pseudomembranous colitis and or diarrhea
- It is commonly due to prolonged usage of antibiotics
- Clinically it can cause (antibiotic-associated diarrhea, and pseudomembranous colitis)
61
What is meant by antibiotic associated diarrhea?
- Causes an acute diarrhea that generally develops in 5-10 days after the initiation of an antibiotic treatment
- It can be self-limited or more protracted
- Clindamycin, penicillin, cephalosporins, fluoroquinolones are main ones
62
What is pseudomembranous colitis?
- A more severe form of C.difficle disease with profuse diarrhea, abdominal cramping and fever
- White plaques are seen over the intact colonic tissue
63
What is shigella?
1) Gram -ve, non-motile rods
2) It is not flagellated nor invasive
3) It is common in children of 1-4 years
4) It is transmitted by the four F's (Finger, feces, flies, food), it was spread among soldiers in the trenches of the wars(Person to person)
5) The most common disease it causes is shigellosis (gastroenteritis)
64
What is shigellosis?
watery diarrhea which progresses within 1-2 days to bloody diarrhea (as the bacteria invades the intestinal mucosa leading to inflammation and necrosis "but unlike salmonella it does not go beyond the GI "salmonela motile, shegala is not""), abdominal cramps, fever and tenesmus
- A severe form of shigellosis is caused by Shigella dysenteriae due to the shiga toxin (desentery means bloody, mucus-containing, small volume stool, with pain while defecating)
- The duration of the disease is 1-2 weeks
- Usually self-limiting
65
Describe salmonella
- Gram -ve rods with flagella
- It is motile and invasive
- It is a common cause of food-associated diarrhea in many developing countries
- Incubation period is 1-3 days
- It is associated with enteritis, enteric fever, bacteremia (blood culture is imp)
66
How is salmonella transmitted?
- Faeco-oral spread
1) Contaminated food (poultry, eggs, and dairy products)
2) Transmitted by turtle pet
67
What are the different salmonella species?
1) Face-oral spread (non-typhoid salmonella)
2a) Salmonella typhi
2b) Salmonella pratyphi
- Both are strictly human pathogens
- They can cause a localized infection (like gastroenteritis) or a systemic infection (like typhoid and paratyphoid fever)
- Typhoid has a characteristic "rose spots" in the abdomen
- Antibiotics is required in the severely ill individuals (when they come with fever) other than that it is self-limiting
68
What is the management of GI infections?
- According to the etiology
1) Rehydration is the most important thing (Oral rehydration solution)
2) Most GI bacteria require no antibiotic
- Most viral diarrhea are self-limiting
3) Parasitic diarrhea must be treated with an anti-parasitic/anti-helminth agent
- Antibiotics are only indicated for severe disease with potential complications like salmonella
- For prevention (improve sanitation, clean drinking water, hand-wash)
