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Gastrointestinal > Gastroenteritis > Flashcards

Gastroenteritis Flashcards

1
Q

Where does colonization and normal flora occur in the human body?

A 
Eyes (tears, lysozymes)
Skin (structural barrier, sweat, sebum, lactic acid, propionic acid)
Urinary tract (acidic urine, vaginal lactic acid, lysozyme)
GI tract (stomach acidity, peristalsis, normal flora)
Respiratory tract (cough and sneezing, mucus, ciliary action, phagocytes and lysozymes)
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2
Q

What are the micro-organisms present in oral cavity?

A

Viridans streptococcus
Candida
anaerobic gram positive
anaerobic gram negative

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3
Q

What are the micro-organisms present in the large bowel?

A

Enterobacteriaceae - E.coli, klebsiella spp. , enterobacter spp., proteus spp.,
Milleri grp. streptococcus
anaerobic gram positives - clostridium, candida
anaerobic gram negative - bacterioidess

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4
Q

Define virulence

A

The likelihood of causing a disease

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5
Q

Steps of pathogenic infection

A
  1. Exposure
  2. Adhesion
  3. Invasioin
  4. Colonisation
  5. Toxicity
  6. Tissue and organ damage
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6
Q

What is the common complication of E.coli 0157 infection?

A

HUS - Haemolytic Uraemic syndrome

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7
Q

What is the incubation period?

A

It is the colonization phase during which the pathogens replicate in their hosts

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8
Q

What is the prodromal period?

A

It is the phase during which the early symptoms and signs of the disease are presented

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9
Q 
What immune system component get activated in response to the following bugs?
Bacteria
Virus
Fungi
Protozoans
Worms
A

Bacteria - phagocytes, antibodies and B-lymphocytes, compliment
Virus - T - lymphocytes and B- lymphocytes
Fungi - phagocytes, T-lymphocytes and eosinophils
Protozoans - T-lymphocytes and eosinophils
Worms - Mast cells, eosinophils

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10
Q

What are the special features of gram negative bacteria?

A 
Thin peptigoglycan layer
outer LPS layer (lipopolysachharide)
Produces endotoxins
More resistant to antibiotics
Purple on gram stain
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11
Q

What are the features of gram positive bacteria?

A 
Thick peptidoglycan layer
No outer LPS layer
Produces exotoxins
More susceptible to antibiotics
Violet on gram stain
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12
Q

What is an enterobacteriaceae?

A

It is a gram negative rod bacteria

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13
Q

Examples of lactose fermenting enterobacteriaceae

A

E.coli, Klebsiella spp., Enterobacter spp.

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14
Q

Examples of non-lactose fermenting enterobacteriaceae

A

Shigella spp., salmonella spp., Yersinia spp.

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15
Q

What are the features of Enterobacteriaceae?

A 
Gram negative
straight rods
non-spore producing
mobile or non-mobile
facultative anaerobes
increasing resistance
ferment sugars 
oxidase negative
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16
Q

What is pseudomonas?

A

It is a gram negative, glucose non-fermenting, non-lactose fermenting, oxidase positive bacilli

17
Q

Which bugs in enterobacteriaceae are non-motile?

A

Shigella and klebsiella

18
Q

What are the microbiological tests for enterobacteriaceae?

A

1.Gram stain
2. Culture/ primary isolation media -
Blood agar 18-24 hrs
McConkey agar 18-24 hrs - lactose fermentors
turn it pink
3. Cystine-lactose-electrolyte deficient (CLED)
4. Chromogenic agar
5. biochemical tests - Oxidase, Indole, Lactose

19
Q

Molecular methods to detect enterobacteriaceae

A

MALDI-TOF (Mass SpectrometryMatrix-Assisted Laser Desorption/Ionisation - Time of Flight)
very quick
not that expensive
can discriminate btw highly genetically similar organisms
difficult to differentiate btw salmonella, species of ecoli and shigella

20
Q

What are the various serotyping methods used to identify enterobacteriaceae?

A

Based on the immuno-reactivity of various antigens.

i.e., cell wall (O) polysaccharides, flagella (H) proteins and other cell wall carbohydrates

21
Q

How does enterobacteriaceae cause infections?

A
  1. Motility - flagella allows movement( except in shigella and klebsiella)
  2. Adherence - fimbriae (shorter than flagella and helps to adhere to the tissues)
  3. endotoxins - from the LPS layer which cause fever
  4. enterotoxins - eg. shiga toxin
22
Q

What happen to the environmental growth characteristics as you go further down the GI tract?

A

It goes from an aerobic(upper GIT) to an anaerobic environment (lower GIT)
pH increases from 2 to 7

23
Q

What is the normal flora in the jejunum?

A

coliforms and anaerobes

24
Q

what is the normal flora in the colon(faecal flora)?

A

Large numbers of coliforms
Anaerobes
Enterococcus faecalis

25
Q

what are the common anaerobes present in the colon?

A

Clostridium spp. and bacteriodes spp.(gram negative)

26
Q

What do bacteria need to multiply?

A

Time
Temperature
Food source
Moisture

27
Q

What does having an antibiotic dose increase your risk to?

A

Infection to C.difficile

28
Q 
What do the following factors increase your risk to?
Foreign Travel
Day care exposure
Recent Antibiotics
Raw seafood 
Cruise ships
A

1.Foreign travel: diarrhea - Enterotoxigenic E.coli
South-east asia - Vibrio
S. America, Asia, Africa - Rotavirus
2. Day care exposure - Rotavirus
3. Recent antibiotics - C. difficile
4. Raw seafood - Non- cholera vibrio
5. Cruise ships - norovirus

29
Q

Features of bacillus cereus
sources
disease caused
management

A

Gram positive, rod shaped, aerobic/ facultative anaerobic beta haemolytic bacterium.
Source:- 1) FRIED RICE syndrome - Improperly refrigerated cooked rice or meat
incubation time - 1-6 hrs
Disease:- Upper GIT severe nausea and vomiting, diarrhea and
2) Meat, stew, gravy, vanilla sauce
incubation time - 10-16 hrs
Disease:- abdominal cramps, watery diarrhea and nause
Treatment:- supportive care, oral re-hydration and rest

30
Q

Features of E.coli 0157 and complications of E.coli 0157?

A

E.coli 0157 is a gram negative stain.
Produces Shiga-like toxin (STEC) - toxigenic
Complications - HUS ( Haemolytic Uraemic Syndrome)
Renal Failure

31
Q

What are the Sources and mode of transmission of E.coli 0157?

A

Sources and transmission - Faceal-oral route
Raw and unpasteurised milk
Under-cooked beef/ meat
Raw leafy vegetables, unpasteurized juices
touching infected animals
Drinking contaminated water
Touching infected people and not washing
hands properly

32
Q

What is the incubation period, presentations and its duration in E.coli 0157 infections?

A

Presentations - diarrhoea
blood in poo
vomiting
stomach cramps
fever
Incubation - 3-5 days
Duration - 5-10 days

33
Q

What is the management for E.coli 0157?

A

Management:- NO ANTIBIOTICS
NO NSAIDS
NO ANTI-MOTILITY DRUGS
Supportive treatment, Oral re-hydration
Hygiene

34
Q

Diagnosis investigations for E.coli .

A 
McConkey agar
Sorbitol McConkey agar
Antisera for serotypes
ELISA identifies toxins
DNA of toxin genes can be identified
Bloody stool but culture negative?
Sent for more specialist tests
Low numbers
Detection of verotxoin gene
Typing to trace source

Selective culture
Sorbitol non fermenter (SNF)
E coli isolated
Check for O157 antigen

35
Q 
what are the features
sources and mode of transmission 
disease and presentation + duration
incubation period
complications
treatment
management (next)
A

Gram positive anaerobe, spore- producing, spores which are acid resistant, produces toxin A and B

Risk + Mode of transmission - Indv. with a previous antibiotic therapy in the past 3-6 months
Risk - Old patients, PPI’s, any Ab course esp 4c’s
4 C’s - Co-amoxiclav, Cephalosporin, Ciprofloxacillin and Clindamycin
MoT- Faecal-oral route (unwashed hands of healthcare workers and others)

Presentation - Watery diarrhoea with streaks of blood
Fever
Abdominal pain and tenderness
Severe dehydration - dry mouth and tongue
High Resp rate
Low BP
High pulse rate

Complications - Toxic megacolon
Pseudomembranous colon
Perforation of the colon
Sepsis

Treatment :- Metronidazole ( PO 10 days tds)
severe- Vancomycin - (po 10 days)
+ IV metronizaol

36
Q

Management of those with C.diff infection

A

Hygiene and infection control

Keep patient in isolated, side rooms and use PPE
Wash hands and blood tray with SOAP AND WATER , NOT GEL
As spores can only be killed by soap and water
Wash contaminated clothes, sheets and towels daily
Wash hands frequently
Clean contaminated surfaces

Gastrointestinal (13 decks)

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