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Year 5 - Pathology lectures > Microbiology > Flashcards

Microbiology Flashcards

1
Q

Microbiology 2 - Gastrointestinal infections

(Epidemiology)

Is the incidence over or underported? Why?

Who are most at risk from GI infections?

A

Epidemiology:

  • Undereported, since most infections are self limiting and last less than 24 hours, there is a huge underreporting of GI infections. Whereas in developing countries it tends to be higher due to poor sanitation.
  • Those who are most at risk are children (more exposure and less developed immune systems) and the elderly
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2
Q

Microbiology 2 - Gastrointestinal infections

What are the reportable infections?

A

Reportable infections:

  • Campylobacter
  • Salmonella
  • Shigella
  • E.Coli 0157
  • Listeria
  • Norovirus
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3
Q

Microbiology 2 - Gastrointestinal infections

What are the symptoms and causative organisms of Secretory Diarrhea, Inflammatory Disease and Enteric fever

A
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4
Q

Microbiology 2 - Gastrointestinal infections

Outline the incubation, duration of illness, mode of infection for common organisms that cause gastrointestinal infections

A
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5
Q

Microbiology 2 - Gastrointestinal infections

Name 2 organisms/mechanisms that causes secretory diarrhoea and how it has its effect

A

Secretory diarrhoea :

  • Toxins on the outside of the cell can cause and massive efflux of water out of the cell. For example in Cholera, cAMP will open Cl channels at the apical membrane of enterocytes. This will cause an efflux of Cl into the lumen and a loss of water and electrolytes.
  • Bacterial superantigens are also able to stimulate the antigen presenting cells, causing them to release large amounts of cytokines
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6
Q

Microbiology 2 - Gastrointestinal infections

  1. How much of the population are chronic carriers and transient of Staph. Aureus?
  2. What are the properties Staph. Aureus?
  3. What colour colonies does it form on blood agar?
  4. What toxin does it produce? What Interlukins does it stimulate?
  5. How do you treat a Staph.Aureus gastronintestinal infection?
A

Staph. Aureus: Food poisoning

  1. ⅓ of the population are chronic carriers and ⅓ are transient, it is spread by skin lesions on the food handlers.
  2. It is catalase, coagulase positive, gram positive coccus that will appear in tetrads, clusters on Gram stains.
  3. It forms yellow colonies on blood agar.
  4. Produces enterotoxin, that can can act as a superantigen, this stimulates the release of IL 1 and IL 2 that will cause prominent vomiting and watery non bloody diarrhoea,
  5. You do not treat since it is self limiting.
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7
Q

Microbiology 2 - Gastrointestinal infections

  1. What is a common food source of Bacillus cerus infections?
  2. What are Bacillus cerus’s properties?
  3. What syptoms does it cause? and what is the treament?
  4. What more severe issues can it cause?
A

Bacillus cereus:

  1. Food poisoning from rice
  2. These are gram positive rod spores, they are heat stable emetic toxin producing (that’s why reheating rice doesn’t kill them). Heat labile diarrhoeal toxin, when food is not cooked at a high enough temperature this can happen.
  3. Watery non bloody diarrhoea which is self limited,
  4. It is a rare cause of bacteraemia in vulnerable population and can cause cerebral abscesses.
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8
Q

Microbiology 2 - Gastrointestinal infections

What are the Clostridia Gram positive anaerobes?

A
  1. Clostridium botulinum
  2. Clostridium perfringens
  3. Clostridium difficile
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9
Q

Microbiology 2 - Gastrointestinal infections

  1. What are the main sources of Clostridium botulinum?
  2. How does it have it’s effect on the body?
  3. How is it treated?
A

Clostridium botulinum:

  1. These come from canned or vacuum packed food (honey/infants).
  2. Caused by consuming preformed toxin. It blocks Acth release from peripheral nerve synapses
  3. Treated with antitoxin.
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10
Q

Microbiology 2 - Gastrointestinal infections

​

  1. What is the source of Clostridium perfringens?
  2. How does it attatck the body?
  3. What is the incubation period?
  4. What are the symptoms?
A

Clostridium perfringens:

  1. Food poisoning from reheated food
  2. It attacks the normal flora of the small bowel, where the enterotoxin acts (superantigen). Tends to work on the colon and not the small bowel.
  3. The incubation period is 8 to 16 hours.
  4. Causes watery diarrhoea, cramps, little vomiting lasting 24 hours.
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11
Q

Microbiology 2 - Gastrointestinal infections

  1. What disease does Clostridium difficile cause?
  2. What is a common source of Clostridium difficile?
  3. Do you test children for it?
  4. What percentage of the community and hospitalised pateints have this?
  5. What do you do with patients on the ward with this and why? wh
  6. What is the treatment?
A

Clostridium difficile:

  1. Pseudomembranous colitis: One of the targets given by the Department of Health.
  2. Often a hospital acquired infection
  3. Don’t test children since a lot of them carry it in their gut, as well as a lot of people over the age of 65.
  4. About 3% of the community and 30% of hospitalised patients have this, it is antibiotic related (any, but used to be called the 4 C’s: cephalosporins, cipro and clindamycin).
  5. It’s an issue is infection control, you isolate patients with this since they can spread via their spores
  6. Treatment is with PO Metronidazole, vancomycin and stop antibiotics when possible.
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12
Q

Microbiology 2 - Gastrointestinal infections

  1. Which pateint group are particularly vulnerarble to listeria monocytogenes?
  2. What are listeria monocytogenes’d features?
  3. What is the typical infection souce?/What temp does it grow best at?
  4. What are the syptoms?
  5. What is the treatment?
A

Listeria monocytogenes:

  1. Pregnant women are particularly vulnerable.
  2. Beta haemolytic, aesculin positive with tumbling motility appearance under a microscope.
  3. Tend to get it from unpasteurised dairy, vegetables. Grows at 4 degrees C,
  4. GI watery diarrhoea, cramps, headache, fever little vomiting.
  5. Treatment with ampicillin
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13
Q

Microbiology 2 - Gastrointestinal infections

  1. What are the features of Enterobacteriaceae?
  2. Name a type of Enterobacteriaceae
  3. What type of diarrhoea does it cause?
  4. What is its source?
  5. How does E.Coli have its effect?
  6. What are the different types of E.Coli?
A

Enterobacteriaceae:

  1. Facultative anaerobes, glucose/lactose fermenters (LF), oxidase negative
  2. Escherichia coli
  3. Traveller’s diarrhoea
  4. Source: food/water contaminated with human faeces
  5. Enterotoxins:
    1. Heat labile stimulates adenyl cyclase and cAMP
    2. Heat stable stimulates guanylate cyclase
    3. Act on the jejunum, ileum not on the colon
  6. Different types include:
    1. ETEC: toxigenic main cause of traveller’s diarrhoea
    2. EPEC: pathogenic, infantile diarrhoea
    3. EIEC: insavice, dysentery
    4. EHEC: haemorrhagic, shiga like, verocytotoxin causes HUS
    5. Avoid antibiotics, thought to make it worse
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14
Q

Microbiology 2 - Gastrointestinal infections

  1. What are the properties of Salmonellae?
  2. What are the 3 species of Salmonellae?
  3. What Antigens are associated with it?
A

Salmonellae:

  1. Non lactose fermenters, H2S produces, TSI agar,

XLD agar, selenite F broth

  1. Three species: S.enteritidis, s,typhi, s.choleraesuis
  2. Antigens:
    1. Cell wall O (Groups A to I)
    2. Flagellar H
    3. Capsular Vi (Virulence, antiphagocytic)
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15
Q

Microbiology 2 - Gastrointestinal infections

What are the diseases caused by, transmission routes and symptoms of S.enterities and S.typhi?

A
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16
Q

Microbiology 2 - Gastrointestinal infections

  1. What are the properties of Shigella?
  2. What are its antigens?
  3. What are the Polysaccaride groups?
  4. What is its infective dose?
  5. Does it spread through animals? Does it have a carrier state?
  6. What disease does Shigella cause?/How does it affect the body?
  7. What antibiotics are needed?
A

Shigella:

  1. Community acquired, enteric pathogen. Non lactose fermenters, non H2S producers, non motile (salmonella does)
  2. Antigens:
    1. Cell wall O antigens
  3. Polysaccharide (groups A to D): s.sonnei, s.dysenteriae, s.flexneri (Men who have Sex with Men)
  4. The most effective bacterial enteric pathogens, very low infective dose of 50 pathogens
  5. No animal reservoir, spread by humans. No carrier state
  6. Dysentery
    1. Invading cells of mucosa of distal ileum and colon
    2. Producing enterotoxin (Shiga toxin)
  7. Avoid antibiotics (ciprofloxacin if required)
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17
Q

Microbiology 2 - Gastrointestinal infections

  1. What are the properties of the Vibros?
  2. What are the types of Vibros?
A
  1. Vibrios: Curved, comma shaped, late lactose fermeneters, oxidase positive
  2. Vibrio Cholerae, Vibrio parahaemolyticus, Vibrio vulnificus
18
Q

Microbiology 2 - Gastrointestinal infections

  1. What are the properites of Vibro Cholerae?
  2. What is its method of transmission?
  3. What are its symptoms?
  4. What is treatment?
A

Vibrio Cholerae:

  1. O1 group: epidemics, biotypes El. Non O1 group: sporadic or non pathogens
  2. Transmitted by contamination of water and food with human faeces
  3. Causes massive diarrhoea (rice water stool) without inflammatory cells
  4. Treat the water loss with dioralyte
19
Q

Microbiology 2 - Gastrointestinal infections

  1. What is the method of transmission of Vibrio parahaemolyticus?
  2. Where is Vibrio parahaemolyticus a major cause of diarrhoea
  3. Is Vibrio parahaemolyticus self limiting?
  4. How do you identify Vibrio parahaemolyticu?
A

Vibrio parahaemolyticus:

  1. Ingestion of raw or undercooked seafood, oysters for examples
  2. Major cause of diarrhoea in Japan
  3. Yes, self limiting for 3 days
  4. Identification: grows in salty 8.5% NaCl (like the fish it’s from)
20
Q

Microbiology 2 - Gastrointestinal infections

  1. What is the transmission route in Vibrio vulnificus?
  2. Who are particularly vulnerable?
  3. What is the treatment for Vibrio vulnificus and Vibrio parahaemolyticus?
A

Vibrio vulnificus:

  1. Cellulitis in shellfish handlers
  2. Fatal septicaemia with D+V in HIV patients
  3. Treat with doxycyline
21
Q

Microbiology 2 - Gastrointestinal infections

  1. What are the properties of Campylobacter?
  2. What are the common sources of Campylobacter?
  3. What is the most common type of Campylobacter? What are its features?
  4. Is it self limiting?
  5. What is the treament?
  6. What symptoms does it have?
  7. What can it lead to?
A

Campylobacter:

  1. Curved, comma shaped. Doesn’t need much oxygen, so is microaerophilic
  2. Often get it from poultry, can get it from unpasteurised milk, water with animal faeces
  3. C.jejuni at 42 degrees C. Oxidase positive, motile
  4. Yes. Self limiting but symptoms can last up to 20 days
  5. Only treat if immunocompromised (macrolide such as erythromycin)
    1. Treat with erythromycin or cipro if in the first 4 to 5 days
  6. Causes watery, foul smelling diarrhoea, bloody stools, fever and severe abdominal pain
  7. Can lead to guillain barre syndrome, reactive arthritis, Reiter’s…
22
Q

Microbiology 2 - Gastrointestinal infections

  1. What are the properties of Yersinia enterocolitica?
  2. What is its transmission route?
  3. Where are patients typically from?
A

Yersinia enterocolitica:

  1. Non lactose fermenter, prefers 4 degrees C
  2. Transmitted via food
  3. Typically from sub saharan Africa
23
Q

Microbiology 2 - Gastrointestinal infections

What are the 3 main types of protazoa?

A

Protozoa:

  1. Entamoeba histolytica
  2. Giardia lamblia
  3. Cryptosporidium parvum:
24
Q

Microbiology 2 - Gastrointestinal infections

  1. What is the transmission route of Entamoeba histolytica
  2. How is Entamoeba histolytica diagnosed?
  3. What is the treament of Entamoeba histolytica?
A

Entamoeba histolytica:

  1. Ingest cysts>> colonize in cecum > tenesmus
  2. Diagnosis by serology
  3. Treat with metronidazole and paromomycin in luminal disease
25
Q

Microbiology 2 - Gastrointestinal infections

  1. What are thje featutes of Giardia lamblia?
  2. What is the method of infection transmission?
  3. What effect does it have in the body
    What group are at high risk?
  4. How is the dianosis made?
  5. What is treamtent for Giardia lamblia?
A

Giardia lamblia:

  1. Distinctive pear shape. 2 nuclei, 4 flagella and a suction disk (this is how it gets into your system)
  2. Ingestion of cyst from faecally contaminated water and food
  3. Causes malabsorption of proteins
  4. Travellers, hikers at risk
  5. Diagnosis: stool microscopy, can do a “string test”
  6. Treat with metronidazole
26
Q

Microbiology 2 - Gastrointestinal infections

  1. ​Where does Cryptosporidium parvum infect?
  2. What symptoms does it cuase?
  3. What is seen in stools?
  4. What is treamtent for Cryptosporidium parvum?
A

Cryptosporidium parvum:

  1. Infects the jejunum
  2. Severe diarrhoea
  3. Oocysts seen in stool by modified Kinyoun acid fast stain
  4. Treatment with reconstitution of immune system
27
Q

Microbiology 2 - Gastrointestinal infections

  1. What is the infective dose for Norovirus?
  2. Is it environmentally resiliant?
  3. is there long term immunity?
  4. What is the most common strian?
A

Norovirus:

  1. Low ID (18 to 1000 viral particles)
  2. Environmental resilience (0 to 60 degrees C)
  3. No long term immunity
  4. G 2.4 is the most common strain currently
28
Q

Microbiology 2 - Gastrointestinal infections

  1. What are the properties of Rotavirus?
  2. Where does it infect?
  3. What syptoms does it cause?
  4. Do lots of people have antibodies to it?
  5. How many infections are needed for immunity?
  6. What is the economic burden?
A

Rotavirus:

  1. dsRNA “wheel like”.
  2. Replicates in mucosa of small intestine
  3. Secretory diarrhoea, no inflammation
  4. By age 6 most children worldwide have antibodies to at least one type
  5. Exposure to natural infection twice confers lifelong immunity
  6. Huge economic burden worldwide
29
Q

Microbiology 2 - Gastrointestinal infections

  1. What types of adenovirus cause a severe symptom?
  2. What is the diagnosis method?
A

Adenovirus:

Types 40 and 41 cause non bloody diarrhoea

Diagnosis by stool EM

30
Q

Microbiology 2 - Gastrointestinal infections

What are 3 faeco oral virus, beginning with P, E and H?

A

Other faeco oral viruses:

Poliovirus

Enterovirus (coxsackie)

Hepatitis A

31
Q

Microbiology 2 - Gastrointestinal infections

Name 6 methods of infections prevention and control

A

Prevention and Control:

  1. Breastfeeding, improved weaning process
  2. Clean water
  3. Sanitation
  4. Food handling
  5. Good handwashing
  6. Vaccines
32
Q

Microbiology 2 - Gastrointestinal infections

What vaccines can be offered for GI infective diseases?

A

Vaccines:

  1. Cholera
  2. Campylobacter
  3. ETEC
  4. Salmonella typhi
  5. Rotavirus, rotarix, live attenuated vaccines given by 2 PO doses
  6. Age is any child from 6 to 12 weeks
33
Q

Microbiology 2: GI Infections

What are the organisms, subspecies, clinical symtoms and treatment of Anaerobic GI infective organisms?

A
34
Q

Microbiology 2: GI Infections

What are the organisms, subspecies, clinical symtoms and treatment of aerobic GI infective organisms?

A
35
Q

Microbiology 2: GI Infections

What are the organisms, subspecies, clinical symtoms and treatment of Lactose fermenting GI infective organisms?

A
36
Q

Microbiology 2: GI Infections

What are the organisms, subspecies, clinical symtoms and treatment of Non Lactose fermenting GI infective organisms?

A
37
Q

Microbiology 2: GI Infections

What are the organisms, subspecies, clinical symtoms and treatment of “Misc” GI infective organisms?

A
38
Q

Microbiology 2: GI Infections

What are the organisms, subspecies, clinical symtoms and treatment of Listeria?

A
39
Q

Microbiology 2: GI Infections

What are the organisms, subspecies, clinical symtoms and treatment of Protazoa?

A
40
Q

Microbiology 2: GI Infections

What are the organisms, subspecies, clinical symtoms and treatment of Viruses?

A
41
Q

Microbiology 2: GI Infections

What are the symtoms and causative organisms of Secretory dairrhoea, Inflammatory diarrhoea and Enteric fever

A

Year 5 - Pathology lectures (7 decks)

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