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Phase 2a Gold Standard > ICS - Microbiology (microscopy - do first!) > Flashcards

ICS - Microbiology (microscopy - do first!) Flashcards

1
Q

This powerpoint was used as reference. Use as guide if visual reference needed. Mark 5 when read.

A

https://drive.google.com/file/d/1k6UY2u7nKcj8ot-XU3WikSA2bcIQlNLx/view?ts=627aa1cc

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2
Q

Gram positive cocci, what test should be done?

A

Catalase test
- Positive = staphylococcus (purple clusters)
- Negative = streptococcus (purple pairs/chains)

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3
Q

If a catalase test comes back positive, what does this show, and what test should be done next?

A

Staphylococcus

Coagulase done next
- Positive = Staphylococcus aureus
- Negative = S. epidermidis or saprophiticus

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4
Q

Gram positive cocci, catalase positive, coagulase positive, what bacteria is it?

A

Staphylococcus aureus

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5
Q

Gram positive cocci , catalase positive, coagulase negative, what bacteria is it?

A

S. epidermidis
S. saprophiticus

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6
Q

Gram positive cocci are catalase negative. What does this show? What test should be done next

A

Streptococcus

Haemolysis using blood agar. Results can show:
- alpha (partially) haemolytic
- beta (fully) haemolytic
- Non haemolytic

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7
Q

Gram positive cocci, catalase negative what is the genus of the bacteria?

A

Streptococcus

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8
Q

Gram positive cocci, catalase negative, a-haemolytic. What bacteria can it be and how does it show on agar

A

S. pneumoniae
Viridians streptococcus
(S. oralis
S. sanguinis)

Dark green on agar plate

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9
Q

What can be done to further differentiate alpha haemolytic streptococci? What are the results of this?

A

Optochin sensitivity test.
Sensitive (zone of inhibition) - S. pneumoniae
Resistant - Viridians strep

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10
Q

Gram positive cocci, catalase negative, b-haemolytic. What bacteria is it and how does it show on agar

A

Complete haemolysis

S. pyogenes (Group A strep)
S. agalactiae (Group B strep)

Pale yellow and transparent

(S=Strep)

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11
Q

What test can be done to further classify beta haemolytic bacteria?

A

Lancefield agglutination test

Uses antibodies to determine bacteria using their surface antigens.

Group A - S pyogenes
Group B - S agalactiae

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12
Q

Gram positive cocci, catalase negative, non haemolytic. What bacteria is it and how does it show on agar

A

S. mutans
S. millieri
Enterococcus faecalis

No haemolysis, agar unchanged.

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13
Q

What are the gram positive, aerobic bacilli

A

Cornybacterium (e.g. C.diphtheriae)
Listeria
Bacillus

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14
Q

What is the gram positive, anaerobic bacillus species

A

Clostridium
(e.g. C. difficile, C. tetani)

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15
Q

How are mycobacterium stained

A

Ziehl-Neelsen stain, as their high lipid content means they are acid fast, so can’t be gram stained.

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16
Q

How does M. tuberculosis stain?

A

Stains red with a Ziehl-Neelsen stain

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17
Q

The majority of gram negatives are bacilli. What notable species are gram negative cocci?

A

Neisseria (e.g. N meningitidis)
Moraxella

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18
Q

What is the notable anaerobic, gram negative bacilli? (the rest are aerobic)

A

Bacteroides
e.g. B. fragilis (commonly found in colon)

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19
Q

How are gram negative bacilli with simple growth requirements cultured?

A

Lactose fermenting on MacConkey agar

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20
Q

How do lactose fermenters appear on MacConkey agar?

A

Red/PINK

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21
Q

How do non lactose fermenters appear on MacConkey agar?

A

Pale/ no colour change

22
Q

Gram negative bacilli, appear pink on MacConkey agar, what is it?

A

Lactose fermenters

Escherichia (E.coli)
Klebsiella

23
Q

A gram negative bacillus grows a pale culture on MacConkey agar. What does this show?

A

Non lactose fermenters

  • Salmonella
  • Shigella
  • Pseudomonas
24
Q

How can non lactose fermenters (MacConkey pale) be further differentiated?

A

Oxidase test

Positive = Pseudomonas aeruginosa
Negative = Salmonella, shigella

25
Q

How can salmonella and shigella be differentiated between?

A

Culture on XLD agar.
Salmonella - red with black centres
Shigella - Just red

All others turn it yellow

26
Q

What agar is used to detect bacteria with fastidious growth requirements

A

Chocolate agar

27
Q

What bacteria have fastidious growth requirements, so must be cultured on chocolate agar?

A

Helicobacter
H. Influenza
Legionella. pneumophilia
Bordatella pertussis

28
Q

How is Campylobacter jejuni cultured

A

On CCDA charcoal plate

29
Q

How is H influenzae cultured and how is it treated

A

Factors X and V added to chocolate agar

Treated with amoxicillin and doxycycline

30
Q

Viridians streptococci properties, examples, infection

A

A-haemolytic and optochin resistant.
S. sanguinis, S. oralis
Found in mouth, cause deep organ abscesses (IE, brain, liver)

31
Q

What are group A Strep and what do they cause

A

A = S. pyogenes

Tonsilitis, pharyngitis, skin infections

32
Q

What are group B Strep and what do they cause

A

B = S. agalacticae

Neonatal sepsis and neonatal meningitis 15 mins in

33
Q

Give the properties of H pylori

A

Curved, motile bacilli with flagella.

34
Q

What classes of antibiotics inhibit cell wall synthesis

A
  • Beta lactams (penicillins, cephalosporins)
  • Glycopeptides (vancomycin)
35
Q

Give the types of penicillin, with the infections they are indicated in

A

Flucloxacillin - Staph aureus, strep pyogenes (group A)
Benzylpenicillin - Strep, pneumococcal pneumonia, meningitis
Amoxicillin - UTI, listeria, enterococci

36
Q

Give the types of cephalosporin

A

1st gen - Cephalexin
2nd gen - Cefuroxime
3rd gen - Ceftriaxone

37
Q

Side effects of vancomycin

A
  • nephrotoxicity

Avoid in pregnancy

38
Q

What syndrome can be caused by Cephalosporins

A

Stephens-Johnson syndrome (epidermal necrosis- itchy skin, sore throat, sore eyes, rash, blister) - can kill

39
Q

What Antibiotics inhibits nucleic acid synthesis

A

Folate synthesis:
Trimethoprim
Sulfonamides (co trimoxazole)
/
DNA Gyrase:
Fluoroquinolones (-foxacin)
/
RNA polymerase:
Rifampicin
/
Metronidazole

40
Q

Give the class of ciprofloxacin with their MoA

A

Fluoroquinolones (basically any -floxacin)

Inhibit DNA gyrase

41
Q

What antibiotics inhibit folate synthesis

A

Trimethoprim
Sulfonamides (Including co-trimoxazole)

(inhibit dihydrofolate reductase)

42
Q

What is the MoA of Rifampicin

A

Binds to RNA polymerase

43
Q

What is the MoA of metronidazole, and what is it indicated in?

A

Breaks the DNA Strand

Indicated in anaerobic parasites, and prophylaxis in GI surgery

44
Q

When is Rifampicin contraindicated

A

Jaundice

45
Q

When is metronidazole contraindicated

A

Interactions with alcohol - causes profuse vomiting

46
Q

What antibiotic classes inhibit protein synthesis

A
  • Tetracyclines (doxycycline)
  • Aminoglycosides (gentamicin)
  • Chloramphenicol
  • Macrolides (clarithromycin, azithromycin, erythromycin)
47
Q

What antibiotics inhibit 30s protein synthesis

A

Tetracyclines (doxycycline)
Aminoglycosides (streptomycin, gentamicin)

48
Q

What antibiotics inhibit 50s protein synthesis

A

Macrolides - Azithromycin

49
Q

What does doxycycline do

A

It is a broad spectrum antibiotic

50
Q

When is gentamycin contraindicated

A

Myasthenia gravis

Phase 2a Gold Standard (28 decks)

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