USMLE Microbiology > Basic Bacteriology > Flashcards

Basic Bacteriology Flashcards

(43 cards)

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1
Q

What bacteria do not gram stain well?

A

These Little Microbes May Unfortunately Lack Real Colour

  • Treponema, Lieptospira (too thin)
  • Mycobacteria (high lipid content)
  • Mycoplasma, Ureaplasma (no cell wall)
  • Legionella, Ricketsia, Chlamydia, Bartonella, Anaplasma Ehrlichia (intracellular, also Chlamydia have less muramic acid in peptidoglycan cell wall)
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2
Q

What bacteria can be visualised through a Giemsa stain?

A

Clumsy Rick Tripped on a Borrowed Helicopter Plastered in Gems

  • Chlamydia
  • Ricketsia
  • Trypanosomes
  • Borrelia
  • Helicobacter pylori
  • Plasmodium
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3
Q

What does Periodic-acid-Schiff visualise?

A 
Tropheryma Whipplei (Whipple's disease)
- Glycogen, mucopolysaccharides
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4
Q

What does Ziehl-Neelsen (carbol fuchsin) stain visualise?

A
  • Acid-fast bacteria
  • Mycobacteria, Nocardia (stains mycolic acid in cell wall)
  • Protozoa (Cryptosporidium oocyts)
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5
Q

What cna be used instead of Ziehl-Neelsen stain for screening?

A

Auramine-rhodamine stain

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6
Q

What stains are used to visualise Cryptococcus Neoformans?

A
  • India ink

- Mucicarmine can also be used tostain the polysaccharide capsule red

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7
Q

What can Silver stain visualise?

A
  • Fungi (coccidioides, pneumocytis jirovecii)
  • Legionella
  • Helicobacter pylori
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8
Q

What is an example of a fluorescent antibody stain which can visualise a certain bacteria (and/or virus)?

A

FTA/ABS for syphilis

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9
Q

What can lipoteichoic acid induce?

A
  • TNF-alpha

- IL-1

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10
Q

Give an example of a selective and indicator (differential) media?

A
  • Selective = Thayer-Martin agar for Neisseria

- Indicator = MacConkey for E.coli (turns pink)

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11
Q

What agar is used to grow H influenzae?

A

Chocolate agar

  • Contains factor V (NAD+) and
  • Factor X (hematin)
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12
Q

What does Thayer-Martin agar contain?

A
  • Vancomycin
  • Colistin
  • Trimethoprim
  • Nystatin
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13
Q

What agar/mediums may grow Bordetella pertusis?

A
  • Bordet-Gengou agar (potato extract)

- Regan-Lowe medium (chorcoal, blood, antibiotic)

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14
Q

What may grow C diptheriae?

A
  • Tellurite agar

- Loffler medium

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15
Q

Mycoplasma pneumoniae is grown on what agar?

A

Eaton agar (requires cholesterol)

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16
Q

What is E coli grown on?

A

Eosin-methylene Blue (EMB)

- Colonies with green metallic sheen

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17
Q

How do lactose producing bugs create a pink colour on MacConkey agar?

A

Fermentation produces acid, causing colonies to turn pink

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18
Q

What bugs are grown on Charcoal yeast extract buffered with cysteine and iron?

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A
  • Brucella
  • Francisella
  • Legionella
  • Pasteurella
    The Ella siblings, Bruce, Francis, a legionairre and a pator (pasteurella) built the Sistine (cysteine) chapel out of charcoal and iron
19
Q

What agar can fungi be grown on?

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A

Subouraund agar

20
Q

After immunocompromise or TNF-alpha inhibitor use where can M tuberculosis appear?

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A

Apices of the lungs

21
Q

What are examples of anaerobes?

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A
  • Clostridium
  • Bacteroides
  • Fusobacterium
  • Actinomyces israelii
    Cant Breathe Fresh Air
22
Q

What do anaerobes generally lack?

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A

Catalase and/or superoxide dismutase

- Susceptible to oxidative damage

23
Q

What type of antibiotics are ineffective against anaerobes?

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A

Aminoglycosides as they require O2 to enter into the bacterial cell

24
Q

What are examples of some faculative anaerobes?

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A
  • Streptococci
  • Staphylococci
  • Enteric gram negatives
25
What are examples of obligate intracellular bacteria?
- Rickettsia - Chlamydia - Coxiella
26
What are examples of faculative intracellular bacteria?
- Salmonella - Neisseria - Brucella - Mycobacterium - Listeria - Francisella - Legionella - Yersinia pestis
27
What are examples of encapsulated bacteria?
- Pseudomonas aeruginosa - Streptococcus pneumoniae - Haemophilus influenzae type B - Neisseria meningitidis - Escherichia coli - Salmonella - Klebsiella pneumoniae - Group B Strep Please SHiNE my SKiS
28
What do asplenics require vaccinations against?
- N meningitidis - S pneumoniae - H influenzae
29
What do encapsulated organsims' vaccines have to promote T cell activation?
Vaccines containing polysaccharide capsule antigens are conjugated to a carrier protein, enhancing immunogenicity by promoting T cell activation and subsequent class switching.
30
What are the Urease-positive organisms?
Pee CHUNKSS - Proteus - Cryptococcus - H pylori - Ureaplasma - Nocardia - Klebsiella - S epidermidis - S saprophyticus
31
What is the action of urease?
Urease hydrolyzes urea to release ammonia and CO2, increases pH
32
What stones do urease-positive organisms create?
Struvite (magnesium ammonium phosphate) stones, particularly proteus
33
What does catalase do?
Degrades H2O2 (hydrogen peroxide) into H2O and bubbles of O2
34
People with what disease are susceptible to catalase positive organisms?
Chronic Granulomatous disease (NADPH oxidase deficiency)
35
What are examples of catalase positive organisms?
- Nocardia - Staphylococci - Serratia - Candida - Listeria - E coli - Burkholderia cepacia - Pseudomonas - Aspergillus - Helicobacter pylori - Bordetella pertusis
36
What are the pigment-producing bacteria?
- Actinomyces israelii = Yellow - S aureua = Gold - P aeruginosa = Green/blue - Serratia marcescens = red
37
What organism affects people with catheters and other prosthetic devices?
S epidermidis
38
What organism comes through dental plaques and may cause infective endocarditis?
- Viridans streptococci (S mutans, S sanguinis)
39
Pseudomonas aeruginosa may cause what?
- Ventilator-associated pneumonia - Pneumonia in patients with CF - Contact lens associated keratitis
40
What bacteria may cause Otitis media?
Nontypeable (unencapsulated) H influenzae
41
What spore forming bacteria cause gas gangrene?
C perfingens
42
What gram of bacteria cannot produce spores?
Gram negative
43
What are examples of spore-producing bacteria?
- B antracis (anthrax) - B cereus (food poisoning) - C botulinum (botulism) - C difficile (pseudomembranous colitis) - C perfingens (gas gangrene) - C tetani (tetanus)
USMLE Microbiology
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