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Microbiology First Aid USMLE Step 1 > Basic Bacteriology- FA > Flashcards

Basic Bacteriology- FA Flashcards

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1
Q

Giemsa Stain: “Certain Bugs Really Try my Patience”

A

Giemsa: Chlamydia, Borrelia, Rickettsiae, Trypanosomes, Plasmodium

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2
Q
  • O2 dependent

- Examples: Nagging Pests Must Breathe

A

Obligate Aerobes:

  • Nocardia
  • Pseudomonas aeruginosa (p. AERuginosa = aerobic)
  • Mycobacterium tuberculosis
  • Bacillus
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3
Q

Can’t Breathe Air

  • Lack catalase and/or superoxide dismutase
  • Foul Smelling
A

Obligate Anaerobes:

  • Clostridium
  • Bacteroides
  • Actinomyces
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4
Q

Intracellular bugs: Obligate intracellular & Facultative inracellular
“Stay inside (cells) when it is Really Cold”
“Some Nasty Bugs May Live FacultativeLY”

A 
Obligate intracellular
-Rickettsia
-Chlamydia (Can't make own ATP)
Facultative Intracellular
-Salmonella
-Neisseria
-Brucella
-Mycobacterium
-Listeria
-Francisella
-Legionella
-Yersinia pestis
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5
Q

Serve as an antiphagocytic virulence factor
“Capsules” + protein conjugate serve as an antigen in vaccines

Quellung = capsular “swellung”
“SHiNE SKiS”

-opsonized then cleared by spleen

A

Encapsulated Bacteria

  • Streptococcus pneumoniae
  • Haemophilus influenzae type B
  • Neisseria meningitidis
  • Escherichia coli
  • Salmonella
  • Klebsiella pneumonia
  • group B Strep
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6
Q

you need PLACESS for your CATs.

Catalase degrades H2O2 before it can be converted to microbicidal products by the enzyme myeloperoxidase

A

Catalase-positive organisms

  • pseudomonas
  • Listeria
  • Aspergillus
  • Cadida
  • E.coli
  • S. Aaureus
  • Serratia
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7
Q

Vaccines- (3 conjugated and 1 no conjugated proteins)

A

Pneumovax- polysaccharide vaccine with no conjugated protein) and Prevnar (conjugated vaccine)

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8
Q

“CHunk norris hates PUNKSS”

A

Urease-positive bugs

  • Cryptococcus
  • H. pylori
  • Proteus
  • Ureaplasma
  • Nocardia
  • Klebsiella
  • S. epidermidis
  • S. saprophyticus
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9
Q 
Pigment-producing bacteria
-"Israel has Yellow sand" = ?
"Gold" = ?
Blue-green pigment = ?
Red pigment = ?
A

-Actinomyces israelii- yellow “sulfer” granules
-S. aureus- yellow pigment
pseudomonas aeruginosa- blue-green pigment
Serratia marcescens- red pigment (“red maraschino”)

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10
Q

Which bacteria Promotes evasion of host immune response?

Name the 3 bacteria associated with this.

A

Bacterial Virulence factors

  • Protein A (binds Fe region of Ig), Expressed by S. aureus
  • IgA protease (Enzyme that cleaves IgA- secreted by S. pneumoniae, H. influenzae type B, Neisseria
  • M protein (helps prevent phagocytosis- expressed by group A streptococci (pyrogenes)
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11
Q

Bacterial Virulence factors

-(binds Fe region of Ig), Expressed by S. aureus

A

Protein A

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12
Q

Bacterial Virulence factors

-(Enzyme that cleaves IgA- secreted by S. pneumoniae, H. influenzae type B, Neisseria

A

IgA protease

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13
Q

Bacterial Virulence factors

-helps prevent phagocytosis- expressed by group A streptococci (pyrogenes)

A

M protein

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14
Q

“Some Killers Have Pretty Nice Capsules”

- help avoid immune response

A 
Capsules
-S. PNA
Klebsiella pna
-H. influenza
-P. Aeruginosa
-Nisseria G
Criptococceus Neofarmi (fungi)
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15
Q

Exotoxin or Endotoxin??
Outer cell membrane of most gram-negative bacteria
Lipopolysaccharide
Bacterial chromosome
Low toxicity
Fever, shock = clinical effects
induces TNF and IL-1
Poorly antigenic
no toxoids formed and no vaccine available
Stable at 100 degrees C for 1 hour
Meningococcemia; sepsis by gram-negative rods

A

Endotoxin

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16
Q

Exotoxin or Endotoxin??

Certain species of some gram-positive and grame neg bacteria
Polypeptide
plasmid or bacteriophage- location of genes
High toxicity
induces high titer antibodies called antitoxins
Toxoids used as vaccines
Destroyed rapidly at 60 degrees C (except 1)
Tetanus, botulism, diphtheria

A

Exotoxin

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17
Q

Inhibit Protein Synthesis

-Diphtheria toxin

A

Corynebacterium diphtheriae (Exotoxin)

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18
Q

Inhibit protein synthesis
-Exotoxin A inhibits EF-2 = no protein sythensis
= Host cell death

A

Pseudomonas aeruginosa (Exotoxin)

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19
Q

Inhibit protein synthesis

Shiga-like toxin (SLT)

A

Enterohemorrhagic E. Coli (EHEC) (exotoxin)

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20
Q

Increased fluid secretion
Manifestation: Watery Diarrhea-
- “Labile in the Air “ (increased cAMP)
- “Stable on the Ground” (increased cGMP)

A

Enterotoxigenic E. coli (ETEC)
Heat- liable toxin (increase cAMP)
Heat-stable toxin (increased cGMP)

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21
Q
  • likely responsible for characteristic edematous borders of black eschar in cutaneous anthrax
  • mimics the adenylate cyclase enzyme (increased cAMP)
A

Bacillus Anthracis

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22
Q
  • Cholera toxin
  • Overactives adenylate cyclase (increased cAMP) by permanently activiting Gs -> increased Cl- secretion in gut and H2o efflux
  • Voluminous “rice-water” diarrhea
A

Vibrio Cholerae

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23
Q

Name 1 bacteria that Inhibit phagocytic ability

A

Bordetella pertussis

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24
Q

-Pertussis toxin
-overactivates adenylate cyclase (increase cAMP) by disabling G1, impairing phagocytosis to permit survival of microbe
Manifestation: Whooping cough

A

Bordetella pertussis

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25
Q

Name 2 bacteria that Inhibit Release of Neurotransmitter

A

Clostridium tetani

Clostridium botulinum

26
Q

Which bacteria is associated with:

  • Lock jaw & muscle rigidity
  • toxin prevents release of inhibitory (GABA and glycine) neurotransmitters in spinal cord
A

Clostridium Tetani

- tetanospasmin (toxin)

27
Q

Which bacteria is associated with:

  • Flaccid paralysis, floppy baby;
  • toxin prevents release of stimulatory (ACh) signals at neuromuscular junction -> flaccid paralysis
A

Clostridium Botulinum

-botulinum toxin

28
Q

Which 3 bacteria’s increase fluid secretion?

A

Enterotoxigenic E. Coli (EHEC)
Bacillus anthracis
Vibrio cholerae

29
Q

What vaccine is used for clostridium tetani?

A

tatanus toxoid

30
Q

Name the 2 lyse cell membranes bacteria.

A

Clostridium perfringens

Streptococcus pyogenes

31
Q
  • Alpha toxin
  • phospholipase that degrades tissue and cell membranes
  • Manifestation: Degradation of phospholipid C ->myonecrosis (“gas gangrene”) and hemolysis (“double zone” of hemolysis on blood agar)
A

Clostridium perfringens

32
Q

Toxin: Streptolysin O
Mechanism: Protein degrades cell membrane

A

Streptococcus pyogenes

33
Q

What are the 2 bacteria that cause Superantigens causing shock?

A

Staphylococcus aureus

Streptococcus pyogenes

34
Q

What are symptoms of Toxic shock syndrome?

A

Fever, rash, and shock

other toxins- scalded skin syndrome with exfoliative toxin and food poisoning with enterotoxin

35
Q

What is the toxin associated with Staphylococcus aureus?

A

Toxic shock syndrome toxin (TSST-1)

36
Q

What is the toxin associated with Streptococcus pyogenes?

A

Exotoxin A

37
Q

A lipopolysaccharide found in outer membrane of gram-negative bacteria

A

Endotoxin

38
Q

ENDOTOXIN

A 
E-dema
N-itric acid
D-IC/Death
O-uter membrane
T-NF-alpha
O-antigen
eXtremely heat stable
IL-1
N-eutrophil chemotaxis
39
Q

What are the components of the bacterial growth curve from L to R?

A

Lag phase
Exponential growth phase
Stationary phase
Death phase

40
Q

Describe the lag phase of the bacterial growth curve.

A

Metabolic activity without division

41
Q

Describe the exponential/log phase of the bacterial growth curve

A

Rapid cell division. Penicillins and cephaloporins act here as peptidoglycan is being made.

42
Q

Describe the stationary phase of the bacterial growth curve

A

nutrient depletion slows growth. Spore formation in some bacteria

43
Q

Describe the death phase of the bacterial growth curve

A

Prolonged nutrient depletion and buildup of waste products lead to death

44
Q

With whooping cough do you hear the “whoops” on inspiration or expiration?

A

With whooping cough: child coughs on expiration and “whoops on inspiration (toxin may not actually be a cause of cough; can cause “100 day cough” in adults.
- manifestation of bordetella pertussis

45
Q

Media used for isolation: Chocolate agar with factors V (NAD+) and X (hematin)

A

H. Influenzae

46
Q

Media used for isolation: Thayer-Martin (or VPN) media- Vancyomycin (inhibits gram-positive organisms), polymyxin (inhibits gram-negative organisms except Neisseria), and Nystatin (inhibits fungi); “to connect to Neisseria, please use your VPN client”

A

N. Gonorrhoeae & N. Meningitidis

47
Q

“to connect to Neisseria, please use your VPN client” ….What is VPN and what do each inhibit?

A
  • Vancyomycin (inhibits gram-positive organisms),
  • polymyxin (inhibits gram-negative organisms except Neisseria), and
  • Nystatin (inhibits fungi);
48
Q

Media used for isolation: Bordet-Gengou (potato) agar

A

B. pertussis

(Bordet for BORDETella

49
Q

Media used for isolation: Tellurite plate, loffler’s media

A

C. diphtheriae

50
Q

Media used for isolation: Eaton’s agar

A

M. pneumoniae

51
Q

Pink colonies on MacConkey’s agar (fermentation productes acid, turning colony pink); E. coli is also grown on eosin-methylene blue (EMB) agar as colonies with green metallic sheen

A

Lactose-fermenting enterics

52
Q

Media used for isolation: Charcoal yeast extract agar buggered with cysteine and iron

A

Legionella

53
Q

SABouraoud’s agar.

-(“Sab’s a FUN Guy!”)

A

Fungi

54
Q

Name 5 stains for bacteria.

A 
Giemsa
PAS (periodic acid- schiff
Aiehl- Neelsen (carbol fuchsin)
India ink
Silver stain
55
Q

What is the Giemsa stain used for?

“Certain Bugs Really Try my Patience”

A

Chlamydia, borrelia, rickettsiae, trypanosomes, plasmodium

56
Q

What is the PAS stain used for and what is it used to diagnose?
(PASs the Sugar)

A

Stains Glycogen, mucopolysaccharides- used to diagnose Whipple’s disease

57
Q

What is the Ziehl-Neelsen used for ?

My Nook is Fast

A

Acid-fast organisms (Nocardia, mycobacterium)

58
Q

What is the india ink used for?

A

Cryptococcus neoformans (mucicarmine can also be used to stain thick polysaccharide capsule Red)

59
Q

What is the silver stain used for ?

A

Fungi (e.g. pneumocystis), legionella, helicobacter pylori

“The Fun Helicopeter Silver Lining”

60
Q

What are the Gram stain limitations and why do they NOT stain well?
(hint: “These Rascals May Microscopically Lack Color”)

A

These bugs do NOT gram stain well:
Treponema (too thin to be visualized)
Rickettsia (intracellular parasite)
Mycobacteria (high lipid content in cell wall detected by carbolfuchsin in acid-fast statin)
Mycoplasm (no cell wall)
Legionella pneumophila (primarily intracellular)- use silver stain
Chlamydia (intracellular parasite; lacks muramic acid in cell wall

Microbiology First Aid USMLE Step 1 (10 decks)

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