Basic Bacteriology- FA Flashcards Preview

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

Flashcards in Basic Bacteriology- FA Deck (60):
1

Giemsa Stain: "Certain Bugs Really Try my Patience"

Giemsa: Chlamydia, Borrelia, Rickettsiae, Trypanosomes, Plasmodium

2

-O2 dependent
-Examples: Nagging Pests Must Breathe

Obligate Aerobes:
-Nocardia
-Pseudomonas aeruginosa (p. AERuginosa = aerobic)
-Mycobacterium tuberculosis
-Bacillus

3

Can't Breathe Air
-Lack catalase and/or superoxide dismutase
- Foul Smelling

Obligate Anaerobes:
-Clostridium
-Bacteroides
-Actinomyces

4

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

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

5

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

Encapsulated Bacteria
-Streptococcus pneumoniae
-Haemophilus influenzae type B
-Neisseria meningitidis
-Escherichia coli
-Salmonella
-Klebsiella pneumonia
-group B Strep

6

you need PLACESS for your CATs.

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

Catalase-positive organisms
-pseudomonas
-Listeria
-Aspergillus
-Cadida
-E.coli
-S. Aaureus
-Serratia

7

Vaccines- (3 conjugated and 1 no conjugated proteins)

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

8

"CHunk norris hates PUNKSS"

Urease-positive bugs
-Cryptococcus
-H. pylori
-Proteus
-Ureaplasma
-Nocardia
-Klebsiella
-S. epidermidis
-S. saprophyticus

9

Pigment-producing bacteria
-"Israel has Yellow sand" = ?
"Gold" = ?
Blue-green pigment = ?
Red pigment = ?

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

10

Which bacteria Promotes evasion of host immune response?

Name the 3 bacteria associated with this.

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)

11

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

Protein A

12

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

IgA protease

13

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

M protein

14

"Some Killers Have Pretty Nice Capsules"
- help avoid immune response

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

15

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

Endotoxin

16

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

Exotoxin

17

Inhibit Protein Synthesis
-Diphtheria toxin

Corynebacterium diphtheriae (Exotoxin)

18

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

Pseudomonas aeruginosa (Exotoxin)

19

Inhibit protein synthesis
Shiga-like toxin (SLT)

Enterohemorrhagic E. Coli (EHEC) (exotoxin)

20

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

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

21

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

Bacillus Anthracis

22

-Cholera toxin
-Overactives adenylate cyclase (increased cAMP) by permanently activiting Gs -> increased Cl- secretion in gut and H2o efflux
-Voluminous "rice-water" diarrhea

Vibrio Cholerae

23

Name 1 bacteria that Inhibit phagocytic ability

Bordetella pertussis

24

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

Bordetella pertussis

25

Name 2 bacteria that Inhibit Release of Neurotransmitter

Clostridium tetani
Clostridium botulinum

26

Which bacteria is associated with:
-Lock jaw & muscle rigidity
-toxin prevents release of inhibitory (GABA and glycine) neurotransmitters in spinal cord

Clostridium Tetani
- tetanospasmin (toxin)

27

Which bacteria is associated with:
-Flaccid paralysis, floppy baby;
-toxin prevents release of stimulatory (ACh) signals at neuromuscular junction -> flaccid paralysis

Clostridium Botulinum
-botulinum toxin

28

Which 3 bacteria's increase fluid secretion?

Enterotoxigenic E. Coli (EHEC)
Bacillus anthracis
Vibrio cholerae

29

What vaccine is used for clostridium tetani?

tatanus toxoid

30

Name the 2 lyse cell membranes bacteria.

Clostridium perfringens
Streptococcus pyogenes

31

-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)

Clostridium perfringens

32

Toxin: Streptolysin O
Mechanism: Protein degrades cell membrane

Streptococcus pyogenes

33

What are the 2 bacteria that cause Superantigens causing shock?

Staphylococcus aureus
Streptococcus pyogenes

34

What are symptoms of Toxic shock syndrome?

Fever, rash, and shock
(other toxins- scalded skin syndrome with exfoliative toxin and food poisoning with enterotoxin)

35

What is the toxin associated with Staphylococcus aureus?

Toxic shock syndrome toxin (TSST-1)

36

What is the toxin associated with Streptococcus pyogenes?

Exotoxin A

37

A lipopolysaccharide found in outer membrane of gram-negative bacteria

Endotoxin

38

ENDOTOXIN

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

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

Lag phase
Exponential growth phase
Stationary phase
Death phase

40

Describe the lag phase of the bacterial growth curve.

Metabolic activity without division

41

Describe the exponential/log phase of the bacterial growth curve

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

42

Describe the stationary phase of the bacterial growth curve

nutrient depletion slows growth. Spore formation in some bacteria

43

Describe the death phase of the bacterial growth curve

Prolonged nutrient depletion and buildup of waste products lead to death

44

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

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

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

H. Influenzae

46

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"

N. Gonorrhoeae & N. Meningitidis

47

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

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

48

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

B. pertussis
(Bordet for BORDETella

49

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

C. diphtheriae

50

Media used for isolation: Eaton's agar

M. pneumoniae

51

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

Lactose-fermenting enterics

52

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

Legionella

53

SABouraoud's agar.
-("Sab's a FUN Guy!")

Fungi

54

Name 5 stains for bacteria.

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

55

What is the Giemsa stain used for?
("Certain Bugs Really Try my Patience")

Chlamydia, borrelia, rickettsiae, trypanosomes, plasmodium

56

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

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

57

What is the Ziehl-Neelsen used for ?
(My Nook is Fast)

Acid-fast organisms (Nocardia, mycobacterium)

58

What is the india ink used for?

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

59

What is the silver stain used for ?

Fungi (e.g. pneumocystis), legionella, helicobacter pylori
("The Fun Helicopeter Silver Lining")

60

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

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