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Flashcards in Micro Deck (127):
1

Chocolate Agar
- Factors V (NAD+) and X (hematin)

H. influenzae

2

Thayer-Martin Agar

Neisseria gonorrhoeae and meningitidis

3

Bordet Gengou Agar (potato) or Regan Lowe Medium (charcoal, blood, Abx)

Bordatella pertusssis

4

Tellurite Agar, Loffler Medium

C. diptheriae

5

Lowenstein-Jensen Agar

M. tuberculosis

6

Eaton Agar (requires cholesterol)

M. pneumoniae

7

MacConkey Agar
- Fermentation --> acid --> pink colonies

Lactose-fermenting enterics (E. coli, Klebsiella)

8

EMB Agar

E. coli

9

Charcoal yeast extract agar buffered with cysteine and iron

Legionella

10

Sabouraud Agar

Fungi

11

Yellow "sulfur" granules

Actinomyces israelii

12

Yellow pigment

Staph aureus

13

Blue-green pigment

Pseudomonas aeruginosa

14

Red pigment

Serratia marcescens

15

Protein A
- S. aureus

Binds Fc region of IgG --> prevents opsonization and phagocytosis

16

IgA Protease
- S. pneumo, H. flu type B, Neisseria

Cleaves IgA to colonize respiratory mucosa

17

M Protein
- Group A Strep

Prevents phagocytosis
- Molecular mimicry
- AI response in rheumatic fever

18

Type III Secretion System (Injectisome)
- Pseudomonas, Salmonella, Shigella, E. coli

Needle-like protein appendage facilitating direct delivery of toxins from certain gram negative bacteria to eukaryotic host cell

19

Transformation
- S. pneumo, Hib, Neisseria

Take up naked DNA from environment
- Add deoxyribonuclease --> degrades naked DNA --> no transformation seen

20

Conjugation

F+ = sex pilus, conjugation
F- = no plasmid
Hfr = F+ plasmid incorporated into bacterial chromosomal DNA (can bring flanking DNA)

21

Transposition

Segment of DNA jumps from one location to another (can bring flanking DNA)
- Ex. vanA gene from vancomycin-resistant Enterococcus to S. aureus

22

Generalized Transduction

Lytic phage infects bacterium --> cleavage of bacterial DNA --> parts of bacterial chromosomal DNA may become packaged in phage capsid --> phage infects another bacterium --> transfers genes

23

Specialized Transduction

Lysogenic phage infects bacterium --> viral DNA incorporates into bacterial chromosome --> phage DNA excised with some flanking bacterial genes --> DNA packaged into phage capsid --> infects another bacterium

24

Spore Forming Bacteria
- highly resistant to heat and chemicals
- dipicolinic acid in core
- must autoclave to kill

- Bacillus anthracis (anthrax)
- Bacilus cereus (food poisoning)
- C. botulinum (botulism)
- C. difficile (pseudomembranous colitis)
- C. perfringens (gas gangrene)
- C. tetani (tetanus)

25

C. diphtheriae
- Diphtheria toxin

ADP-ribosylation --> inactivates EF-2 --> no protein synthesis
- Pharyngitis with pseudomembranes in through and severe LAD (bull neck)

26

Pseudomonas aeruginosa
- Exotoxin A

ADP-ribosylation --> inactivates EF-2 --> no protein synthesis
- Host cell death

27

Shigella spp.
- Shiga toxin

Inactivates 60S ribosome by removing adenine from rRNA
- GI mucosal damage --> dysentery
- Enhances CK release --> HUS
- INVADES host cells

28

EHEC
- Shiga-like toxin

Inactivates 60S ribosome by removing adenine from rRNA
- Enhances CK release --> HUS (O156:H7)
- Does NOT invade host cells

29

ETEC
- Heat labile and heat stable toxin

Heat LABILE: overactivates adenylate cyclase --> increased cAMP --> increased Cl- secretion in gut and H2O efflux
Heat STABLE: overactivates guanylate cyclase --> increased cGMP --> decreased reabsorption of NaCl and H2O in gut
- Watery diarrhea

30

Bacillus anthracic
- Edema toxin

Mimics adenylate cyclase enzyme --> increased cAMP
- Edematous borders of black eschar in cutaneous anthrax

31

Vibrio cholerae
- Cholera toxin

Permanently activates Gs --> overactivates adenylate cyclase --> increased cAMP --> increased Cl- secretion in gut and H2O efflux
- Voluminous rice-water diarrhea

32

Bordatella pertussis
- Pertussis toxin

Disables Gi --> overactivates adenylate cyclase --> increases cAMP --> impairs phagocytosis --> permits survival of microbe
- Whooping cough

33

Clostridium tetani
- Tetanospasmin

Protease that cleaves SNARE --> inhibits vesicular fusion --> no NT release
- Spastic paralysis, risus sardonicus, "lockjaw"
- Prevents release of inhibitory (GABA and glycine) NT from Renshaw cells in spinal cord

34

Clostridium botulinum
- Botulinum toxin

Protease that cleaves SNARE --> inhibits vesicular fusion --> no NT release
- Flaccid paralysis, floppy baby
- Prevents release of stimulatory (ACh) at NMJ

35

Clostridium perfringens
- Alpha toxin

Phospholipase (lecithinase) --> degrades tissue and cell membranes
- Myonecrosis (gas gangrene)
- Hemolysis ("double zone" of hemolysis on blood agar)

36

Streptococcus pyogenes
- Streptolysin O
- Exotoxin A

Streptolysin O: degrades cell membrane --> Lyses RBC --> contributes to beta-hemolysis
- Host Ab against toxin (ASO) used to dx rheumatic fever
Exotoxin A: binds to MHC II and TCR outside of Ag binding site --> overwhelming release of IL-1, IL-2, IFN-gamma, TNF-alpha --> toxic shock syndrome

37

Staph aureus
- Toxic shock syndrome toxin (TSST-1)
- Exfoliative toxin
- Enterotoxin

- TSST-1: binds to MHC II and TCR outside of Ag binding site --> overwhelming release of IL-1, IL-2, IFN-gamma, TNF-alpha --> toxic shock syndrome
- Exfoliative toxin: scalded skin syndrome
- Enterotoxin: food poisoning

38

Endotoxin

- Macrophage activation --> IL-1/6 (fever), TNF-alpha (fever and hypotension), NO (hypotension)
- Complement activation --> C3a (HA release --> hypotension, edema), C5a (neutrophil chemotaxis)
- Tissue factor activation --> coagulation cascade --> DIC

39

Catalase positive

Staph

40

Coagulase positive

Staph aureus

41

Novobiocin resistant

Staph saprophyticus

42

Novobiocin Sensitive

Staph epidermidis

43

Catalase negative

Strep

44

Alpha hemolytic
- Partial reduction --> greenish/brown w/o clearing around growth

Strep viridians, Strep pneumo

45

Optochin resistant

Strep viridans

46

Optochin sensitive

Strep pneumo

47

Beta hemolytic
- Complete lysis of RBCs --> clear area surrounding colony on blood agar

Strep agalactiae (Group B), Strep pyogenes (Group A), Staph aureus

48

Bacitracin resitatnt

Group B strep

49

Bacitracin sensititve

Strep pyogenes (Group A)

50

Staph aureus

- Protein A
- TSST-1 (superantigen), exfoliative toxin, enterotoxin

51

Most common cause of septic arthritis in adults

Staph aureus

52

Most common cause of osteomyelitis

Staph aureus

53

R sided (tricuspid) endocarditis in IV drug user

Staph aureus

54

Secondary pneumonia after influenza infection

Staph aureus

55

Staph epidermidis

Normal flora of skin
Prosthetic devices and IV catheters
BIOFILMS

56

Staph saprophyticus

Uncomplicated UTI in young sexually active women (2nd to E. coli)

57

Strep pneumo

Lancet-shaped diplococci
Encapsulated
IgA protease
No virulence without capsule

58

Most common cause of meningitis

Strep pneumo

59

Most common cause of otitis media in children

Strep pneumo

60

Most common cause of pneumonia

Strep pneumo
- Rusty sputum

61

most common cause of sinusitis

Step pneumo

62

Strep pneumo vaccine

- Adults: polysaccharide w/o protein (23 valent) --> T cell independent --> IgM
- Kids: conjugated to protein (7 valent) --> robust response of T cells and B cells --> IgG

63

Strep viridans

Dental caries (mutans and mitis)
Subacute bacterial endocarditis at DAMAGED heart valves (sanguinis)
Makes dextrans --> bind to fibrin-platelet aggregates on damaged heart valves

64

Strep pyogenes (Group A Strep)

PYR +
M protein --> rheumatic fever
ASO titer detects infection
Pharyngitis --> rheumatic fever and PSGN
Scarlet fever

65

Most common cause of erysipelas (rash)

Strep pyogenes

66

Acute Rheumatic Fever
- Strep pyogenes

Polyarthritis, carditis, subcutaneous nodules, erythema marginatu, sydenham chorea

67

Scarlet Fever
- Strep pyogenes

Blanching, sandpaper-like body rash
Strawberry tongue
Circumoral pallor
Erythrogenic toxin +

68

Strep agalactiae (Group B Strep)

- Pneumonia, meningitis, & sepsis in babies
- CAMP factor --> enlarges area of hemolysis formed by S. aureus
- Hippurate test +
- PYR+

69

Most common cause of neonatal meningitis

Strep agalactiae

70

Strep bovis

Subacute endocarditis
COLON CANCER

71

Enterococci

UTI, biliary tract infections, subacute endocarditis
PYR +
VRE --> nosocomial infections
Ca grow in 6.5% NaCl and bile

72

Bacillus anthracis

Spore-forming rod
Anthrax toxin
Polypeptide capsule (D-glutamate)
Cutaneous anthrax --> black eschar
Pulmonary anthrax --> pulmonary hemorrhage, mediastinitis, shock (WOOL, GOAT HAIR)
Edema factor --> increases cAMP --> inhibits phagocytosis
Lethal factor --> protease --> cleaves MAPK --> tissue necrosis

73

Bacillus cereus

Reheated rice syndrome
Spores
Cereulide (preformed toxin)

74

Clostridium tetani
- PUNCTURE WOUND

Tetanospasmin --> blocks release of inhibitory GABA And glycine from Renshaw cells in spinal cord --> spastic paralysis
Rx: antitoxin +/- vaccine booster, diazepam, wound debridement

75

Clostridium botulinum
- Adults: improper food canning (preformed toxin)
- Babies: honey (spores)

Produces heat-labile toxin (protease) that inhibits ACh release --> flaccid paralysis
Rx: antitoxin

76

Clostridium perfringens
- Motorcycle accidents
- Penetrating wound form military combat

Alpha toxin (lecithinase) --> myonecrosis and hemolysis
Spores in undercooked food --> heat-labile enterotoxin --> food poisoning (late onset)

77

Clostridium difficile
- Clindamycin or ampicillin use
- PPI use

Toxin A: enterotoxin --> binds to brush border of gut
Toxin B: cytotoxin --> actin depolymerization --> cytoskeletal disruption --> diarrhea --> pseudomembranous colitis
Dx: stool toxins via PCR
Rx: metronidazole or oral vancomycin

78

Corynebacterium diptheriae

Exotoxin encoded by beta-prophage --> ADP-ribosylation of EF-2 --> inhibits protein synthesis
Psuedomembranous pharyngitis
Dx: metachromatic (blue and red) granules, Elek test+ (toxin)
Black colonies on cystine-tellurite agar

79

Diphtheria vaccine

Toxoid
IgG response against exotoxin B

80

Listeria monocytogenes

Pregnant women
Rocket tails - actin polymerization --> IC movement and cell-to-cell spread
Tumbling motility
Rx: ampicillin

81

Nocardia

Aerobe
Acid fast
Pulmonary infections (IC), cutaneous infections after trauma
Rx: sulfonamides

82

Actinomyces

Anaerobe
Oral/facial abscess
Yellow sulfur granules
PID w/ IUDs
Rx: penicillin

83

Mycobacterium tuberculosis

Caseating granulomas with central necrosis and Langerhans giant cells
Cord factor --> serpentine cord --> inhibits mac maturation, induces release of TNF-alpha
Sulfatides --> inhibit phagolysosomal fusion
Acid fast (mycolic acid)
Lowenstein Jensen medium

84

Mycobacterium leprae

Cool temperatures
Armadillo reservoir
Lepromatous: low cell-mediated immunity, humoral Th2 response, numerous acid fast bacilli
Tuberculoid: high cell-mediated immunity, largely Th1-type immune response, rare acid fast bacilli
Rx: dapsone, rifampin, clofazimine

85

Utilizes maltose

N. meningitidis

86

Doesn't utilize maltose

N. gonorrhoeae
Moraxella

87

Grows in 42 C

Campylobacter jejuni

88

Grows in alkaline media

Vibrio cholerae

89

Produces urease

H. pylori

90

Fast lactose fermenter

Klebsiella
E. coli
Enterobacter

91

Slow lactose fermenter

Citrobacter
Serratia

92

H2S production on TSI agar

Salmonella
Proteus

93

Neisseria

VPN agar (Thayer Martin)
Metabolize glucose
Produce IgA protease
Gonococci: IC (within neutrophils), no vaccine (Ag variation of pilus), Fitz-Hugh-Curtis Syndrome
Meningococci: polysaccharide capsule, maltose fermenter, vaccine, Waterhouse-Friderichsen syndrome

94

Haemophilus influenze

IgA protease
Chocolate agar - V (NAD+), X (hematin)

95

Most common cause of mucosal infections (otitis media, conjunctivitis, bronchitis)

Nontypeable (unencapsulated) H. flu

96

Cause of epiglottitis
- drooling, inspiratory stridor

H. flu

97

Hib vaccine

Type b capsular polysaccharide + PRP conjugated to diptheria toxoid
- Given between 2 and 18 mo

98

Bordatella pertussis

Pertussis toxin (disables Gi)
Tracheal cytotoxin (cleaves cilia epi of resp tract)
Whooping cough
Vaccine (Tdap, DTap)
Lymphocytic infiltrate from immune resopnse

99

Legionella pneumophila

Gram stains poorly - use silver stain
Charcoal yeast extract medium with iron and cysteine
Dx: Ag in urine
HYPONATREMIA
Water sources (AC)
Pneumonia + diarrhea + hyponatremia

100

Legionnaires' Disease
- Legionella pneumophila

Sever pneumonia, fever, GI, and CNS sx
Smokers, chronic lung DZ

101

Pontiac Fever
- Legionella pneumophila

Mild flu-like syndrome

102

Pseudomonas aeruginosa

Non-lactose fermenting
Pyocyanin (blue-green)
Grape-like odor
Endotoxin (fever, shock)
Exotoxin A (inactivates EF-2)
Phospholipase C (degrades cell membranes)
Pyocanin (generates ROS)
Mucoid polysaccharide capsule --> biofilm formation

103

Malignant otitis externa

Pseudomonas
Can spread to mastoid, temporal bones
Increased risk in elderly, IC, DM

104

Ostemyelitis in diabetics and IV drug users

Pseudomonas

105

Most common cause of respiratory failure in CF patients

Pseudomonas
Mucoid polysaccharide capsule --> biofilm formation

106

Burn patients

Pseudomonas

107

Hot tub folliculitis

Pseudomonas

108

Ecythema gangrenosum

Pseudomonas
Rapidly progressive necrotic cutaneous lesion
Seen in IC

109

Proteus mirabilis

Swarming motility
Urease + --> staghorn struvite stones
Fish odor

110

Helicobacter pylori

Flagellated
Catalase +, oxidase +, urease +
Dx: urea breath test, fecal antigen test
Produces ammonia --> alkaline environment
Colonizes stomach antrum
Risk of gastric adenocarcinoma and MALT lymphoma

111

Leptospira interrogans

Spirochete
Water contaminated with animal urine

112

Leptospirosis
- Leptospira interrogans

Flue-like sx, myalgias (CALVES), jaundice, photphobia with conjunctival suffusion (erythema w/o exudate)
Surfers and in tropics (Hawaii)

113

Weil Disease (Icterohemorrhagic Leptospirosis)
- Leptospira interrogans

severe form with jaundice and azotemia from liver and kidney dysfunction, fever, hemorrhage, anemia

114

Borrelia burdorferi

Lyme DZ
Vector: Ixodes deer tick
Reservoir: mouse
NE US
Erythema migrans
AV block
Bells palsy
Encephalopathy
Chronic arthritis

115

Treponema pallidum

Painless chancre
Dark field microscopy
VDRL +
Maculpapular rash on palms and soles
Condyloma lata
VDRL/RPR+, confirm with FTA-ABS
Gummas
Aortitis (vasa vasorum destruction)
Neurosyphilis (tabes dorsalis)
Argyll Robertson pupil
Broad-based ataxia, + Romberg, Charcot joints

116

Congenital Syphilis

rhagades, snuffles, saddle nose, notched teeth, mulberry molars, short maxilla, saber shins, CNIII deafness

117

VDRL false positives

Viral infection
Drugs
Rheumatic fever
Lupus and leprosy

118

Anaplasma spp.

Anaplasmosis
Ixodes tick (live on deer and mice)

119

Bartonella spp.

Immunocompetent --> Cat scratch DZ --> fever, LAD (stellate granulomas w/ central necrosis)
IC --> bacillary angiomatosis --> raised red vascular lesions

120

Borrelia recurrentis

Relapsing fever
Louse (variable surface Ag)

121

Brucella spp.

Brucellosis undulant fever --> organomegaly, osteomyelitis
Unpasteurized dairy, vets, ranchers, slaughter houses

122

Campylobacter

Bloody diarrhea
Feces from infected pets/animals, contaminated meats/foods/hands

123

Chlamydiophila psittaci

Psittacosis
Parrots, other birds

124

Coxiella burnetii

Q fever (no rash)
Aerosols of cattle/sheep amniotic fluid

125

Eherlichia chaffeensis

Ehrlichiosis
Amblyomma (Lone Star tick)

126

Francisella tularensis

Tularemia
Rabbits, ticks, deer flies
Type IV HSN

127

Pasteurella multocida

Cellulitis, osteomyelitis
Animal bite, cats, dogs
Mouse like odor