Microbiology Exam I

Front 1

Endotoxin is also called _ and it is part of _

Back 1

LPS, part of gram neg.outer membrane

Front 2

Toxic portion of LPS is _

Back 2

Lipid A - released and becomes toxic after death of cell

Front 3

LPS is heat _

Back 3

Stable, and not strongly immunogenic

Front 4

Mechanism of LPS

Back 4

LPS activates macrophages and stimulates release of TNF and IL (IL1 - major mediator of fever). Macrophage activaion leads to tissue damage - can lead to shock and DIC

Front 5

A-B components of exotoxin

Back 5

B - binds to specific cell receptors to facilitate entry of component A
A - active toxic component

Front 6

Cytolysins

Back 6

Damage cells from outside (alpha toxin of S. aureus makes pores in membranes)

Front 7

Which toxin can be used as vaccine

Back 7

Exotoxin - can be modified and turned into still immunogenic but no longer toxic

Front 8

Capsule

Back 8

-Non essential
-Slime, polysaccharides
-Both gram + and gram - bacteria
-Protects bacteria against phagocytosis, immunogenic

Front 9

Outer membrane

Back 9

-Gram neg. bacteria ONLY
-Has LPS (endotoxin), lipid A (toxic),

Front 10

Whats present in cell wall in gram + only?

Back 10

Teichoic acids - stimulate TNF and IL 1 , also for attachment

Front 11

Cell wall

Back 11

Consists of peptidoglycan
-Gram + thick, gram neg. thin
-Consists of NAG and NAM
-Provides rigid support, shape and protection from osmotic damage
-Confers Gram reaction
-Inhibited by penicillin

Front 12

Periplasmic space

Back 12

-Gram neg. only
-"storage space" between inner and outer membranes
-Contains important enzymes ( like beta-lactamase)

Front 13

Pili

Back 13

-Also called fimbriae
-Can be common, sex or virulent
-Mostly in gram neg. bacteria
-Used for attachment and in conjugation

Front 14

Flagellum

Back 14

-Both gram + and gram neg.
-Can be used for motility

Front 15

Lag phase

Back 15

-Initial phase of bacterial growth
- Number of cells in the beginning is same as at the end

Front 16

Log phase

Back 16

-Rapid exponential growth

Front 17

Stationary phase

Back 17

Nutrients are being used up and toxic products begin to accumulate
-Number of new cells = number of dying cells

Front 18

Obligate aerobes

Back 18

-Require oxygen
-No fermentation
-Produces superoxide dismutase

Front 19

Microaerophilic (example of organism)

Back 19

Requires low but not full oxygen tension
- Campylobacter, Helicobacter

Front 20

Facultative anaerobes

Back 20

Will respire aerobically when oxygen is present and will use fermentation when oxygen is not - most bacteria

Front 21

Obligate anaerobes

Back 21

- Lack superoxide dismutase and catalase
-Cannot use electron chain
-Use fermentation only

Front 22

Staphylococcus:
-gram _
-catalase_
-arranged in _

Back 22

-Positive
-Positive
-Clusters

Front 23

Staph aureus - hemolysis and coagulase

Back 23

Coagulase positive
Beta hemolysis

Front 24

Staph aureus virulence factors and lab ID

Back 24

-Protein A
-TSST-1
-Enterotoxins
-Exfoliatins
-Cytolysins

Front 25

Common diseases of Staph Aureus

Back 25

-Infective endocarditis (IV drug users)
-Abscesses
-Toxic shock syndrome
-Gastroenteritis
-Supurrative lesions
-Osteomyelitis

Front 26

Staph aureus distinguishing characteristics

Back 26

-Beta hemolysis, clusters of yellow gram + cocci on blood agar
-Catalase + , coagulase +
-Ferments mannitol on mannitol salt agar

Front 27

Staph aureus reservoir

Back 27

Normal flora of nasal mucosa and skin

Front 28

Transmission of staph aureus

Back 28

-Sneezing and hands contact
-Surgical wounds
-Foods associated with food poisoning

Front 29

Pathogenesis of staph aureus

Back 29

-Protein A inhibits phagocytosis, binds Fc portion of Ab
-Enterotoxin (A-E) - heat stable
-TSST- 1
-Coagulase - converts fibrinogen to fibrin clot
-Cytolytic toxins - toxin alpha of staph . aureus punches holes in cell membranes of human host
Exfoliatins - scalded skin syndrome and impetigo

Front 30

Staph. aureus gastroenteritis

Back 30

Enterotoxins preformed in food
-2-6 hours after ingestion - nausea, vomitting followed by diarrhea

Front 31

Treatment of staph infection

Back 31

Resistant to penicillin and most antibiotics - except methycillin
MRSA - resistant to methycillin too - use vancomycin

Front 32

Streptococcus:
Gram _
Catalase_
Look like_

Back 32

Gram neg.
Catalase neg.
Look like pairs or chains of cocci

Front 33

S. pyogenes
-Group _
-Hemolysis _
-Sensitive to _

Back 33

A
Beta hemolysis
Sensitive to bacitracin

Front 34

Reservoir for Strep. pyogenes

Back 34

Human throat and skin

Front 35

Transmission of Strep. pyogenes

Back 35

-Direct contact or respiratory droplets

Front 36

Pathogenesis for Strep. pyogenes

Back 36

M protein - antiphagocytic, used to type group A strep

Front 37

Toxins of strep. pyogenes

Back 37

Streptolysin O - immunogenic
Streptolysin S - non immunogenic
Both are hemo and cytolytic

Front 38

Spreading factors for Strep. pyogenes

Back 38

Streptokinase - breaks down fibrin clot
Strep. DNAse - liquiefied pus, extension of lesion
Hyaloronidase - important for spread in cellulitis