Chapter 1: Bacterial Metabolism

Question 1

What 3 enzymes break down toxic oxygen products?

Answer 1

1) Catalase
2) Peroxidase
3) Superoxide dismutase

Question 2

What toxic products can be formed by reactive oxygen? (3)

Answer 2

1) hydrogen peroxide H2O2
2) superoxide radicals O2-
3) hydroxyl radical OH.

Question 3

Catalase - function?

Answer 3

breaks down hydrogen peroxide to water and oxygen:

H2O2 –> H2O + O2

Question 4

What enzyme breaks down hydrogen peroxide to water and oxygen?
H2O2 –> H2O + O2

Answer 4

Catalase

Question 5

Peroxidase - function?

Answer 5

breaks down hydrogen peroxide to water

Question 6

What enzyme breaks down hydrogen peroxide to water?

Answer 6

Peroxidase

Question 7

Superoxide dismutase - function?

Answer 7

Breaks down superoxide radical to hydrogen peroxide and oxygen:
O2- + O2- + 2H+ –> H2O2 + O2

Question 8

What enzyme breaks down superoxide radical to hydrogen peroxide and oxygen?
O2- + O2- + 2H+ –> H2O2 + O2

Answer 8

superoxide dismutase

Question 9

obligate aerobes - defn

Answer 9

Use an oxygen-dependent system to generate ATP, with oxygen as the final electron acceptor in the electron transport chain

Question 10

obligate aerobes - enzymes?

Answer 10

express catalase, peroxidase, and superoxide dismutase to prevent free radical damage

Question 11

which type of bacteria express catalase, peroxidase, and superoxide dismutase?

Answer 11

obligate aerobes, to prevent free radical damage

Question 12

Examples of obligate aerobes (4)

Answer 12

“Nagging Pests Must Breathe”

1) Nocardia
2) Pseudomonas aeroginosa
3) MycoBacterium tuberculosis

Question 13

What kind of metabolism does Nocardia use?

Answer 13

obligate aerobe

Question 14

What kind of metabolism does Pseudomonas aeroginosa use?

Answer 14

obligate aerobe

Question 15

What kind of metabolism does Mycobacterium tuberculosis use?

Answer 15

obligate aerobe

Question 16

Reactivation of what obligate aerobic microbe has a predilection for the apices of the lung?

Answer 16

M. tuberculosis (e.g. after immune compromise or TNFa inhibitor use), because apices of the lung have the highest PO2

Question 17

What obligate aerobe is seen in burn wounds, complications of diabetes, nosocomial pneumonia, and pneumonia in cystic fibrosis patients?

Answer 17

Pseudomonas aeroginosa

Question 18

Pseudomonas aeroginosa is seen in which cases? (4) (hint: P. aeroginosa is an obligate aerobe)

Answer 18

1) burn wounds
2) complications of diabetes
3) nosocomia pneumonia
4) pneumonias in cystic fibrosis patients

Question 19

obligate anaerobe - defn

Answer 19

cannot survive in the presence of oxygen

Question 20

obligate anaerobe - enzymes?

Answer 20

Lack catalase, peroxidase, and superoxide dismutase, and are thus susceptible to oxidative damage

Question 21

3 characteristics of obligate anaerobes?

Answer 21

1) generally foul smelling (short-chain fatty acids)
2) difficult to culture
3) produce gas in tissue (CO2 and H2)

Question 22

Examples of obligate anaerobes (3)

Answer 22

Anaerobes “Can’t Breathe Air”

1) Clostridium
2) Bacteriodes
3) Actinomyces

Question 23

What kind of metabolism does Clostridium use?

Answer 23

obligate anaerobe

Question 24

What kind of metabolism does Bacteriodes use?

Answer 24

obligate anaerobe

Question 25

What kind of metabolism does Actinomyces use?

Answer 25

obligate anaerobe

Question 26

Where are anaerobes found? (2)

Answer 26

1) normal flora in GI tract

2) pathogenic elsewhere

Question 27

Are aminoglycosides effective against anaerobes? Why or why not?

Answer 27

AminOglycosides are ineffective against anaerobes because these antibiotics require O2 to enter into the bacterial cell.

Question 28

Facultative anaerobes - defn

Answer 28

Use oxygen when present (have an electron transfer chain, catalase, superoxide dismutase), but can grow in the absence of oxygen by using fermentation in the absence of oxygen

Question 29

Microaerophilic bacteria (aerotolerant anaerobes) - defn

Answer 29

use fermentation and have no electron transport chain, but they can tolerate low amounts of oxygen because they have superoxide dismutase but no catalase

Question 30

Microaerophilic bacteria (aerotolerant anaerobes) - enzymes?

Answer 30

have superoixde dismutase, but lack catalase

Question 31

obligate intracellular - defn

Answer 31

not capable of their own metabolic pathways for ATP synthesis, and thus must steal ATP from their host

Question 32

obligate intracellular - examples (2)

Answer 32

“Stay inside (cells) when it is Really Cold”

1) Rickettsia
2) Chlamydia

Question 33

facultative intracellular - examples (8)

Answer 33

“Some Nasty Bugs May Live FacultativeLY”

1) Salmonella
2) Neisseria
3) Brucella
4) Mycobacterium
5) Listeria
6) Francisella
7) Legionella
8) Yersinia pestis

Question 34

facultative intracellular - examples (8)

Answer 34

“Listen Sally Yer Friend Bruce May Leave Now”

1) Listeria monocytogenes
2) Salmonella typhi
3) Yersinia pestis
4) Francisella tularensis
5) Brucella
6) Mycobacterium
7) Legionella
8) Neisseria

Question 35

Which organisms are catalase positive?

Answer 35

“PLACESS” for your cats

1) Pseudomonas
2) Listeria
3) Aspergillus
4) Candida
5) E.coli
6) S. auereus
7) Serratia

Question 36

Patients with what disease have recurrent infections with catalase positive organisms? Why?

Answer 36

chronic granulomatous disease
These patients lack NADPH oxidase (required for respiratory burst) in phagocytes, so they cannot kill bacteria. Catalase-positive bacteria can degrade H2O2 before it can by converted to microbicidal products by myeloperoxidase.