Bacteria - Metabolism, Transmission, Relationships, Infection Mechanisms, and Invasion

Question 1

What pH do most bacteria grow best at?

Answer 1

a neutral pH (7)

Question 2

In regards to CO2, what type of environment do bacteria grow better?

Answer 2

in an environment containing a small amount (5-10%) of CO2

Question 3

In regards to oxygen, what are the byproducts of the metabolic processes of some bacteria?

Answer 3

highly toxic forms of oxygen such as 2O2 and H2O2

Question 4

In regards to oxygen, how do bacteria live in it?

Answer 4

they either need to have a means of detoxifying oxygen or they need to grow in environments where oxygen does not occur

Question 5

What is 2O2 broken down by?

Answer 5

superoxide dismutase

Question 6

What is H2O2 broken down by?

Answer 6

catalase and peroxidase

Question 7

What are the types of bacteria (in regards to oxygen, i.e anaerobe etc.)

Answer 7

strict aerobes, strict (obligate anaerobes, facultative anaerobes, and microaerophiles

Question 8

What is an example of a strict aerobe?

Answer 8

pink eye in cattle

Question 9

What is an example of a microaerophile?

Answer 9

leptospira

Question 10

What are the sources of infectious agents of bacteria?

Answer 10

animals and humans, and inanimate nature

Question 11

What is the general normal flora for bacteria?

Answer 11

skin, mouth, stomach, small intestine, large intestine, etc.

Question 12

Define incubation period.

Answer 12

period from the time of infection until clinical signs appear

Question 13

What is a convalescent carrier?

Answer 13

those who have recovered from their illness but remain capable of transmitting to others

Question 14

What is a contact carrier?

Answer 14

when you acquire the microorganism from contact with the infected

Question 15

What is subclinical infection?

Answer 15

an infection that is nearly or completely asymptomatic

Question 16

What are some sources of infection?

Answer 16

droplet, dust, ingestion, contact, wounds, injection, via genital tract, transplacental, umbilical, and nosocomial

Question 17

What are heterotrophs?

Answer 17

organisms incapable of using either light or inorganic compounds as an energy source or of using CO2 as a sole carbon source

Question 18

What are saprophytes?

Answer 18

heterotrophs that live on dead or decaying organic matter - most pathogenic bacteria

Question 19

What is a commensal relationship?

Answer 19

doesn’t cause disease

Question 20

What is a opportunist relationship?

Answer 20

normally harmless in their usual environment but cause disease when they gain access to other sites or tissues

Question 21

What is an obligate pathogen?

Answer 21

a parasite that cannot complete its lifestyle without exploiting a suitable host

Question 22

What are Koch’s postulates?

Answer 22

1. the organism must be regularly isolated from cases of the disease
2. it must be grown in vitro in pure culture
3. a pure culture should produce the typical disease when inoculated into a susceptible animal
4. the same organism must be isolated from the experimentally induced disease

Question 23

What are the three components of colonization of mucosal surfaces?

Answer 23

association, adhesion, and invasion

Question 24

What is association?

Answer 24

localization of bacteria on or near the cell surface - they may associate with mucus or exudates, establish small numbers of noncovalent bonds with the surface or respond to chemotactic factors

Question 25

What is bacterial adhesion?

Answer 25

stable, irreversible attachment of a bacterium to a mucosal surface

Question 26

What is bacterial adhesion usually between?

Answer 26

specific surface proteins of the bacterium and carbohydrate-containing molecules on the eukaryottic cell surface or glycocalyx

Question 27

What are hemagglutinins?

Answer 27

molecules which mediate agglutination of erythrocytes that may also function as adhesions

Question 28

What is adhesion greatly affected by?

Answer 28

the electrostatic charge and hydrophobicity of the cell surfaces that interact

Question 29

What is the Derjaguin-Landau and Verwey-Overbeek (DLVO) theory?

Answer 29

two rigid bodies of like charge approach each other they are affected by attractive and repulsive forces, which vary independently with the distance between the bodies

Question 30

Over what distance is there a net force of attraction?

Answer 30

>10nm

Question 31

Over what distance is there net repulsive force?

Answer 31

1 - 10 nm

Question 32

Over what distance is there a strong attractive force?

Answer 32

distance of less than 1 nm

Question 33

What happens to the presence of repulsive force as the radii of curvature decreases?

Answer 33

the repulsive force is less and may be able to bridge the intermediate zone of repulsive forces and establish a stable receptor-ligand bond

Question 34

What cations help bridge the intermediate zone?

Answer 34

Fe3+ and Ca2+

Question 35

What can proteinaceous adhesions be divided into categorically?

Answer 35

those with fimbrial morphology and those lacking definite shape and size

Question 36

Describe fimbrial adhesions.

Answer 36

filamentous structures that vary from 2-7 nm in diameter and which extend up to 4 micrometers from the bacterial surface

Question 37

Describe type 1 fimbriae.

Answer 37

closely related to F6 fimbriae relatively rigid structure, a uniform cross-sectional diameter, and an axial hole subunits are arranged as a helical structure tends to aggregate into highly ordered, parallel bundles

Question 38

Describe nonfimbrial proteinaceous adhesions.

Answer 38

adhesions that lack a definite structure and often take the form of secreted proteins or proteins associated with the outer membrane

Question 39

What is an example of a species that has a nonfimbrial proteinaceous adhesion?

Answer 39

staphylococcus aureus

Question 40

How does lipoteichoic acid bind to eukaryotic cells?

Answer 40

by interacting with a fibronectin receptor

Question 41

What is expression of bacterial adhesions affected by?

Answer 41

the conditions under which the organisms grow both in vitro and in vivo

Question 42

When do type 1 fimbriae grow?

Answer 42

in cultures of organisms grown in static broth culture beyond late log phase but they are not produced in cultures grown on agar media

Question 43

What do mucosal cells of host tissues have on their surfaces and what do they do?

Answer 43

glycoproteins and glycolipids which act as receptors for hormones, nutrients, and a variety of other molecules as well as carbohydrate receptors that provide binding sites for bacterial adhesions and toxins

Question 44

What is an extracellular parasite?

Answer 44

organisms that reside out of eukaryotic cells

Question 45

What is a facultative intracellular parasite?

Answer 45

an organism that has the capacity to grow and survive both inside and outside of eukaryotic cells

Question 46

Do extracellular parasites or facultative intracellular parasites live longer?

Answer 46

facultative intracellular parasites

Question 47

What is an obligate intracellular parasite?

Answer 47

parasites that can only grow within cells

Question 48

Provide an example of a parasite that can gain entry by trauma or puncture.

Answer 48

Clostridium tetani

Question 49

Provide an example of a parasite that can gain entry by endocytosis.

Answer 49

Salmonella typhimurium

Question 50

Provide an example of a parasite that can gain entry via receptor mediated endocytosis.

Answer 50

Chlamydia psittaci

Question 51

Provide an example of a parasite that can gain entry via uptake by antigen sampling sites.

Answer 51

Salmonella sp

Question 52

Provide an example of a parasite that can gain entry via disruption by cytotoxins.

Answer 52

Salmonella sp

Question 53

Provide an example of a parasite that can gain entry via direct penetration.

Answer 53

Leptospira

Question 54

Which of the types of invasion is not a true invasion?

Answer 54

trauma or puncture

Question 55

Explain the process of endocytosis.

Answer 55

eukaryotic cells invaginate and engulf the bacteria in a membrane-bbound vacuole that is similar to the phagocytic vacuole of neutrophils and macrophages

Question 56

What specific structure is required for endocytosis?

Answer 56

contractile proteins