Lesson 1 And 2

Question 1

The ability of a microbe to damage a host is
called ?

Answer 1

Pathogenicity

Question 2

The bacterial traits that confer pathogenicity are called ?

Answer 2

Virulence factors include Adhesions , capsule and toxins.

Question 3

the relative capacity of a pathogen to damage a host is the
?

Answer 3

Degree of virulence

Question 4

genes are
expressed only when their products are required in a process called?

Answer 4

Phase variation

Question 5

Mobile genetic elements are ?

Answer 5

Bacteriophage
Plasmids
Pathogenicity islands

Question 6

It exist as a commensal in the rumen but when it
transfers to the liver of feedlot cattle it can act as a pathogen that causes hepatic
abscesses.
?

Answer 6

Fusobacterium necrophorum

Question 7

They are Able to adhere to body
surfaces.

Answer 7

Commensal organisms,

Question 8

The composition of the microbial communities?

Answer 8

host-specific and,
within hosts, to be organ- specific

Question 9

primes
the immune system, facilitating a more efficient host response to challenge by
bacterial pathogens

Answer 9

Normal microflora

Question 10

The
microflora of the rumen synthesizes what ?

Answer 10

vitamin K and some of the vitamin B

Question 11

This arise when bacteria that live on the skin or mucous
membranes as harmless commensals take advantage of impaired antimicrobial
defenses of the host and behave as opportunistic pathogens?

Answer 11

Endogenous infections

Question 12

This occur after direct or indirect transmission from an
infected animal or from the environment.

Answer 12

Exogenous infections

Question 13

Pathogens may enter a host through ?

Answer 13

the skin,
the conjunctiva,
the
umbilicus, or
the teat canal

Question 14

The main portals of entry are ?

Answer 14

the mucosae of the
gastrointestinal,
respiratory and
urogenital tracts

Question 15

In bacterial infections, the host may be damaged by?

Answer 15

By bacterial toxins,
by the
inflammatory response elicited by the bacteria or their toxins or, commonly, by both
toxins and inflammatory reactions

Question 16

This may also be a
source of tissue damage?

Answer 16

The immune responses of the host

Question 17

Pathogens that
are able to survive within host cells are grouped into two categories ;

Answer 17

1. strict (obligate)
   intracellular pathogens $ 2. facultative intracellular pathogens

Question 18

These are are obligate intracellular pathogens

Answer 18

Chlamydiae and
rickettsiae

Question 19

It enter and replicate in phagocytic cells

Answer 19

Mycobacterium species

Question 20

It invade and replicate in non-phagocytic epithelial cells

Answer 20

Brucella species,
Uropathogenic E. coli,
Salmonella species
Listeria monocytogenes

Question 21

Pathogens use ________ to attach to host tissues and to resist the flushing
action of body fluids

Answer 21

Adhesins

Question 22

It is subject to phase variation in response to
local conditions.

Answer 22

The expression of adhesins

Question 23

It attach to the
epithelial cells of the urinary bladder

Answer 23

Type 1 fimbriae of uropathogenic E. coli

Question 24

It attach to
epithelial cells in the kidney

Answer 24

P fimbriae

Question 25

It is a transcription factor that moves to the cell nucleus where it up-regulates the expression of a number of pro-inflammatory genes.

Answer 25

factor-kappaB (NF-κB)

Question 26

The binding of complement and antibody to the bacterial surface, thus protecting the bacterium from engulfment by phagocytes and from attack by antimicrobial agents

Answer 26

Capsules interfere with opsonization,

Question 27

Is resistant to phagocytic cells because of its large size.

Answer 27

Biofilm

Question 28

Is composed of polyglutamic acid; it is anti-phagocytic and is regarded as an essential virulence factor.

Answer 28

The capsule of Bacillus anthracis

Question 29

Bacterial toxins have been considered to be of two types:

Answer 29

1. exotoxins 2. endotoxins

Question 30

Produced and secreted by viable bacteria

Answer 30

Exotoxins

Question 31

Are integral constituents of the bacterial cell wall not released until the microorganisms are lysed

Answer 31

Endotoxins

Question 32

Is the lipopolysaccharide (LPS) of the outer leaflet of the outer membrane of Gram-negative bacteria

Answer 32

Endotoxin

Question 33

It is composed of three parts

Answer 33

1. hydrophobic glycolipid (lipid A) 2. hydrophilic polysaccharide composed of a core 3. oligosaccharide and an Opolysaccharide (O antigen)

Question 34

It resides in the lipid A portion.

Answer 34

Toxicity

Question 35

It is released when bacterial cell walls are damaged by the complement system, phagocytes or antimicrobial drugs

Answer 35

Lipopolysaccharide

Question 36

The in vivo effects of endotoxin depend on ?

Answer 36

The amount present in the circulation.

Question 37

High concentrations of circulating endotoxin greatly increase the release of ?

Answer 37

Cytokines

Question 38

It induce fever, activate macrophages and clotting factor XII, and stimulate B cells to divide and produce antibodies.

Answer 38

Released cytokines

Question 39

It stimulate the production of prostaglandins and leukotrienes which are mediators of inflammation

Answer 39

Cytokines

Question 40

It is responsible for the deposition of thrombi in small vessels (disseminated intravascular coagulation) and for a dramatic drop in blood pressure, giving rise to life-threatening endotoxic shock.

Answer 40

LPS

Question 41

Exotoxins can be produced by either ?

Answer 41

Gram-positive or Gram-negative bacteria

Question 42

They are highly antigenic proteins that can induce the production of protective antitoxins

Answer 42

The toxins

Question 43

It is ingested in contaminated food and produces systemic effects.

Answer 43

Clostridium botulinum toxin,

Question 44

possesses toxic enzymatic activity

Answer 44

A subunit

Question 45

Is responsible for binding the exotoxin to specific receptors on the host cell membrane and may help in the transfer of the B subunit across the cell membrane.

Answer 45

B subunit

Question 46

Both tetanus toxin and botulinum toxin have what ?

Answer 46

A–B subunit structure.

Question 47

Categories of exotoxins

Answer 47

(i) toxins that act on the extracellular matrix; (ii) toxins that act on the plasma membrane of their target cells, (iii) toxins that act inside the cells, where they modify signalling pathways or the activities of the cytoskeleton; (iv) toxins that cause dysfunction of the immune system, so-called superantigens.

Question 48

Are capable of detecting conserved molecular ‘patterns’ that are unique to microorganisms and are not expressed by the hosts?

Answer 48

pattern-recognition receptors (PRRs)

Question 49

These microbial ‘patterns’ are present in commensals and pathogens , they are known as ?

Answer 49

pathogen-associated molecular patterns (PAMPs)

Question 50

Mammals possess a family of transmembrane PRRs, called ?

Answer 50

toll-like receptors (TLRs)

Question 51

Can detect the molecular signatures of microbial pathogens, they orchestrate the innate immune responses, and they help to initiate the adaptive immune response

Answer 51

TRLs

Question 52

If an enteric pathogen sequestered in the gall bladder or in lymph nodes and is not excreted in the faeces, the host is described as

Answer 52

latent carrier

Question 53

If the pathogen is shed in faeces, either continuously or intermittently, the host is considered as?

Answer 53

active carrier

Question 54

It secretes a number of toxins that degrade the epithelial barrier and allow the opportunistic pathogen to enter the subepithelial tissues.

Answer 54

Pseudomonas aeruginosa

Question 55

Two routes by which invasive pathogens can breach the epithelial barrier:

Answer 55

by passage through the intercellular spaces (the paracellular route), or by passage through the epithelial cells (the transcellular route).

Question 56

It is induced by specific ligand–receptor interactions at the cell membrane

Answer 56

The zipper mechanism

Question 57

It is induced by effector molecules delivered into the cell by a type III secretory system.

Answer 57

trigger mechanism

Question 58

It is invariably peracute and fatal

Answer 58

Anthrax in ruminants

Question 59

Bacterial infections can be conveniently categorized as

Answer 59

acute, subacute, chronic or persistent

Question 60

It has usually have a short severe clinical course, often a matter of days

Answer 60

Acute infections

Question 61

Produce clinical effects of less intensity

Answer 61

Subacute infections

Question 62

It tends to occur when the host fails to eliminate the pathogen

Answer 62

Chronic infections

Question 63

It occurs in certain sites such as the uriniferous tubules and the CNS in which the effects of cell-mediated and humoral immunity are minimal. Persistent shedding may occur from some of these sites as in bovine leptospirosis, in which leptospires may be shed in urine for more than a year.

Answer 63

Persistence