How Bacterial Pathogens Penetrate Host Defenses

Question 1

resist the host’s defenses by impairing phagocytosis,
the process by which certain cells of the body engulf and destroy microbes.

Answer 1

Capsules

Question 2

The cell walls of certain bacteria contain chemical substances that contribute to virulence.

Answer 2

Cell wall components

Question 3

Streptococcus pyogenes produces a heat-resistant and
acid-resistant protein called ________.

Answer 3

M protein

Question 4

Neisseria gonorrhoeae grows inside human epithelial cells and leukocytes. These bacteria use fimbriae and an outer membrane protein called _____to attach to host cells. Following attachment by both Opa and fimbriae, the host cells take in the bacteria.

Answer 4

Opa

Question 5

✓The waxy lipid (___________) that makes up the cell wall of Mycobacterium tuberculosis also increases virulence by resisting digestion by phagocytes, and the bacteria can even multiply inside phagocytes.

Answer 5

mycolic acid

Question 5

Enzymes used by pathogens to penetrate the host:

Answer 5

Coagulases
Bacterial kinases
Hyaluronidase
Collagenase
IgA Proteases

Question 6

➢refers to a specific defensive response of the body to an infection or to antigens.
➢ In the presence of antigens, the body produces proteins called antibodies, which bind to the antigens and inactivate them or target them for destruction by phagocytes.

Answer 6

Adaptive Immunity

Question 7

➢Changes in surface antigens that occur in a microbial population.
➢ By the time the body mounts an immune response against a pathogen, the pathogen has already altered its antigens and is unaffected by the antibodies.

Answer 7

Antigenic Variation

Question 8

Microbes Capable of Antigenic Variation:

Answer 8

✓Influenza virus, the causative agent of influenza (flu)
✓Neisseria gonorrhoeae, the causative agent of gonorrhea
✓Trypanosoma brucei gambiense, the causative agent of African trypanosomiasis (sleeping sickness)

Question 9

How Bacterial Pathogens Damage Host
Cells Four Basic Ways:

Answer 9

1) By using the host’s nutrients.
2) By causing direct damage in the immediate vicinity of the invasion.
3) By producing toxins, transported by blood and lymph, that damage sites far removed from the original site of invasion.
4) By inducing hypersensitivity reactions

Question 10

Iron is required for the growth of most pathogenic bacteria, to obtain iron, some pathogens secrete proteins called _______

Answer 10

siderophores

Question 11

➢ poisonous substances that are produced by certain
microorganisms.
➢They are often the primary factor contributing to the
pathogenic properties of those microbes.

Answer 11

Toxins

Question 12

the capacity of microorganisms to produce toxins.

Answer 12

Toxigenicity

Question 13

Toxins transported by the _______or _______can cause serious, and sometimes fatal, effects.

Answer 13

blood; lymph

Question 14

• refers to the presence of toxins in the blood

Answer 14

toxemia

Question 15

Two General Types of Toxins:

Answer 15

Endotoxin and Exotoxin

Question 16

➢produced inside some bacteria (mostly gram-negative) as part of their growth and metabolism and are secreted by the bacterium into the surrounding medium or released following lysis.

Answer 16

Exotoxins

Question 17

Toxins are secreted to the outside of the bacterial cells that produce them.

Answer 17

Exotoxin

Question 18

Three types of Exotoxin:

Answer 18

A-B Toxins
Membrane-Disrupting Toxins
Superantigens

Question 19

➢they consist of two parts designated A and B, both of which are polypeptides.

Answer 19

A-B Toxins

Question 20

In A-B toxins, the A part is the ________ component, and the B part is the ________component.

Answer 20

active (enzyme); binding

Question 21

Most exotoxins are ________.

Answer 21

A-B Toxins

Question 22

A type of exotoxin that cause lysis of host cells by disrupting their plasma membranes.

Answer 22

Membrane-Disrupting Toxins

Question 23

Type of Exotoxin:
➢antigens that provoke a very intense immune response.
➢bacterial proteins that combine with a protein on macrophages; this nonspecifically stimulates the proliferation of immune cells called T cell.

Answer 23

Superantigens

Question 24

white blood cells (lymphocytes) that act against foreign
organisms and tissues.

Answer 24

T cells

Question 25

small protein molecules produced by various body
cells, especially T cells, that regulate immune responses and mediate cell-to-cell communication.

Answer 25

Cytokines

Question 26

A toxin that is a part of the outer portion of the cell wall of gram-negative bacteria

Answer 26

Endotoxin

Question 27

The lipid portion of LPS, called ________, is the endotoxin

Answer 27

Lipid A

Question 28

Endotoxins are _________, whereas exotoxins are _________.

Answer 28

lipids; proteins

Question 29

Microorganisms that produce endotoxin:

Answer 29

✓Salmonella typhi (the causative agent of typhoid fever)
✓Proteus spp. (frequently the causative agents of urinary tract infections)
✓Neisseria meningitidis (the causative agent of meningococcal meningitis).

Question 30

Microbes leave the body via specific routes called __________ in secretions, excretions, discharges, or tissue that has been shed.

Answer 30

Portals of Exit

Question 31

Portals of Exit:

Answer 31

Respiratory Tract
Gastrointestinal Tract
Genitourinary tract
Skin or wound infections
Arthropods and syringes

Question 32

a plasma protein produced by the liver, is converted by coagulases into fibrin, the threads that form a blood clot. The fibrin clot may protect the bacterium from phagocytosis and isolate it from other defenses of the host.

Answer 32

Fibrinogen

Question 33

One of the better-known kinases is ___________, which is produced by such streptococci as ________________.

Answer 33

fibrinolysin (streptokinase); Streptococcus pyogenes

Question 34

Collagenase, produced by several species of ___________, facilitates the spread of gas gangrene.

Answer 34

Clostridium