Bacteriology Lecture 16 Host Response To Bacterial Structures

Front 1

The type of host defenses encountered by pathogenic bacteria is influenced by what

Back 1

Both the site of infection and the life style of the bacteria

Front 2

What is the lifestyle of extracellular pathogens

Back 2

Remain attached to the outside of host cells, usually via pili or fimbriae. May cause disease via secretion of toxins (Vibrio cholerae)
Can be invasive via spread through tissue (between cells) (Pseudomonas aeruginosa)

Front 3

Whis is the lifestyle of facultatively intracellular for epithelial, endothelial cells, or other non-professional phagocytes pathogens

Back 3

These may live within or outside of host cells
May provide a protected niche for bacterial replication or persistence
If invasion is from cell to cell, bacteria can dodge extracellular defenses (Shigella spp)

Front 4

What are two examples of obligate intracellular pathogens

Back 4

Chlamydia spp; Rickettsia

Front 5

What is the lifestyle of facultatively intracellular for phagocytes pathogens

Back 5

Avoid being killed by the host's first line of defense. Can utilize phagocyte to disseminate through the body (Salmonella, Legionella, Mycobacterium tuberculosis)

Front 6

Where are the common sites of infection

Back 6

Skin, Respiratory, Gastrointestinal, Urinary tract, reproductive tract, systemic

Front 7

What are host innate defenses

Back 7

Nonspecific inhibitory agents or physiological conditions encountered upon a pathogen's entry into the host (body-site dependent)

Front 8

Who are the resident phagocytes of monocyte/macrophage lineage in innate defense

Back 8

Alveolar macrophages, liver Kupffer cells, brain microglial cells, lymph node and splenic macrophages, kidney mesangial cells, synovial A cells

Front 9

How do innate defense cells uptake and kill bacteria

Back 9

Uptake of bacteria by resident phagocytes is via specific receptors.
Killing mechanisms include acidification of the phagolysosome; production of toxic oxygen species; nitric oxide; antimicrobial peptides

Front 10

What is one of the most important functions of first line macrophages

Back 10

Release of cytokines and chemokines that initiate an inflammatory response. Signaling through TLRs causes secretion of pro-inflammatory cytokines

Front 11

What are two ways bacterial pathogens defend against the first-line macrophage defense

Back 11

Being facultatively intracellular for professional phagocytes (lyse the phagosome membrane, modify phagolysosomal environment, or inhibit acidification)
Inducing apoptosis which causes programmed death of phagocytes

Front 12

What are the bacterial advantages of inducing apoptosis in phagocytes

Back 12

Inactivation of killing potential, Reduction in the number of defenders, No induction of normal cellular signaling processes of cytokine and chemokine signaling of necrotic death

Front 13

What is O2 independent killing by PMNs

Back 13

Release of lysosomal enzymes (collagenase, elastase) which damage tissue and enhance the inflammation process; also antimicrobial peptides

Front 14

What is O2 dependent killing by PMNs

Back 14

NADPH oxidase plus glucose results in superoxide anion

Front 15

What may happen if dead bacteria aren't degrade or removed

Back 15

Granulomas may occur, and more damage is inflicted on host tissue

Front 16

What are the pyogenic bacteria

Back 16

Pus forming bacteria that give rise to a strong inflammatory response, which does not immediately clear infection and thus results in pus

Front 17

What does complement do

Back 17

Opsonizes bacteria for PMN uptake and can directly kill gram-negative bacteria by direct lysis

Front 18

What are the alternative pathway and mannose-binding lectin pathway

Back 18

Pathways that are active early in infection, when specific antibody is not there

Front 19

What is the classical pathway

Back 19

Antibody is required bound to target for activation to occur

Front 20

Deposition of what is critical for uptake of bacteria by phagocytes

Back 20

C3b

Front 21

Which components form the membrane attack complex

Back 21

C5b, C6,C7,C8, and C9. The MAC can lyse gram-negative bacteria

Front 22

What do almost all principal bacterial pathogens that cause pneumonia and meningitis have in common

Back 22

Anti-phagocytic polysaccaride capsules. Nonencapsulated variants of these organisms are usually avirulent

Front 23

What is the M protein of Group A streptococci

Back 23

Sterically hinders complement from depositing on bacterial surfaces by binding fibrinogen and its breakdown product fibrin to its surface

Front 24

What do porins of Neisseria gonorrhoeae bind

Back 24

Host proteins that are negative regulators of complement activation (Factor H, C4bp)

Front 25

How do Neisseria sp, Haemophilus influenzae type b, and Streptococcus pneumoniae avoid antibodies

Back 25

They produces IgA1 protease

Front 26

What is a feature of the group B capsule of N. meningitidis

Back 26

It is poorly immunogenic, which challenges vaccine development

Front 27

What is the cause of gram negative shock

Back 27

Endotoxin

Front 28

What is endotoxin

Back 28

The lipid component of LPS that acts on macrophages. Nanogram amounts produce fever via release of Il-1 and TNF from macrophages

Front 29

What do large amounts of endotoxin produce

Back 29

The dramatic physiologic effects associated with inflammation (hypotension, decreased PMN and platelet counts, hemorrhage, DIC)

Front 30

When is endotoxin active

Back 30

Always, whether it is a free molecule, within cell wall fragments, or on intact gram-negative organisms

Front 31

What does LPS induced release of TNF-alpha by macrophages induce

Back 31

Protection at the local level, but catastrophic effect when released systemically

Front 32

What can endotoxin in the blood stream cause

Back 32

Rapid and irreversible shock. Venules in all tissues are simultaneously affected, which induces shock that can lead to organ failure and death

Front 33

What is important to remember about antibody to endotoxin

Back 33

It does not effectively neutralize endotoxin activity

Front 34

What can gram-positive bacterial infection lead to

Back 34

Septic shock due to the bioactivity of peptidoglycan fragments and other cell wall determinants, which leads to release of cytokines