Bacterial Pathogens - Zahrt

Question 1

How is respiratory divided?

Answer 1

Upper airway and Lower airway

Question 2

Where can bacteria be found in the respiratory system?

Answer 2

In the upper airway. The lower airway is sterile

Question 3

What defenses does the body have to prevent lower respiratory infection?

Answer 3

Size selection
Mucus secretions
Mucociliary elevator
Immune cells and response

Question 4

How do pathogens spread into the lower airway?

Answer 4

Direct inhalation (>10um)
Aspiration from upper airway
Spread along mucus membrane
Direct implantation 
Hematogenous spread

Question 5

From a throat culture, you find a gram negative coccobasillus. What bacteria is this?

Answer 5

Bordetella Pertussis

Question 6

Describe the pathogenesis of bordetella pertussis.

Answer 6

Binds to cilia using pertactin, filamentous hemaglutinin and pili. Pertussis toxin alters adenylate cyclase (G-i alpha) and produces massive amounts of mucus and damages the cilia.

Question 7

What are the three stages of infection for bordetella pertussis?

Answer 7

catarrhal- runny nose, mild coughing, flu-like symptoms

paroxysmal- “barking” coughing fits, vomitting

convalescence- decrease in coughing, no vomitting

Question 8

From a throat culture, you find a gram negative basillus arranged in pallisades. What bacteria is this?

Answer 8

Corynebacterium diptheriae

Question 9

Describe the pathogenesis of corynebacterium diptheriae

Answer 9

Uses pili to attach to upper respiratory tract cells; produces diptheria toxin which modifies EL-2 and prevents protein synthesis.

Forms a pseudo membrane.

Question 10

From a throat culture, you find a gram negative diplococci. What bacteria is this?

Answer 10

Neisseria meningitidis

Question 11

How is neisseria classified by oxidase and catalase tests?

Answer 11

Oxidase +

catalase +

Question 12

What diseases can neisseria meningitidis cause?

Answer 12

Pharyngitis
Pneumonia
Meningitis

Question 13

Describe the pathogenesis of neisseria meningitidis

Answer 13

type IV pili allow it to bind to the cells of nasopharynx. It’s polysaccharide capsule prevents it from being destroyed by either lysosomes or PMNs. It releases endotoxins and lipooligosaccharides as toxins.

Question 14

Which four serotypes are included in the neisseria meningitidis vaccine?

Answer 14

A, C, Y, W135

Question 15

From a throat culture, you find a gram positive cocci. It is catalase negative and beta-hemolytic. What bacteria is this?

Answer 15

streptococcus pyogenes

Question 16

What diseases can streptococcus pyogenes cause?

Answer 16

scarlet fever

pharyngitis

Question 17

Describe the pathogenesis of streptococcus pyogenes.

Answer 17

Capsule protects it from phagocytosis and complement.

Lipotechoic acid and T proteins mediate adhesion to the respiratory cells.

M proteins binds complement and immunoglobulins

Various DNAse, streptolysins, and peptidases chew up complement, blood cells, and pepetides.

pyogenic endotoxins produce sickness.

Question 18

How is streptococcus pyogenes usually diagnosed?

Answer 18

Rapid antigen detection test; it is not usually cultured and tested.

Question 19

From a throat culture, you find a gram positive cocci. It is catalase positive. What bacteria is this?

Answer 19

staphylococcus aureus

Question 20

Describe the pathogenesis of staphylococcus aureus

Answer 20

Capsule protects it from phagocytosis

Expresses lipase, nuclease and hyaluronidase to chew up cells.

Lipotechoic acids and protein A promote cell binding

Coagulase activates fibrinogen into fibrin

various cytotoxins are released

Question 21

From a throat culture, you find a gram positive cocci. It is catalase negative and alpha-hemolytic. What bacteria is this?

Answer 21

streptococcus pneumoniae

Question 22

What diseases can streptococcus pneumoniae cause?

Answer 22

lobar pneumonia
sinusitis
otitis media

Question 23

Describe the pathogenesis of streptococcus pneumoniae

Answer 23

pneumolysin
capsule
adehsion proteins

Question 24

From a throat culture, you find a gram negative rod. It grows on chocolate agar. What bacteria is this?

Answer 24

Haemophilus influenzae

Question 25

What special nutrient requirements does haemophilus influenzae have?

Answer 25

requires heme and NAD

Question 26

What diseases can haemophilus influenzae cause?

Answer 26

pneumonia
sinusitis
epiglotitis
otitis

Question 27

Describe the pathogenesis of haemophilus influenzae

Answer 27

capsule protects from phagocytosis

Outer Membrane Proteins and Pili help bind to epithelial cells

LOS causes inflammation

Question 28

From a throat culture, you find a non-staining pleiomorphic cocci. It looks like a fried egg. What bacteria is this?

Answer 28

Mycoplasma pneumoniae

Question 29

What diseases are associated with mycoplasma pneumoniae?

Answer 29

tracheobronchitis

atypical pneumonia

Question 30

Describe the pathogenesis of mycoplasma pneumonia

Answer 30

Bacteria uses the P1 to attach next to the cilia, release toxins and destroy the cilia.

Question 31

From a throat culture, you find a gram negative rod. It is oxidase positive. What bacteria is this?

Answer 31

Pseudomonas aeruginosa

Question 32

What disease is pseudomonas aeruginosa infection associated with?

Answer 32

Cystic fibrosis, but could be any immunocompromised individual.

Question 33

Describe the pathogenesis of pseudomonas aeruginosa

Answer 33

Opportunistic infection
Forms a biofilm
Attaches to endothelial cells via adhesins and pilins
Releases various enzymes and endotoxins

Question 34

From a throat culture, you find a gram negative rod. It only grows on charcoal yeast extract. What bacteria is this?

Answer 34

Legionella pneumophilia

Question 35

What diseases can legionella pneumophilia cause?

Answer 35

Pontiac fever

Legionnaire’s Disease

Question 36

Describe the pathogenesis of pseudomonas aeruginosa

Answer 36

survives inside alveolar macrophages

produces endotoxins

Question 37

Describe the pathogenesis of mycobacterium tuberculosis

Answer 37

bacteria produce mycolic acids and liparabinomannan

PMNs over react causing necrosis