HRR: gram negative rods

Question 1

What are the three species of Bordetella that infect humans?

Answer 1

1. Pertussis: causes whooping cough
2. Parapertussis: milder pertussis-like illness
3. Bronchiseptica: kennel cough in canines and sometimes chronic respiratory tract infection in humans

Question 2

What are some clinical manifestations of Bordetella pertussis?

Answer 2

Black eyes, whooping cough, dehydration, exhaustion

Question 3

Describe culture of Bordetella pertussis.

Answer 3

It requires a special medium and grows slow; antibiotics are needed. It is too late to culture once the cough starts as the bacteria is usually cleared.

Question 4

Describe the 3 stages of Bordetella pertussis.

Answer 4

1. Catarrhal: 1-2 weeks and causes fever, malaise, profuse rhinorrhea
2. Paroxysmal: 2-4 weeks and causes coughing, lymphocytosis, and whoop (audible gasps for breath)
3. Convalescent: symptoms fade

Question 5

Describe clinical presentation of Bordetella.

Answer 5

Bacteremia does not occur. Infants have a high mortality rate. Adult disease is atypical. Bacterial replication is localized to respiratory epithelium. Can cause rib fracture.

Question 6

What are the virulence factors of B. pertussis?

Answer 6

Adhesins (pili and FHA) and exotoxins (pertussis toxin, AC, and TCT)

Question 7

Describe the pathogenesis of B. pertussis.

Answer 7

1. It adheres to cilia via FHA
2. PT and pore-forming AC injure cells
3. TCT damages ciliated epithelium
4. PT absorbed into bloodstream and causes immune dysregulation

Question 8

Describe PT toxin.

Answer 8

An AB toxin that ADP-ribosylates G proteins that regulate adenylate cyclase; the effect is tissue specific.

Question 9

What are systemic effects of PT and AC?

Answer 9

Lymphocytosis, inactivation of neutrophils/macrophages/lymphocytes, histamine sensitization, insulin secretion

Question 10

How do we prevent B. pertussis?

Answer 10

Acellular pertussis vaccines DTaP and Tdap booster

Question 11

What can be found in Tdap boosters?

Answer 11

Inactivated PT, FHA, and other virulence factors

Question 12

What are the two human pathogens of Haemophilus?

Answer 12

H. influenza and H. ducreyi

Question 13

What do the Haemophilus require for growth?

Answer 13

H. influenza requires hematin and NAD, while H. ducreyi only needs hematin. Blood must be lysed for them to get these.

Question 14

How is H. influenza typed?

Answer 14

If they are encapsulated, they are typed by antibodies specific for the capsular material.

Question 15

What is the worst strain of H. influenzae? What is the capsule made of?

Answer 15

Type B; polyribitol phosphate

Question 16

What are some common characteristics of encapsulated and non-encapsulated H. influenzae that help cause disease?

Answer 16

Adhesins (pili and outer membrane proteins) and endotoxins (LOS and LPS)

Question 17

What are the virulence factors of Haemophilus?

Answer 17

Attachment via pili and HMWs and anti-phagocytic capsules if they are encapsulated. This allows them to enter the bloodstream.

Question 18

What are clinical manifestations of encapsulated H. influenza?

Answer 18

Cellulitis, purulent meningitis, acute epiglottis, pneumonia and septic arthritis, bacteremia

Question 19

What are clinical manifestations of non-encapsulated H. influenza?

Answer 19

Chronic sinusitis, otitis media, chronic bronchitis, pneumonia

Question 20

How does H. influenzae spread?

Answer 20

Through respiratory droplets; only spread person to person.

Question 21

Describe immunity to H. influenzae.

Answer 21

At 0-6 months you’re protected by maternal antibodies. 6-18 months there is a lack of T-independent immune response. Over 18 months there is increasing immunity.

Question 22

What confers protection against H. influenzae?

Answer 22

Anti-PRP antibodies

Question 23

How do we diagnose H. influenzae?

Answer 23

Clinical presentation, gram stain, growth on chocolate agar.

Question 24

How do we treat H. influenzae?

Answer 24

Empiric therapy, beta lactams with beta lactamase inhibition, rifampin prophylaxis.

Question 25

Describe H. ducreyi.

Answer 25

It is an STI that causes soft and painful ulcers. You can be infected over and over again, and the ulcers increase HIV transmission.

Question 26

Describe the growth of Pseudomonas.

Answer 26

Very minimal growth requirements; can grow in wide temperature range, is salt tolerant, grows readily on common media, and is hemolytic on blood agar.

Question 27

Describe Pseudomonas.

Answer 27

Motile, pale-staining, aerobic gram-negative rod.

Question 28

What is the relation between Pseudomonas and lactose?

Answer 28

It fails to ferment it.

Question 29

What are distinctive features of Pseudomonas aeruginosa?

Answer 29

Colorful water-soluble pigment, strong odor, oxidase positive, and mucoid colonies.

Question 30

What are infection sites for Pseudomonas?

Answer 30

Eyes, ears, burns, wounds, catheters (UTI), and in cystic fibrosis.

Question 31

What are the virulence factors of Pseudomonas aeruginosa?

Answer 31

1. LPS
2. Pili
3. Flagella
4. Slime made of secretion of alginate polymer
5. Exotoxin A that inactivates EF2
6. Elastase that cleaves elastin, IgA/G, and complement components
7. Exotoxin S that acts on protein G to affect the cytoskeleton and induce apoptosis.

Question 32

What injection system does exotoxin S use?

Answer 32

Type III.

Question 33

What does elastase do?

Answer 33

Disrupts blood vessels and lung structures.

Question 34

Which species survives in tap water?

Answer 34

Pseudomonas aeruginosa.

Question 35

What are modes of transmission of Pseudomonas aeruginosa?

Answer 35

Sinks, nebulizers, humidifiers, contact lens solution, pools.

Question 36

What is the most significant pathogen in cystic fibrosis patients?

Answer 36

Pseudomonas aeruginosa.

Question 37

What are clinical presentations of Pseudomonas aeruginosa?

Answer 37

Infections of burns and wounds, pneumonia with necrosis/infarct/vascular invasion, otitis externa, folliculitis, eye infection.

Question 38

What temperature does Pseudomonas grow at?

Answer 38

42 Celsius.

Question 39

How do we diagnose Pseudomonas?

Answer 39

Growth at 42 degrees on almost any media showing pigment production and positive oxidase.

Question 40

How do we treat Pseudomonas aeruginosa?

Answer 40

It is pretty resistant to antibiotics, and the only effective agents are given IV. CF patients can be given cipro and aztreonam.

Question 41

Which gram-negative species do not ferment lactose?

Answer 41

Pseudomonas and Burkholderia.

Question 42

What are the virulence factors of Burkholderia?

Answer 42

Elastase, adhesins, and LPS.

Question 43

Describe Burkholderia cepacia.

Answer 43

An opportunistic pathogen found in aquatic environments that colonizes in CF patients and causes rapidly fatal cepacia syndrome with respiratory distress and septicemia.

Question 44

How is Burkholderia cepacia transmitted?

Answer 44

Contaminated IV solutions, nebulizers, disinfectant, urinary catheters.

Question 45

How do we treat Burkholderia?

Answer 45

It is resistant to many antibiotics, so TMP-SMX is first line.

Question 46

Where do we find Burkholderia pseudomallei?

Answer 46

Southeast Asia and aquatic environments.

Question 47

How is Burkholderia transmitted?

Answer 47

Inhaled, ingested, traumatic inoculation.

Question 48

What is the clinical presentation of Burkholderia pseudomallei?

Answer 48

Melliodosis, acute pneumonia, cutaneous melliodosis.

Question 49

What population might we see Burkholderia pseudomallei in?

Answer 49

Vietnam veterans.

Question 50

Describe Burkholderia mallei.

Answer 50

Causes glanders in horses and sometimes humans; presents with ulcerative lesions in nasal mucosa and lung nodules.