Haemophillus, Legionella, Bordetella, Chlamydia, Mycoplasma

Question 1

What is the morphology of Haemophilus?

Answer 1

Gram negative coccobacilli

Question 2

Can you grow Haemophilus on blood agar?

Answer 2

No, requires blood factors hemin (X factor) and NAD (V factor) that are released from blood cells by heating.
Need chocolate agar.

Question 3

What types of diseases does encapsulated v. unencapsulated H. influenze cause?

Answer 3

Unencapsulated: local respiratory infections
Encapsulated: systemic disease (in blood stream)

Question 4

Which encapsulated H. influenzae type is predominant in invasive disease?

Answer 4

Type b (Hib)

Question 5

What is the treatment of choice for non-invasive unencapsulated strain H. influenzae infections?

Answer 5

Amoxicillin

Amox-clavulanate for resistant strains

Question 6

What is the treatment of choice for invasive encapsulated Hib (Type B H. influenzae) infections?

Answer 6

3rd generation cephalosporin

Question 7

What made the Hib vaccines more successful?

Answer 7

Conjugate! Hib capsule polysaccharide conjugated to protein carrier

Question 8

What diseases are caused by Moraxella?

Answer 8

Otitis (one of three major bacterial causes)
Sinusitis
Conjunctivitis

Question 9

What is the treatment for Moraxella?

Answer 9

Amoxicillin/clavulanate

Question 10

How is Legionella primarily spread?

Answer 10

Aerosols from water systems (NOT person to person)

Question 11

What differentiates Legionnaire’s disease from other pneumonias?

Answer 11

Very severe, can spread to brain, high mortality but low attack rate

Question 12

What is the pathogenesis of Legionella?

Answer 12

Multiplies in alveolar macrophages
Forms vacuoles
Dot/Icm type IV secretion system exports vacuole contents into cell

Question 13

What stains are used for Legionella?

Answer 13

Gimenez and Dieterle

Question 14

What is the treatment for Legionella?

Answer 14

Azithromycin (or fluoroquinolone)

Question 15

What population is at risk for Coxiella infection (Q fever)?

Answer 15

People that interact with animals (farmers, ranchers, vets)

Question 16

What is the treatment for Coxiella?

Answer 16

Doxycycline

Question 17

What disease does Corynebacterium diphtheriae cause?

Answer 17

Diptheria (acute respiratory infection)

Don’t have in US because of DTP vaccine

Question 18

What disease does Bordetella pertussis cause?

Answer 18

Pertussis (whooping cough)

Question 19

How is pertussis spread?

Answer 19

Aerosols, from adults as a reservoir to young children

Question 20

What are the stages of pertussis?

Answer 20

Catarrhal (cold-like symptoms)
Paroxysmal (severe cough paroxysms, apnea)
Convalescent stage (cough may persist, bacteria absent)

Question 21

What is the treatment of B. pertussis?

Answer 21

Azithromycin (to prevent further spread but no benefit to patient)
Supportive therapy

Question 22

How does pertussis toxin (PTX) exert its effect?

Answer 22

ADP-ribosyl transferase that modifies target G proteins

Inhibits the innate immune response

Question 23

What is the morphology of Legionella?

Answer 23

Gram negative, pleomorphic (long bacilli in media, short coccobacilli in tissue)

Question 24

What is the morphology of Bordetella?

Answer 24

Gram negative coccobacilli

Question 25

What is the morphology of Corynebacterium diptheriae?

Answer 25

Gram positive rod

Question 26

What is the morphology of chalmydia?

Answer 26

Gram negative coccobacilli

Question 27

What are the two species of Chlamydia infections that usually affect humans?

Answer 27

C. trachomatis | C. pneumoniae

Question 28

What are the two forms of Chlamydia during its developmental cycle?

Answer 28

EB (elementary body, spore-like form) | RB (reticulate body, metabolically active and multiplies intracellularly by binary fission)

Question 29

Describe developmental cycle of Chlamydia

Answer 29

- EB (spore-like form, metabolically inactive, dense) is internalized into cell in inclusion membrane - EB differentiates into RB almost immediately (larger, less dense, metabolically active) - RB multiplies intraceullularly within the inclusion membrane - RBs condense back into EBs - Inclusion exocytosed/cell lysed and progeny EBs go on to infect other cells

Question 30

What is the main way Chlamydia releases its virulence effector proteins?

Answer 30

Type III secretion system (like molecular syringe that injects virulence factors into infected cell)

Question 31

What diseases are caused by Chlamydia trachomatis?

Answer 31

``` Trachoma (Serovars A, B, C) Inclusion conjunctivitis Neonatal pneumonitis (from mother at birth) STI (Serovars D-K) ```

Question 32

What sequelae is most commonly linked with Chlamydia pneumoniae?

Answer 32

Atherosclerotic plaques in CVD

Question 33

What is the treatment of choice for Chlamydia pneumoniae?

Answer 33

Doxycycline or erythromycin

Question 34

Who is at risk for Chlamydia psittaci?

Answer 34

People that interact with bird feces (pet-store, poultry farm, power line workers)

Question 35

What is the morphology of Mycoplasma?

Answer 35

Wall-less pleiomorphic bacteria Fried egg colony morphology (except M. pneumoniae - mulberry colonies)

Question 36

What exhibits cold agglutinins?

Answer 36

M. pneumoniae

Question 37

What disease are M. hominis, M. genitalium and Ureaplasma urealyticum associated with?

Answer 37

STI

Question 38

What disease are M. fermentans or M. penetrans associated with?

Answer 38

HIV

Question 39

What toxin does M. pneumoniae produce?

Answer 39

Community Acquired Respiratory Distress Syndrome (CARDS) toxin - an ADP-ribosylating and vacuolating toxin