Bugs - Haemophilus, Legionella, Bordetella

Question 1

clinically relevant haemophilus species

Answer 1

**H. influenzae **(most important)

**H. ducreyi **(chancroid, genital ulcers)

Question 2

morphology of haemophilus

Answer 2

small, GN, coccobaccilli

Question 3

required factors for culturing haemophilus?

Answer 3

need X factor(hemin) and V factor(NAD)

requires chocolate agar: heated blood agar which causes the release of these factors

Question 4

H. influenzae virulence factors

Answer 4

• polysacchardie capsule(if encapsulated obviously)
• adherence factors
  
  • pili
  • HMW adhesins(unencapsulateD)
• lipooligosaccharide(LOS)- can be modified by sialic acid terminal addition
• biofilm formation(LOS sialylation)

Question 5

treatment for H. influenzae

Answer 5

unencapsulated/non-invasive - amoxicillin; amoxicillin-clavulanate for resistant strands

Hib(meningitis) - cefotaxamine(3rd gen cephalo)

Question 6

most clinically relavent moraxella species

Answer 6

m. catarrhalis

Question 7

types of moraxella infections and treatment

Answer 7

otitis media, sinusitis, conjuctivitis(rarely systemic) treat with amoxicilin/clavulanate use cephalosporins for more serious

Question 8

h. influenzae diseases(encapsulated and unencapsulated)

Answer 8

Hib - meningitis, conjuctivitis, cellulitis, epiglottitis, bacteremia, arthritis (ABCCME)

unencapsulated - otitis media, sinusitis, bronchitis, pneumonia (BOPS)

Question 9

treatment for h. influenzae

Answer 9

amoxicillin for non-invasive(unencapsulated); amoxicillin-clavulanate for resistant strands

3rd gen cephalosporin(cefotaxamine) for invasive Hib(meningitis)

Question 10

describe the h. influenzae vaccine

Answer 10

PRP(polyribosyl ribitol phosphate) attached to protein conjugate

Question 11

treatment for moraxella infections

Answer 11

treat m. catarrhalis with amoxicillin/clavulanate, cephalosporins

just like haemophilus

Question 12

clinically relevant legionella spp.

Answer 12

L. pneumophilia

Question 13

how are legionella infections spread?

Answer 13

aerosolized water sources:

• showers
• whirlpools
• humidifiers
• tap water/faucets
• cooling towers

Question 14

who is at higher risk for legionella infections?

Answer 14

elderly/immunocompromised

smoking, chronic lung disease, TLR5(flagellum) polymorphism

Question 15

pathogenesis for L. pneumophilia

Answer 15

1. attach/entry into alveolar macrophages(bind C’, type IV pili)
2. inhibit fusion of phagolysosome
3. begins replicating in vacuole
4. secretes virulence factors via Dot/Icm type IV secretion system
5. keeps growing till cell lyses then moves to next cell

Question 16

diseases caused by legionella

Answer 16

1. Legionnaires Disease - severe pneumonia
   
   • fever, nonproductive cough, chills, HA
   • cerebellar involvement often
   • 15-20% moretality
   • need antibiotics
2. Pontiac Fever - flu like symptoms(mild)
   
   • high attack rate, but <1% mortality
   • no person-person spread
   • no therapy needed

Question 17

diagnostics for legionella

Answer 17

hard to gram stain

• use Giminez(smears) or Dieterle(tissue) stains
• urine antigen test(detects LPS serogroup 1)
• direct fluorescent a-body test from sputum

Question 18

treatment for legionella

Answer 18

fluoroquinolones(levofloxacin) for CA-pneumonia

• change to azithromycin if legionella is diagnosed

Question 19

coxiella

relavent species?

epidemiology?

Answer 19

C. burnetii is most relavent species

found in animal reservoirs; commonly seen in farmers, ranchers, vets

Question 20

coxiella

diseases?

treatment?

Answer 20

Q fever(self-limiting flu-like illness) –> chronic form includes endocarditis

Treat with doxycycline

Question 21

corynebacterium

relavent species?

morphology?

disease, toxins?

treatment?

Answer 21

corynebacterium diphtheriae

aerobic GP rod

Diptheria: acute resp. infection w/pseudomembrane formation in throat

• resp. failure, myocarditis, neuritis, death
• uncommon in US
• mediated by diptheria toxin - inhibits protein synthesis

Treatment: antitoxin serum plus erythromycin or penicillin

Question 22

relavent bordetella species

Answer 22

**b. pertussis **(whoopin cough)

**b. parapertussis **(milder disease)

Question 23

GN coccobacilli

no capsule

small

causes whooping cough

Answer 23

bordatella

b. pertussis specifically

Question 24

bordatella toxins/virulence factors

Answer 24

1. pertussis toxin (PTX):

• ADP-ribosyl transferase(Gi protein target)
• causes lymphocytosis(systemic disease); bad prognosis
• immunosuppressive when infecting, then causes inflamm later…bad

_ other toxins:_

a) adenylate cyclase toxin – targets and inactivates neutrophils
b) tracheal cytotoxin and **lipopolysaccharide - **combine to destroy cilia on epthelial cells

Question 25

bordatella treatment

Answer 25

1. azithromycin or clarithromycin to prevent spread(doesnt stop symptoms)
2. supportive therapy - hydration, nutrition, oxygen

Question 26

epidemiology of bordatella

Answer 26

• HIGHLY contagious; spread via aerosols
• majority of cases in young children, most deaths <1 y/os
• adults have less severe symptoms but are likely reservoirs

Question 27

diagnosis of bordatella

Answer 27

culture on bordet-gengou or regan-lowe mediums

PCR, serology

Question 28

stages of bordatella disease

Answer 28

• *1. catarrhal stage** - cold-like symptoms, highly infectious, 2 weeks
• *2. paroxysmal stage** - severe cough paroxysms, apnea, may cause hypoxia, striking leukocytosis

**3. ** convalescent stage - cough may persist for several months, bacteria absent

**4. ** critical pertussis in infants

   - **lymphocytosis**, apnea, can progress to respiratory failure and death

Question 29

morphology of coxiella

Answer 29

GN, intracellular bacillus

related to legionella