Bugs: Haemophilus, Legionella, Bordetella

Question 1

Haemophilis:

• what are the important species to know ?
• bacteriology:
  gram? shape? aerotolerance?
  whats unique about its plating?

Answer 1

H. Influenza
H. Ducreyi

Gram Negative
Cocco-bacilli
facultative anearobe
Encapsulated (6) vs unecapsulated

Plate: Chocolate Agar
Blood factors on plate: Hemin and NAD

Question 2

What is the most predominant encapsulated strain?

Answer 2

HiB (Type B) – most virulent

Question 3

Describe the pathogenic sequence of H Flu?

• how is it acquired ?
• what happens to encapsulated vs unencapsulated strains?

Answer 3

Acquired through Aerosoles

Unencapsulated strains: local disesae of the resp tract (otits media, sinusitis, PNA, bronchitis)

Encapsulated strains: can escape to the blood stream and become systemic disease such as: meningitis, conjunctivitis; cellulitis of the face; epiglotitis; arthritis; bacteremia

most commonly associated with COPD exacerbations

Question 4

Virulence Factors of H Flu.

- what is an important “acid” ?

Answer 4

• polysaccharide PRP Capsule – (HiB)
• Adhesion factors: pilus

LOS - Lipo oligo saccharide (adherence; terminal Sialic Acid prevents complement activation)

Biofilm Formation – LOS sialylation;

Question 5

Treatment and Prevention of H. Flu

• unencapsulated Strains
• Encapsulated strains
• immunization

Answer 5

unencapsulated Strains – Amoxicillin, Amox/Clav

• Encapsulated strains – 3rd Gen Cephalosporins
• immunization – PRP protein conjugate

Question 6

Moraxella catarrhalis:
Bacteriology
Manifestations of disesase

Answer 6

Gram Negative cocco-bacilli

Otitis Media, Sinusitis, conjuctivitis

Question 7

Treatment of Moraxella Catarrhalis

Answer 7

Amoxicillin / clavulanate

cephalosporins

Question 8

Legionella Pneumophila:
- Epi
how is it spread
where does it live

Answer 8

§ Spreads via aerosols
§ Present in natural waters – hot tubs, water tanks, air conditioners,
nosocomial
can also live in ameobas

Question 9

Legionella –
Staining
Morphology

Answer 9

• Stains poorly with gram stains
• Need to use Gimenez, Dieterle Stains
• Media: long, thin bacilli
• Tissues: short cocco bacilli

Question 10

What diseases are caused by Legionella?

Answer 10

Legionairre’s Disease: – severe PNA, fever, non productive cough, chills, HA
Treat with Abx

Pontiac Fever: Flu like; no PNA;
self limited
no need for Abx

Question 11

Pathogenesis and Virulence of Legionella?

• where do they attach ?

Answer 11

Attachment and entry into Alveolar Macrophages
by bindng complement components
divide within macrophages

Type IV secretions: Dot/ICM – inhibit early phagosome acidification and phagolysosome fusion

Multiplication within the vacuole
Depletion of amino acids – bacteria become more virulent
Vacuole lysis and spread to new cells

Question 12

Diagnosis of Legionella

• what stains can be used on culture?
• what other tests are there?

Answer 12

Stains:
Gimenez, Dieterle

Urine Antigen Test – dectects LPS of serotype 1

Fluoroescent Ab from sputum

Question 13

Treatment of Legionella

Prevention

Answer 13

§ Beta lactam abx are INEFFECTIVE
§ PNA Empiric Treatment:
□ FQ – Levofloxacin (quinone)
□ Macrolides: If confirmed as Legionella – azithromycin

Prevention- – source control

Question 14

Coxiella burnettii -

• what is it closely related to?
• what are the risk factors
• bacteriology:

Answer 14

○ Similar to and closely related to legionella

	○ Morphology: Gram negative, obligate intracellular bacillus 

		§ Risk Factors: Persons exposed to domestic live stock

Question 15

Coxiella Burnetti
- what disease does it cause ?

How is it treated?

Answer 15

Q Fever – self limiting, but can cause endocarditis in chronic form

Treatment: Doxycyclin

Question 16

Corynebacterium diphtheriae

bacteriology:

Answer 16

§ Gram positive rod
§ Aerobic
§ Non spore forming

Question 17

Corynebacterium diphtheriae
:Disease
Virulence factors

Answer 17

Diphtheria: acute respiratory infection with pseudmembrane formation in the throat

		§ Diphtheria Toxin -- 
			□ ADP ribosylation of EF2-----> Inhibition of protein synthesis

Question 18

Corynebacterium diphtheriae

Treatment & Prevention

Answer 18

Treatment: Anti-toxin (anti-serum) + Erythromycin, or PCN

Vaccination: DPT vaccine

Question 19

Bordetella (Pertussis)

• name the human pathogenic species
• bacteriology

what medium are they grown on?

Answer 19

B. Pertussis — whooping cough
B. parapertussin – milder disease

Gram negative
Cocco-bacilli
No capsule

Borden Gengou / Regan Lowe Mediums

Question 20

Describe the clinical presentation of Whooping Cough

Answer 20

• Catarrhal Stage (1-2 weeks)– highly contagious;
  fever, malaise, rhinorrhea, anorexia
• Paraoxysmal Stage (weeks 2-5)– Severe paroxysmal cough, Inspiratory whoops, vomiting, apnea
• Covalesncent Stage - cough can persist for weeks/months after bacteria are absent
• Critical pertussis in infants: Apnea, PNA, seizures, pulmonary HTN, lymphocytes, can lead to respiratory failure and death

Question 21

Virulence of Bordetella Pertussis

Answer 21

Adherence to Ciliated respiratory epithelium

• Pertussis Toxin (ADP Ribosylating Toxin of G proteins which inhibit innate immune response) + Lymphocytosis

Adenylate Cyclase Toxin – inactivates neutrophils

Question 22

Treatment of Pertussis:

Prevention of pertussis

Answer 22

Azithromycin – will stop growth of bacteria if the bacteria are still present

• no effect of cough suppresant
• should also provide supportive care (hydration, ventilation)

Vaccines: Dtap, Tdap