Bugs: Haemophilus, Legionella, Bordetella Flashcards
Haemophilis:
- what are the important species to know ?
- bacteriology:
gram? shape? aerotolerance?
whats unique about its plating?
H. Influenza
H. Ducreyi
Gram Negative
Cocco-bacilli
facultative anearobe
Encapsulated (6) vs unecapsulated
Plate: Chocolate Agar
Blood factors on plate: Hemin and NAD
What is the most predominant encapsulated strain?
HiB (Type B) – most virulent
Describe the pathogenic sequence of H Flu?
- how is it acquired ?
- what happens to encapsulated vs unencapsulated strains?
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
Virulence Factors of H Flu.
- what is an important “acid” ?
- polysaccharide PRP Capsule – (HiB)
- Adhesion factors: pilus
LOS - Lipo oligo saccharide (adherence; terminal Sialic Acid prevents complement activation)
Biofilm Formation – LOS sialylation;
Treatment and Prevention of H. Flu
- unencapsulated Strains
- Encapsulated strains
- immunization
unencapsulated Strains – Amoxicillin, Amox/Clav
- Encapsulated strains – 3rd Gen Cephalosporins
- immunization – PRP protein conjugate
Moraxella catarrhalis:
Bacteriology
Manifestations of disesase
Gram Negative cocco-bacilli
Otitis Media, Sinusitis, conjuctivitis
Treatment of Moraxella Catarrhalis
Amoxicillin / clavulanate
cephalosporins
Legionella Pneumophila:
- Epi
how is it spread
where does it live
§ Spreads via aerosols
§ Present in natural waters – hot tubs, water tanks, air conditioners,
nosocomial
can also live in ameobas
Legionella –
Staining
Morphology
- Stains poorly with gram stains
- Need to use Gimenez, Dieterle Stains
- Media: long, thin bacilli
- Tissues: short cocco bacilli
What diseases are caused by Legionella?
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
Pathogenesis and Virulence of Legionella?
- where do they attach ?
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
Diagnosis of Legionella
- what stains can be used on culture?
- what other tests are there?
Stains:
Gimenez, Dieterle
Urine Antigen Test – dectects LPS of serotype 1
Fluoroescent Ab from sputum
Treatment of Legionella
Prevention
§ Beta lactam abx are INEFFECTIVE
§ PNA Empiric Treatment:
□ FQ – Levofloxacin (quinone)
□ Macrolides: If confirmed as Legionella – azithromycin
Prevention- – source control
Coxiella burnettii -
- what is it closely related to?
- what are the risk factors
- bacteriology:
○ Similar to and closely related to legionella
○ Morphology: Gram negative, obligate intracellular bacillus § Risk Factors: Persons exposed to domestic live stock
Coxiella Burnetti
- what disease does it cause ?
How is it treated?
Q Fever – self limiting, but can cause endocarditis in chronic form
Treatment: Doxycyclin
Corynebacterium diphtheriae
bacteriology:
§ Gram positive rod
§ Aerobic
§ Non spore forming
Corynebacterium diphtheriae
:Disease
Virulence factors
Diphtheria: acute respiratory infection with pseudmembrane formation in the throat
§ Diphtheria Toxin -- □ ADP ribosylation of EF2-----> Inhibition of protein synthesis
Corynebacterium diphtheriae
Treatment & Prevention
Treatment: Anti-toxin (anti-serum) + Erythromycin, or PCN
Vaccination: DPT vaccine
Bordetella (Pertussis)
- name the human pathogenic species
- bacteriology
what medium are they grown on?
B. Pertussis — whooping cough
B. parapertussin – milder disease
Gram negative
Cocco-bacilli
No capsule
Borden Gengou / Regan Lowe Mediums
Describe the clinical presentation of Whooping Cough
- 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
Virulence of Bordetella Pertussis
Adherence to Ciliated respiratory epithelium
- Pertussis Toxin (ADP Ribosylating Toxin of G proteins which inhibit innate immune response) + Lymphocytosis
Adenylate Cyclase Toxin – inactivates neutrophils
Treatment of Pertussis:
Prevention of pertussis
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
